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CXC Study Guide - Biology Unit 1 for CAPE

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Biology
for
CAPE®
Unit
1
Biology
for
CAPE®
Richard
Stuart
Lorna
Fosbery
LaPlace
McPherson
Unit
1
3
Great
Clarendon
Oxford
It
University
furthers
and
Oxford
The
©
This
in
means,
Press,
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the
the
the
part
prior
of
have
of
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in
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by
law,
reproduction
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mark
of
countries
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2012
2015
2012
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of
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the
2015
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Oxford
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Acknowledgements
Cover
photograph:
Illustrations:
Page
The
make-up:
authors
Mark
Wearset
and
Wearset
the
Lyndersay,
Ltd,
Boldon,
Ltd,
Boldon,
publisher
Lyndersay
Tyne
would
&
Tyne
like
Digital,
Trinidad.
www.lyndersaydigital.com
Wear
&
to
Wear
thank
the
following
for
permission
to
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material:
Photos
Module
Luttick
Biology
2.5.1
1:
1.8.3
( James
on
DR
Module
DVD,
2:
SCIENCE
2.2.1
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4.4.1
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Fig.
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2009;
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PHOTO
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Bruce
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Springer-Verlag
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PHOTO
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LIBRARY;
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2009;
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every
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Springer-Verlag
holders
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AND
Gunning,
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LIBRARY;
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PHOTO
Getty;
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PHOTO
LIBRARY;
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Girls’
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KEITH
SCIENCE
STEVE
Allen’s
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all
at
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resource
for
teachers,
by
B
Contents
Introduction
v
3.4
Determining the
initial
rate of
reaction
Module
1
Cell
and
3.5
molecular
biology
2
Introduction to
biochemistry
1.2
Water
1.3
Carbohydrates
1.4
Complex
1.5
Lipids
1.6
Proteins
(1)
12
1.7
Proteins
(2)
14
1.8
Proteins
(3)
16
1.9
Qualitative
1.
10
Quantitative
Factors
hydrogen
bonding
sugars
(1)
56
inuencing
enzyme
(2)
58
4
3.7
–
enzyme
2
activity
and
inuencing
activity
3.6
1.
1
Factors
54
Practice
exam-style questions:
6
Enzymes
carbohydrates
10
biochemical tests
1.
11
1.
12
18
biochemical
tests
Module
natural
2
Genetics, variation
and
selection
62
1.
1
Nucleic
acids
62
1.2
DNA
1.3
Protein
synthesis
(1)
66
1.4
Protein
synthesis
(2)
68
1.5
Protein
synthesis
(3)
70
1.6
Genes to
1.7
Practice
replication
64
20
Biochemistry
Practice
summary
22
phenotypes
72
exam-style questions:
Biochemistry
exam-style questions:
24
Structure
2.
1
Introduction to
cells
26
2.2
Cells
–
microscopy
28
2.3
Cells
and organelles
2.4
Eukaryotes
2.5
Tissues
2.6
Cell
2.7
Movement
2.8
Investigating
2.9
Cell
2.
10
Practice
Cell
60
8
electron
and
30
prokaryotes
and organs
34
membranes
across
32
36
membranes
water
potential
summary
38
40
structure
and function
3.
1
Enzymes
3.2
Investigating
enzyme
3.3
Quantitative
results
46
48
activity
50
roles of
nucleic
acids
74
2.
1
Mitosis
(1)
76
2.2
Mitosis
(2)
78
2.3
Life
2.4
Meiosis
2.5
Segregation
2.6
Nuclear division
2.7
Practice
cycles
Mitosis
44
exam-style questions:
and
80
82
and
crossing over
84
summary
86
exam-style questions:
and
meiosis
3.
1
Introduction to
3.2
Terminology
3.3
Monohybrid
3.4
Codominance
in
88
genetics
genetics
cross
and
90
92
94
sex
linkage
96
52
iii
Contents
3.5
Dihybrid
3.6
Interactions
and
cross
98
between
Module
3
Reproductive
1.
1
Asexual
reproduction
1.2
Asexual
reproduction
3.8
Patterns of
in
104
owering
plants
146
inheritance
1.3
summary
Sexual
reproduction
in
108
owering
plants
148
exam-style questions:
Patterns of
4.
1
144
102
Chi-squared test
Practice
inheritance
Principles of
1.4
Pollination
150
1.5
Pollination to
1.6
Plant
1.7
Practice
110
seed formation
152
genetic
engineering
112
4.2
Gene therapy
114
4.3
Insulin
116
4.4
Genetically
4.5
Practice
Plant
production
modied organisms
reproduction
summary
154
exam-style questions:
reproduction
2.
1
Female
reproductive
2.2
Male
2.3
Gametogenesis
2.4
Fertilisation
156
system
158
118
reproductive
system
160
exam-style questions:
Aspects of
genetic
engineering
162
122
5.
1
Variation
(1)
124
5.2
Variation
(2)
126
5.3
Mutation
5.4
Sickle
5.5
Darwin
and
early
development
164
2.5
Internal development
166
2.6
Hormonal
128
cell
anaemia
control of
130
reproduction
168
132
2.7
5.6
144
alleles
genes
3.7
3.9
biology
Natural
selection
(1)
The
effect of
maternal
134
behaviour on foetal
5.7
Natural
selection
5.8
Species
5.9
Variation
and
(2)
how they
and
natural
136
evolve
selection
summary
5.
10
Practice
140
2.8
Human
2.9
Practice
Human
reproduction
172
summary
174
exam-style questions:
reproduction
176
exam-style questions:
Variation
iv
138
development
and
natural
selection
142
Glossary
178
Index
185
Introduction
This
Study
Guide
has
been
developed
exclusively
with
the
Caribbean
®
Examinations
candidates,
Council
both
in
)
(CXC
and
out
of
to
be
used
school,
as
an
additional
following
the
resource
Caribbean
by
Advanced
®
Prociency
Examination
It
prepared
)
(CAPE
programme.
®
has
been
teaching
and
by
a
team
examination.
with
The
expertise
contents
are
in
the
CAPE
designed
to
syllabus,
support
learning
®
by
providing
the
features
and
for
guidance
Inside
this
activities
On
of
in
to
problem
syllabus.
is
in
an
Do
provide
to
the
your
electronic
techniques:
candidate
answers
could
skill
syllabus
format!
examination-style
designed
questions
study
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answers
and
improved.
and
questions.
specically
inside
refer
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includes
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examination
sections
the
examination
example
where
examination
are
to
that
sample
Biology
CAPE
examination
with
show
your
in
master
and
CD
good
questions,
activities
to
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interactive
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requirements
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provide
syllabus
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We
your
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potential
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includes
lots
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hints,
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Biology.
CAPE
explanations
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suggestions
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of
each
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topic.
chapter
the
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start
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are
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summarising
concise
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give
these
There
you
book.
v
1
Cell
1.
1
Introduction
and
molecular
Just
completion
of
this
biochemistry
Chemistry of
Learning outcomes
On
to
section,
about

be
able
dene
of
everywhere
biochemistry
in
as
molecules
the
study
state
and
their
made
biological
of
elements: C,
conversion
is
the
the
basis
cell
of
state
that
walls
on
in
the
most
colour
plants.
of
Earth.
within
It
light
of
common
colour
chlorophyll,
is
used
energy
Chlorophyll
plant
surrounding
biological
the
in
your
main
cells.
those
to
to
is
inside
Cellulose
plant
absorb
cells.
light
chemical
is
and
energy
chloroplasts,
the
is
the
as
such
which
compound
Cellulose
is
and
that
are
forms
compound
on
most
Earth.
the following
H, O,
N,
S
and
Biochemistry
P
many
are
is
the
These
study
of
molecules
biological
are
the
molecules
building
and
blocks
their
of
life
roles
–
in
constantly
biological
polymers
made
assembled
monomer
and
taken
apart.
Metabolism
is
the
term
given
to
all
the
by
chemical
joining
the
molecules
being
molecules
life
found
organisms.

look
is
pigment
in
common
are
It
involved
organelles
organisms
that
you
green.
photosynthetic
the

is
to:
biological
roles
life
you
environment
should
biology
reactions
that
occur
in
organisms
and
can
be
divided
into:
molecules

together.
anabolism
from

catabolism
into
All
the
with
major
chlorophyll
is
carry
Y
ou
messages,
information,
The
air
and
compounds
know

and
of
The
you
is
of
use
life
are
in
–
are
known
we
Biology
–
pure
are
very
store
as
you
It
store
on
the
itself
and
also
by
form
biological
that
bres
that
provide
and
are
energy,
retrieve
functions.
dioxide,
nitrogen,
compounds.
compounds.
have
molecules
can
out
are
forms
carbon
progress
will
with
strong.
other
inorganic
organic
based
molecules
energy,
many
oxygen,
are
are
bonds
functions
biological
have
biological
reactions.
carried
cellulose
molecules
reactions
large
covalent
those
cannot
terms
down
functions
of
biological
organisms
and
of
These
so
of
that
composed
some
element
two
and
up
larger
anabolic
catabolic
bonds
reactions,
gases
and
your
just
as
form
range
learn
gases.
carbon
make
can
transducer
also
catalyse
Here
chemical
energy
will
that
up
as
break
known
covalent
bonds.
build
known
that
are
element
These
other
chemistry
chemistry.
they
transport
around
hydrogen
This
an
that
are
reactions
staggering
is
strong.
they
compounds
double
compounds
very
the
ones;
atoms.
and
reactions
ones;
carbon.
other
single
the
–
smaller
element
the
–
smaller
without
learnt
The
complex
Biochemistry
knowing
but
which
is
some
you
must
course:
chemical
substance
consisting
of
one
type
of
atom

atom
–
smallest
properties
and

protons,
isotope
–
neutrons
S tudy
compound

molecule
–
chemical
and
foc us
at
computer-generated
biological
molecules,
and
the
same
element
by
of
having
an
atom
the
chemical
consists
of
neutrons
electrons
element
with
different
numbers
of
nucleus
smallest
physical
made
from
particle
of
properties
a
of
two
or
more
substance
the
chemical
that
substance
retains
and
is
elements
the
composed
of
atoms
ion
–
an
or
atom
more
or
molecule
electrons
and
or
is
chemical
either
group
positively
that
or
has
lost
negatively
or
gained
charged
DNA.

2
surrounded
substance
the
more
of
an
nucleus
especially
one
proteins
or
a
is
of
the
models

of
the
–
element;
and
atoms
in
component
the

two
Look
of
ionic
bond
–
a
chemical
bond
between
two
ions
with
opposite
charges
Module

covalent
bond
electrons
–
a
chemical
between
atoms
bond
in
a
involving
the
sharing
of
a
pair
1
of
are
small
molecules
that
these
are
assembled
into
are
assembled
into
larger
ones.
In
small
much
larger
molecules.
Glucose
is
asked
The
molecule
small
that
is
assembled
molecules
are
in
known
different
as
ways
monomers,
to
the
polymers.
The
as
polymers.
Lipids
biological
summarised
are
Not
made
molecules
in
this
all
the
from
are
a
large
small
subdivided
biological
number
into
of
molecules
sub-unit
groups,
which
Elements
Sub-unit
carbohydrates
C,

H, O
(ratio
lipids
give
groups
of
molecules,
nucleic
acids.
students
See
page
often
62 for
larger
structure
and function
of
DNA
RNA.
are
molecules.
are
C,
molecules
Examples
glucose
starch

1 : 2 : 1)
Roles
(amylose
and
C,
H, O*
H, O,
glycerol, fatty

N,
acid
phosphate
S
amino

(20
acids
C,
H, O,
N,

energy
storage

glycogen

cellulose

support

triglycerides

energy

thermal

electrical

membranes
phospholipids

(phospholipids)
proteins
in organisms
amylopectin)

P
acids
different
types)
nucleotides

(ve
different
types)
storage
insulation
insulation

haemoglobin

transport

collagen

support

amylase

catalysts

pepsin

insulin

messengers

antibodies

protection

DNA

information
storage

RNA

information
retrieval

production
(mRNA,
*
the
table.
Macromolecules
nucleic
name
larger
and
molecules
to
a
the
molecules.
biology
some
forget
relatively
molecular
Link
biological
cases
and
molecule.
When
There
Cell
tRNA,
rRNA)
of
proteins
Note
Ratio
of
C : H
=
approx
1 : 2,
but
ratios
and
keep
of
C : O
and
H : O
are
high,
e.g.
9 : 1
and
18 : 1
Summary questions
Try
the
questions
1
Dene
below
the following

organic

macromolecule


your
answers
in
a folder
alongside
4
terms:
your
Name
notes.
one
biological
molecule
that
carries
out
each
of
the following functions:
compound

monomer
polymer.
energy
transduction

energy

information


storage
storage

transport
carrying
of
oxygen
messages
protection
against
disease-causing
2
List
3
Write
the four
main
groups
of
biological
molecules.
organisms
down
the
chemical formula for
glucose
and
5
show
how
to
calculate
its
relative
molecular
Explain
what
makes
carbon
suitable
as
the
‘element
mass.
life’.
3
of
1.2
Water
and
Learning outcomes
hydrogen
The
giver of
W
ater
On
completion
of
this
section,
forms
be
able
describe
approximately
humans,
and
70
per
makes
up
cent
of
about
the
90
bodies
per
cent
of
of
animals,
plants.
the
structure
of
a
water
molecule
and
all
Earth
by
water
organisms
water
are
O)
(H
and
many
organisms
dependent
should
be
a
on
gas
it.
like
At
live
the
in
it.
Life
evolved
temperatures
hydrogen
sulphide
we
(H
2

describe
hydrogen
between

list
the
water
liquid.
bonding
not
molecules
properties
of
There
water
explain
how
hydrogen
cells
the
bonding
properties
are
in
are
water
have
S)
on
and
not
a
2
reason
in
it
is
the
hydrogen
oxygen
atom
not
solar
probably
system
bonds
has
a
explains
(as
between
greater
far
as
water
attraction
why
we
life
on
Earth
and
know).
molecules.
for
exists
the
These
electrons
exist
in
the
because
covalent
is
bond
responsible for
The
elsewhere
the

All
to:
surrounded

life
you
including
should
bonding
with
hydrogen.
This
makes
the
oxygen
slightly
electronegative
and
of
the
hydrogen
slightly
electropositive
so
that
a
water
molecule
is
dipolar.
water
The

list
the
roles
of
water
in
partial
organisms
explain
as
an
the
importance
environment for
of
are
indicated
by
the
symbol
δ
(delta)
with
on
δ
the
+
oxygen

charges
living
water
organisms.
and
on
δ
slightly
negative
bond
very
is
easily
the
charge
weak
broken.
hydrogen.
In
and
(about
bodies
the
one
of
A
hydrogen
slightly
tenth
water
,
the
bond
positive
strength
hydrogen
forms
charge.
of
bonds
a
between
Each
covalent
break
and
the
hydrogen
bond)
reform
and
all
the
time.
W
ater
molecules
are
‘sticky ’
thanks
to
the
hydrogen
bonds
between
them.
a


This
cohesion
between
water
molecules
gives
water
important
properties


that
are
summarised
in
the
table
opposite.



S tudy
foc us

You
hydrogen

bond
the
may
roles
be
of
asked
water
to
in
discuss
living
how
the
organisms
structure
and
also
and
as
properties
an
of
water
environment.
explain
Remember

that
hydrogen
bonding
is
key
to
these
explanations.
b
Summary questions
Figure 1.2.1
1
Dene
2
Explain
3
Find
the
terms
why
solvent;
hydrogen
solute;
soluble;
bonds form
insoluble;
between
water
dipolar;
cohesion.
molecules.
a Two water molecules with
a hydrogen bond between them.
the
names
of
seven
different
biological
molecules
that
dissolve
in
b Each water molecule may have
water
and
seven
that
do
not.
hydrogen bonds with up to four other
water molecules.
4
Explain
the
medium
importance
and
a
of
water
as
a
component
of
cells,
a
transport
as
environment for
coolant.
Link
5
Hydrogen
cellulose;
bonds
this
are
will
important
be
dealt
in
9. They
are
also
with
important
(page
proteins
4
63)
(page
and
15).
in
advantages
and
disadvantages
of
water
an
on
Discuss
why
the
presence
of
liquid
water
on
Earth
is
so
in
we
DNA
the
organisms.
6
page
Discuss
know
it.
stabilising
7
Find
out
what
happened
to
water
on
the
planet Venus.
important for
life
as
Module
Property
Explanation
Roles of
water
1
in
Roles of
organisms
good
solvent for
substances
that
charged
dissolve
polar
molecules
(e.g.
glucose)
(e.g.
Na
solvent
and
in
water;
uncharged
within
also
dissolve,
and
are
)
are
less
readily
weak
solvent for
nutrients
(oxygen
and
and
carbon
transport
charged
attracted
to
dioxide)
e.g.
charges
on
blood
the
plasma;
but
an
−
, Cl
media,
substances
cells
gases
in
as
environment
ions
solvent
+
readily
water
lymph;
phloem
carbon
dioxide
is
much
water
and
xylem
saps
more
soluble
than
oxygen
molecules
high
specic
heat
capacity
4.2 J
are
necessary
increase
1 g
of
the
water
to
specic
temperature
by
1 °C;
of
other
energy
of
water
is
higher
than
that
of
substances
limits
the uctuations
in
the
temperature
of
breaks
organisms
hydrogen
capacity
this
this
thermal
heat
common
bonds
and
the
environment
of
those
that
live
in
between
water
high
latent
heat
of
vaporisation
water
molecules
much
thermal
needed
change
to
to
energy
cause
water
is
water
loss
to
of
(e.g.
vapour
water for
in
sweating)
lot
of
high
latent
heat
of fusion
much
thermal
needed
water;
from
reactive
to
much
water
water
energy
change
splits
is
is
ice
stay
transferred
when
it forms
ice
to form
to
in
as
a
energy
so
are
by
of
a
is
in
habitats
pools)
too
shallow
(e.g.
does
aquatic
ponds,
not
rock
evaporate
quickly
water
tends
liquid,
membranes
raw
as
water
evaporate
cells
damaged
and
efcient
quantities
water
to
is
thermal
needed
small
cooling
transpiration
to
cell
not
ice
crystals
material for
+
hydrogen
ions
(H
)
and
photosynthesis
−
hydroxyl
ions
(OH
)
provides
and
hydrogen
ions
electrons for
photosynthesis
and
respiration
used
in
hydrolysis
reactions,
density
ice
is
less
dense
than
water
ice
that forms
breaks
and
at
e.g.
cell
kills
risk
digestion
in
cells
membranes
cells;
organisms
of freezing
‘anti-freeze’
make
provides
aquatic
not
need
lower freezing
water
cannot
into
smaller
a
be
compressed
volume
as
hydrostatic
animals,
turgidity
which
cohesion
hydrogen
bonds
molecules
hold
together
water
on
an
water
–
insulation for
cytoplasm
in
in
organisms
beneath
in
sea
worms
plant
provides
supports
water
skeleton
e.g.
anemones,
high
do
point
aquatic
incompressible
so
developed
skeleton
acts
of
highly
compounds
ice oats
that
buoyancy for
organisms
cells,
support
columns
xylem
of
gives
some
surface
tension
organisms
surface
of
live
–
on
water
5
1.3
Carbohydrates
–
sugars
Carbohydrates
Learning outcomes
are
organic
compounds
that
have
the
following
properties,
they:
On
completion
should
be
able
of
this
section,
you

contain

have
elements
C,
H
and
O
to:
the
general
formula
C
(H
O)
x

describe
the
structure
of
the

form
of
include
state
and
the
β
monosaccharides
(e.g.
y
glucose),
disaccharides
(e.g.
sucrose)
glucose
and

2
ring
difference
between
polysaccharides
(e.g.
starch,
glycogen
and
cellulose).
a
glucose
Simple

describe

explain
the
structure
of
sugars
sucrose
Simple
sugars
are
monosaccharides,
which
have
the
formula
C
(H
x
the
relationship
which
the
structure
and function
H
6
and
of
O
12
two
foc us
as
they
are
donate
aldehyde
and
four
,
ve,
six
or
seven.
Glucose
with
the
in
y
formula
is
an
example.
Glucose
molecules
exist
as
straight
chains
and
as
6
ring
the
reducing
agents
electrons from
ketone
often
forms
the
–OH
two
sugars
three,
Most
about
Simple
is
sucrose.
rings.
S tudy
x
of
C
glucose
O)
2
between
below
of
is
dependent
carbon
forms
different
glucose
atom
the
ring
glucose
properties
at
in
on
and
the
ring
β
1.
(beta)
The
with
polymerised
roles
(see
form
position
position
and
are
the
to
page
as
of
shown
the
two
the
form
–H
and
forms
–OH
here.
There
–OH
are
a
above
groups
(alpha)
the
are
with
ring.
macromolecules
These
with
very
8).
their
groups. They
6
CH
OH
6
2
CH
OH
2
are
known
as
reducing
sugars.
O
C
C
5
O
5
H
OH
H
H
H
H
C
4
C
C
C
4
OH
H
OH
HO
OH
Link
H
OH
H
2
C
C
C
3
2
3
H
n
solution,
glucose
is
in
the
the
straight
ring form.
n
the
chain form
an
giving
as
a
the
straight
sugar.
For
its
agent.
group
page
group
molecule
reducing
ketone
see
aldehyde
and
more
is
is
ability
a
to
act
has
a
reducing
information
on
this
are
component
Glucose
other
is
and
Trioses
at
and
RNA)
in
are
six
hexoses
carbon
are
water
in
fructose
soluble.
the

to
and
more
these
detail
of
in
blood
and
It
of
is
and
so
is
an
galactose.
the
form
animals.
It
Glucose
of
is
example
is
of
a
a
hexose
polar
carbohydrate
readily
taken
molecule
that
up
sugar;
by
and
is
cells
and

polymerised

used
as
a
a
source
to
raw
and
of
form
energy
a
in
respiration
polysaccharide
material
to
make
other
for
energy
storage
compounds,
e.g.
disaccharides
common
monosaccharides
that
you
will
come
across
are
pentoses
acids
will
on
have
ve
carbon
atoms
and
trioses
that
have
three.
be
page
62.
the
organisms
provide
Complex
sugars
in
Monosaccharides
respiration
atoms
molecules
nucleic
important
metabolism
has
transported
that
looked
a and β glucose. The numbers refer to the carbon atoms
therefore
Other
nucleotides
(DNA
glucose
metabolised:
Link
of

chain
Fructose
also
glucose
exposed
18.
Pentoses
OH
and
Figure 1.3.1
form
H
transition

between
OH
are
joined
together
to
form
complex
sugars
known
as
photosynthesis, for
disaccharides.
The
diagram
from
glucose
shows
how
this
happens
in
plant
cells
that
example.
make
sucrose
water
is
glucose
is
removed
molecule
known
reaction
covalent
6
as
a
that
and
water
and
is
and
an
C2
glycosidic
because
bond
so
of
the
bond
is
fructose.
oxygen
fructose
and
formed.
therefore
the
The
very
In
‘bridge’
the
reaction,
forms
molecule.
type
of
The
reaction
glycosidic
strong.
a
between
bond
molecule
C1
bond
is
is
a
a
of
of
the
that
forms
condensation
type
of
Module
CH
1
OH
2
CH
OH
S tudy
2
foc us
O
O
H
H
H
H
When

H
OH
H
HO
CH
OH
Benedict’s
2
f
H
OH
OH
sucrose
is
boiled
solution
with
is
nothing
hydrolysed
by
happens.
reacting
H
with
H
hydrochloric
acid
or
the
enzyme
O
2
CH
sucrose
HO
HO
OH
sucrase
then
the
glucose
and
OH
2
CH
fructose
OH
released
react
with
2
O
O
H
H
Benedict’s
H
solution
to
give
a
colour
H
change.
H
OH
H
HO
See
page
18 for
more
details.
HO
O
CH
OH
2
glycosidic
H
OH
OH
bond
H
between
C1
Figure 1.3.2
In
fact,
sucrose
reaction
is
the
of
and
glycosidic
makes
bond
transport
to
is
and
a
formed
as
as
slower
way
its
Sucrose
is
and
polar
the
are
a
the
but
shown.
not
sugar
less-reactive
than
that
CH
of
is
and
available
to
formed
in
react.
for
glucose
by
but
It
transport
in
not
lack
18).
for
as
form
of
may
in
1.3.2.
involve
plants
groups
This
page
Figure
does
soluble,
ketone
(see
sugar
shown
formation
water
aldehyde
non-reducing
have
in
complex,
Sucrose
fructose
sucrose
advantage
never
more
water
phloem.
glucose
is
much
elimination
in
and C2
Formation of the disaccharide, sucrose
The
the
transport
reactive
as
the
reactivity
be
plants
an
as
the
animals.
OH
2
CH
OH
2
O
O
H
H
H
H
H
OH
H
HO
HO
O
CH
OH
2
H
OH
OH
H
H
O
2
CH
OH
2
CH
OH
2
O
O
H
H
H
H

H
OH
H
HO
HO
HO
OH
CH
OH
2
H
OH
OH
glucose
Figure 1.3.3
H
fructose
When the glycosidic bond in sucrose is broken by the addition of water, two
monosaccharides are formed
The
a
type
of
reaction
hydrolysis
in
which
water
is
added
to
break
a
glycosidic
bond
is
reaction .
Summary questions
1
Dene
the following
monosaccharide;
condensation;
2
Use
a
simple
and
β
terms:
hexose;
4
carbohydrate;
disaccharide;
glycosidic bond;
Make
simple
breakage
Make
of
a
diagrams
a
to
glycosidic
show
bond
the formation
between
two
and
hexoses.
hydrolysis reactions
diagrams
to
show
the
difference
5
Make
6
Suggest
a
list
of
the features
of
carbohydrates.
between
why
glucose
is
transported
in
animals,
but
glucose.
sucrose
3
of
table
glucose
to
and
compare
the
structure
is
transported
in
plants.
and functions
sucrose.
7
1.4
Complex
carbohydrates
Glucose
and
other
monosaccharides
are
used
as
monomers
to
make
Learning outcomes
polymers
and
On
completion
of
this
section,
for
be
able
describe
polysaccharides ,
for
cell
the
structures
monomers.
Figure
1.4.1
shows
of
of
an
existing
chain
with
the
are
used
for
Polysaccharides
a
glucose
formation
energy
are
storage
made
monomer
added
from
to
starch,
of
a
glycosidic
the
bond.
the
O
polysaccharides:
O
O
glycogen
O
and
which
walls.
to:
end

as
cellulose
you
many
should
known
making
O
OH
cellulose
H
O
2

explain
the
the
relationship
structure
between
and function
of
the
O
O
O
O
O
O
O
OH
polysaccharides.
addition
growing
of
glucose
end
of
to
a
1,4
amylose
glycosidic
between C1
bond
and C4
Did you know?
Figure 1.4.1
The formation of a glycosidic bond between the end of a polysaccharide and
a glucose monomer
Cellulose
organic
is
the
most
compound
common
on
Earth. The
Glycosidic
bacteria, fungi
and
termites
and
recycle
it
as
important
carbon
role
in
dioxide
the
bonds
that
form
between
C1
at
the
end
of
the
growing
chain
that
play
an
C4
of
glycosidic
biosphere.
the
unbranched
glucose
bond
From
If
chain
monomer
that
the
forms
rst
glycosidic
energy
glucose
bonds.
amylose

amylopectin

glycogen
and
amylopectin
therefore
to
carbon
make
joining
that
glucose
formed.
A
6
is
being
these
a
branching
are
point
growing
another
glucose
added
monomers
branching
on
added
amylopectin
but
has
to
the
is
points
monomers
known
The
is
can
in
formed
chain.
chain
are
added
a
together
.
by
type
1,6
form
this
as
1,4
way
of
There
a
glycosidic
glycosidic
with
an
adding
more
are
bond.
1,4
three
polysaccharides:

Amylose
is
monomer
monomer
bonds
storage
all
has
many
more
more
are
1,6
forms
of
starch.
glycosidic
branches.
Glycogen
bonds
Glycogen
than
is
is
very
similar
amylopectin
sometimes
called
to
and
‘animal
starch’.
The
three
energy
storage
polysaccharides
are
made
from
a
glucose
monomers.
Cellulose
not
Polysaccharide
used
Monomer
Glycosidic
a
1,4
is
for
bonds
a
long
chain
energy
molecule
storage,
but
for
made
from
making
Structure
the
β
glucose
cell
monomers.
walls
of
It
is
plants.
Role
starch
amylose
glucose
unbranched
chain
amylopectin
a
glucose
1,4
and
1,6
a
glucose
1,4
and
1,6
right-handed
branched
not
glycogen
–
a
8
β
glucose
1,4
storage
in
plants
energy
storage
in
animals,
chain
helix
branched
chain,
branched than
cellulose
energy
helix
more
amylopectin
fungi
and
unbranched
grouped
straight
plant
chain
some
into
cell
bacteria
bundles
walls
within
Module
1
Cell
and
molecular
biology
polysaccharides
S tudy
To
help
you
similarities
the
foc us
understand
and
biological
simple
the
differences
polymers,
diagrams
of
between
make
some
amylose,
amylose
amylopectin
CH
OH
2
CH
2
OH
annotate
2
O
O
their
H
H
H
H
OH
OH
OH
etc.
and
them
structure
glycogen
with
and
points
about
and function. You
can
etc.
O
do
O
O
the
same for
proteins
and
nucleic
O
acids.
OH
OH
OH
1,4
glycosidic
bond
glycogen
CH
OH
2
O
H
H
etc.
H
OH
O
1,6
glycosidic
bond
O
H
CH
OH
CH
2
OH
OH
CH
2
CH
2
O
H
O
H
H
O
H
H
H
H
etc.
H
H
H
H
OH
OH
OH
OH
O
O
H
O
OH
H
OH
2
O
H
etc.
OH
Summary questions
O
OH
H
O
OH
H
OH
1
Figure 1.4.2
Explain
why
starch
and
glycogen
Two polysaccharides: amylose and glycogen
make
suitable
energy
Structure
and function
molecules for
storage
suitable for
and
cell
cellulose
walls
of
is
plant
cells.
The
storage
compact.
polysaccharides
Amylose
and
are
insoluble
amylopectin
are
in
water
,
stored
in
unreactive
plant
cells
and
as
starch
2
grains
and
glycogen
is
stored
in
animal
cells
as
smaller
granules.
Draw
a
diagram
formation
amylopectin
glucose
can
and
be
Alternate
β
are
to
glycogen
added
glucose
or
have
branches
removed
molecules
as
are
they
required
arranged
have
by
at
a
many
places
a
growing
cellulose
molecule.
180°
This
helix,
with
many
projecting
–OH
groups
on
bond
to
point
in
make
to
each
other
as
hydrogen
gives
a
straight
chain,
bonds
molecules
with
adjacent
bonded
cellulose
together
by
both
sides
molecules.
hydrogen
Find
of
the
chain
that
is
very
strong.
Microbrils
are
in
a
criss-cross
pattern
to
provide
even
a
new
branching
glycogen.
out
bonds
A
bundle
forms
the
arranged
in
more
names
of
the
i
ii
a
a
polymer
of
polysaccharide
of
of
two
or
more
monomers;
a
plant
components
of
plant
cell
walls
cell
other
walls
the
to
iii
microbril
show
glycosidic
not
made
cellulose
1,6
they
fructose;
form
a
where
following:
a
of
cell.
3
added
to
As
than
cellulose;
iv
cell
wall
strength.
components
of
bacteria
and
fungi.
4
Explain
how
glycogen
and
macrofibril
cellulose
are
suited
to
their
microfibril
functions.
CH
OH
H
CH
OH
2
H
OH
H
OH
OH
H
H
O
H
etc.
OH
2
H
OH
H
H
OH
H
H
O
H
H
H
OH
O
H
H
CH
OH
2
Figure 1.4.3
H
O
H
OH
H
Close packing of cellulose
etc.
molecules in a microbril and the pattern
CH
OH
of microbrils in a cell wall
2
9
1.5
Lipids
Lipids
are
organic
compounds
composed
of
the
same
elements
as
Learning outcomes
carbohydrates,
In
On
completion
of
this
section,
addition
be
able
describe

a
the
molecular
good

of

how
a
the
of
are
energy
molecular
why
of
as
higher
same
ratio
structure
of
as
hydrogen
to
oxygen.
polysaccharides
The
two
groups
of
lipids
described
with
here,
biological
main
phospholipids ,
also
The
groups
glycerol
of
attached
have
have
the
These
phosphate
carboxylic
to
units.
same
acid
form
and
group
ester
of
units
basic
are
structure
fatty
with
acids.
nitrogen-containing
fatty
acids
reacts
groups
with
the
–OH
bonds.
Triglycerides
phospholipids
the
and
three
attached.
are
Each
suitable
much
structure
phospholipid
explain
and
Phospholipids
triglycerides
sources
describe
a
the
structure
triglyceride
explain
have
have
to:
glycerol
of
not
monomers.
triglycerides

they
do
you
repeated
should
but
they
component
membranes.
are
triglyceride
different
1.5.1,
as
molecule
fatty
they
acids,
have
the
full
carbon
chain.
Saturated
carbon
atoms
in
Figure
the
carbon
three
As
1.5.1,
with
chain
identical
lipids
polar
have
and
are
storage
tissue)
in
rich
oils.
released
as
as
They
are
are
the
and
fatty
have
acids
bond
are
of
more
oil
in
during
mass
in
carbon
of
fat
Seeds
carbohydrate
they
or
as
are
in
have
acids.
are
not
(adipose
especially
storage
more
B
along
long-term
tissue
because
much
between
atoms
fatty
Figure
the
such
excellent
energy
molecules
to
There
in
triglycerides
groups
special
A
bonds
different
make
respiration,
of
double
–OH
for
attached
Some
plants.
efcient
reduced
as
between
than
stored
acids.
unsaturated,
mixture
rather
fatty
such
any
are
hydrogens.
a
three
acids ,
hydrogens
T
riglycerides
highly
same
of
not
have
water
.
oxidised,
from
fewer
droplets
oils
they
When
than
and
do
double
groups
in
glycerol
fatty
others
molecules.
and
acids
therefore
–CH
of
saturated
Some
one
acids;
many
Fats
carbohydrates
fatty
least
and
fatty
animals
hydrogens.
at
are
complement
chain.
insoluble
energy
in
the
consists
some
than
of
all
energy
those
is
protein.
H
H
H
C
C
glycerol
C
H
H
H
H
O
A
H
C
C
O
three fatty
H
C
acids
C
O
B
H
C
C
H
3H
O
2
H
H
C
O
O
C
O
triglyceride
H
C
O
C
O
H
C
O
C
H
Figure 1.5.1
Glycerol and three fatty acids combine to form a triglyceride
O
C
‘water-hating’
O
tails:
C
phospholipid
O
C
‘water-liking’
head:
Figure 1.5.2
P
=
phosphate
=
choline
hydrophilic
A phospholipid is composed of glycerol, two fatty acids and a phosphate-
containing part
10
hydrophobic
C
Module
1
Cell
and
molecular
biology
Phospholipids
Each
phospholipid
Attached
often
to
to
that
phosphate
not
one
a
in
on
top
with
of
T
wo
to
layers
of
This
is
the
biological
Fat
Fat
need
we
need
stored
is
food
is
no
fat
food
and
balance
become
experience
over
a
30
a
food
result
per
a
good
cent
be
tails
a
fatty
a
in
that
and
This
acids
are
region.
either
If
in
form
hydrophilic
a
layer
heads
centre.
with
regions
covered
the
the
acids.
group
hydrophilic
will
with
bilayer
fatty
choline.
have
in
bilayer
the
ill
from
diet
health.
organs,
for
excess
a
central
contact
is
the
on
page
are
two
the
also
we
a
with
water
.
structure
of
36.
would
good
than
population
there
is
being
and
can
of
good
people
in
do
of
and
is
there
There
classify
body
a
variety
people
mass
index
as
20%
recommended
mass
fat
are
of
ways
obese
or
(BM)
including:
more
mass for
to
above
height;
greater
than
the
body
30.
when
negative
their
diet.
as
fat
not
food
obesity
obese
so
at
energy
enough
epidemic
as
into
in
as
these
when
are
excess
in
Did you know?
we
soluble
energy
protein
than
classied
fat
periods
are
that
known
decient
obtain
the
more
are
people
Many
an
be
acids
are
provider
scarce
have
D,
Humans
store
obese.
they
during
they
balance
they
countries
is
and
fatty
vitamin
energy
food
even
fact
as
carbohydrate
energy
or
in
else
insulation.
when
energy
overweight
of
is
providing
more
many
such
otherwise
Fat
periods
positive
There
anything
thermal
convert
use
thing.
vitamins,
shortages;
in
will
as
(‘water-hating’)
spheres
form
two
phosphate
two
molecule
hydrophilic
which
the
a
phospholipids
phospholipid
Some
in
and
have
of
and
is
such
whereas
the
tiny
will
make
and
can
who
group,
hydrophobic
two
is
During
People
As
fat
suffer
scarce.
may
diet
cannot
have
glycerol
glycerol
and obesity
acids.
energy
eat.
the
protecting
or
storing
we
and
for
little
and
and
of
human
to
form
the
of
of
hydrophobic
layer
phospholipids
fatty
vitamins
a
will
and
region
basis
which
essential
and
membranes,
the
makes
single
or
in the diet
in
consists
groups
soluble,
This
a
water
water
hydrophobic
–OH
water
region
water
the
attracted
is
water
.
(‘water-liking’)
contact
the
nitrogen-containing
‘head’
soluble
molecule
of
or
to
with
very
obese.
Summary questions
1
Dene
the following
terms:
fatty acid; glycerol; ester bond; saturated fatty
acid; unsaturated fatty acid; hydrophilic; hydrophobic; monolayer; bilayer ;
obesity
2
Make
a
table
to
phospholipids.
as
3
the
differences
Explain
term
compare
why
the
(Remember
between
triglycerides
structure
to
include
and functions
what
they
of
have
triglycerides
in
common
as
and
well
them.)
are
efcient
sources
of
energy
and
good for
long-
storage.
4
Explain
5
Find:
i
the
the
importance
names
of
of
the
phospholipids
two
in
essential fatty
organisms.
acids
in
the
BMI
human
diet;
ii
Category
the
below
fat
6
soluble
The
body
vitamins;
mass
iii
index
the
risks
(BM)
is
to
health
calculated
body
of
using
mass
20
underweight
obesity.
in
the following formula:
20–35
acceptable
25–30
overweight
over
30
obese
over
40
very
kg
_________________
BM
=
2
(height
a
Calculate
A
the
1.65 m,
b
Use
c
What
the
BM for
45 kg;
table
advice
to
B
the following
1.63 m,
identify
would
you
in
people:
64 kg; C
the
give
metres)
1.65 m,
appropriate
these four
75 kg;
D
1.45 m,
categories for
each
75 kg.
person.
obese
people?
11
1.6
Proteins
Learning outcomes
(1)
Amino
Proteins
On
completion
of
this
section,
acids
are
polypeptide
should
be
able
describe
the
structure

state
of
that
consists
of
an
made
from
unbranched
one
or
chain
of
more
polypeptides.
amino
acids.
A
There
are
20
to:
different

macromolecules
you
generalised
amino
there
they
all
types
share
of
amino
the
same
acid
that
cells
molecular
use
to
structure
make
as
proteins.
shown
in
However
,
Figure
1.6.1.
acids
are
20
different
H
amino
acids
used
to
H
make
group
O
proteins

explain
how
amino
acids
differ
H
OH
R
from
one
another
residual

describe
the formation
Figure 1.6.1
breakage
of
a
peptide
group
and
A generalised amino acid molecule
bond.
All
amino
carboxylic
and
a
acids
acid
group
hydrogen
the
group
the
generalised
a
group.
that
atom
is
have
is
carbon
Attached
specic
then
the
then
–CH
central
to
amino
the
to
the
atom,
the
central
type
acid
amino
an
is
of
atom
amino
glycine,
acid
is
amine
is
acid.
which
alanine
group
a
a
hydrogen
If
it
is
(see
and
is
the
atom
another
smallest.
Figure
1.6.2).
If
In
3
Amino
acid
amino
acid
this
Three-letter
group
R
is
known
as
group
R
for
residual.
Comments
abbreviation
glycine
gly
–H
smallest
amino
many found
collagen
close
methionine
met
–CH
–CH
2
–S–CH
2
rst
to
allow for
packing
amino
acid
primary
sequence
when
polypeptide
–CH
a
is
produced
on
ribosome
(see
page
ala
of
2
every
alanine
acid;
in
a
71)
non-polar
R
non-polar
R
which
a
group
3
glycine
H
CH
3
H
O
H
N
O
phenylalanine
phe
N
H
OH
H
CH
OH
H
2
has
structure formed
hydrolysis
condensation
H
atoms
alanine
O
2
2
cysteine
dipeptide
cys
–CH
–SH
sulphur-containing
2
H
O
H
CH
3
H
R
group; forms
O
covalent disulphide
N
H
OH
peptide
H
The formation and breakage
of a peptide bond
bonds
between
parts
H
bond
12
of
H
carbon
Figure 1.6.2
group,
ring
of
a
polypeptide or
between
polypeptides
Module
When
the
two
amino
acids
C
of
the
carboxylic
group
of
the
other
forms
a
(see
tripeptide.
A
are
joined
group
of
Figure
together
one
1.6.2).
polypeptide
a
amino
The
peptide
acid
addition
consists
of
bond
with
ten
of
or
the
forms
N
of
another
more
linking
the
Cell
hormone
molecular
biology
Did you know?
The
acid
acids.
articial
200
times
dipeptide
antidiuretic
and
amine
amino
amino
1
Phe
Gln
Asn
Cys
Pro
NH
Ile
Gln
Asn
Cys
Pro
NH
sweetener
sweeter
of
two
aspartame
than
amino
sugar.
t
is
is
a
acids.
2
oxytocin
2
Figure 1.6.3
Two nonapeptides (with nine amino acids) that are biologically active.
represents the N terminal of the peptide; the opposite end is the C terminal.)
(–NH
2
R
groups
The
R
properties
groups
that
of
polypeptides
project
from
and
the
proteins
central
are
chain
dependent
of:
on
Link
the
–C–N–C–C–N–C–C–N–.
Proteins
As
you
can
see
from
the
table
some
amino
acids
have
polar
groups
that
membranes
attract
water
molecules,
but
others
are
non-polar
and
do
not.
This
polypeptides
can
have
a
sequence
of
amino
acids
with
groups
part
of
Some
R
These
The
form
groups
attract
groups
form
rm
link
a
hydrophobic
phospholipid
position
–SH
to
a
to
of
each
to
react
in
negatively
to
form
to
to
link
polypeptides
or
ionic
polypeptides
together
attachments
different
form
other
cysteine
can
that
can
pass
through
the
position
of
page
page
and
66.
of
If
amino
maybe
Some
amino
the
acids
molecule.
the
substrates

signalling
receptor
is
is
form
is
a
different
positively
charged
t
in
a
important
disulphide
parts
of
a
as
two
bond.
polypeptide
act
Link
to
together
or
is
not
random.
‘pockets’
will
molecules
the
molecules,
not
areas,
t
into
as
genes
the
are
these
in
as
you
structure
function
which
‘pockets’
such
by
then
or
will
like
will
will
discover
be
function
‘pockets’
antigens
Any
the
change
charge
proteins
more
enzymes
are
information
active
in
to
page
on
them
49.
on
different
differently.
the
‘pockets’:
enzymes
hormones,
t
into
binding
sites
S tudy
in
foc us
molecules
t
to
into
the
binding
amino
distribution.
substrates,
in
The
You

36.
adjacent
These
The
polypeptide
determined
special
into
this
groups.
together
.
changed
polypeptide
have
Other

acids
sequence
proteins
on
bonds.
refer
sequence
hydrophobic
information
central
sites, for
The
more
bilayer
.
ionise
to
region
through
a
non-polar
see
R
have
means
region, for
that
pass
so
messenger
will
be
sites
acids
This
in
in
antibody
these
means
molecules
‘pockets’
that
and
the
are
not
required
to
remember
molecules.
changes
molecules,
antigens
will
not
the
such
t
and
shape
and
as
the
different
but
if
you
can
properties
the
in
the
types
of
next
it
of
amino
acids,
helps
to
explain
the
proteins
as
highlighted
section.
non-functional.
Summary questions
1
Dene
3
the following:

amino

peptide

dipeptide

tripeptide

polypeptide.
Make
from
acid
a
a
diagram
dipeptide
Give
in
5
a
three
an
cysteine.
annotated
Explain
drawing
the
of
the
importance
amino
protein
Find
of
this
the
acid
amino
an
how
a
amino
tripeptide
is formed
acid.
the
is
the
sequence
of
amino
acids
important.
names
ii
why
of:
i
some
production
of
the
two
amino
proteins
amino
acids
and
acids
that
give
are
that form
not
used
in
their functions.
acid
6
in
and
reasons
aspartame;
Make
show
bond
4
2
to
Write
short
proles
of
the
nonapeptides
antidiuretic
proteins.
hormone
and
oxytocin.
13
1.7
Proteins
Learning outcomes
(2)
Levels of organisation
A
On
completion
of
this
section,
polypeptide
Each
should
be
able
describe
the four
levels
straight
has
a
by
joining
denite
ten
or
number
more
of
amino
amino
acids
acids.
together
.
They
describe
the
proteins
in
in
a
chains
which
spontaneously
form
into
specic
are
formed
shapes.
of
The
organisation

formed
polypeptide
to:
as

is
you
table
summarises
the
levels
of
organisation.
protein
bonds
that
hold
Level of
Description
Comments
shape.
organisation
primary

sequence
of
amino
acids
determined
structure
that

position
of
disulphide
position
bonds
a-helix
β-pleated
sheet
tertiary
further folding
structure
to
of
complex
polypeptide
3D
will form
both
two
more
structure
associate
polypeptides
together
to form
the
a
right
back
a at
have
and
sheets
polypeptides
identical
and
sheet
polypeptides
a-helices
β-pleated
quaternary
a
helix
to form
some
shape
in
determines
polypeptide folds
forth
gene
protein
cysteines
these
handed
or
the
the
polypeptide forms
structure
give
of
sequence
where
secondary
by
codes for
or
can
be
different
protein
Primary
amino
structure
acids
disulphide
are
ribbon
Did you know?
folding
Some
but
proteins
no
have
beta-pleated
example
is
alpha
helices,
haemoglobin,
are
on
page
composed
beta-pleated
broin
silk
that
spun
by
is
16.
which
Some
is
almost
sheets
a
give
a
–
-helix
(the
arrows
latter
in
proteins)
– further
complex
-helices
sheets,
as
and
well
as
distinct
structure
of
example,
component
silkworms
of
of
proteins
entirely
– for
major
of
without
secondary
covered
wide
with
-pleated
regions
sheet
structure
to
structure
sheets. An
as
models
Tertiary
sequence
structure
-pleated
drawn
–
position
bonds
Secondary
and
and
and
of
spiders.
Figure 1.7.1
The three levels of
organisation of a polypeptide
14
Module
Bonds that
There

are
four
hydrogen
and
stabilise
bonds
bonds
that
form
1
Cell
and
molecular
biology
proteins
stabilise
between
polypeptides:
polar
groups,
such
as
the
dipolar
–NH
–CO

ionic
bonds

hydrophobic

disulphide
hydrogen
form
between
interactions
bonds
bond
ionised
between
between
between
amine
polar
the
R
and
non-polar
S-containing
carboxylic
side
R
acid
groups
chains
groups
of
cysteines.
groups
OH
central


CH
bonds
of
CH
2
ionic
carbon
atom

O
O
an
amino
acid
2
between
ionised
R
groups
CH
C
CH
2
2

2
hydrophobic
O
NH
CH
3
interactions
between
non-polar
R
groups
CH
Link
3
CH
CH
For
more
information
about
2
hydrogen
bonds,
see
page
4.
CH
3
disulphide
bond
(covalent)
CH
CH
2
Figure 1.7.2
After
2
The bonds that stabilise polypeptides
proteins
are
produced
inside
cells
by
the
assembly
of
amino
acids,
Summary questions
they
are
might
further
processed.
There
are
a
variety
of
ways
in
which
this
happen:
1

The
addition
composed
group
of
of
of
a
prosthetic
amino
acids;
haemoglobin
group
for
and
that
example,
is
part
haem
of
a
that
protein
is
the
not
Find
a
ribbon
protein
prosthetic
show
the
regions
Polypeptides
haemoglobin
haem

are
assembled
and
catalase
to
give
both
a
have
protein
four
its
quaternary
polypeptides
structure;
each
with
has
a
group.
Chains
of
sugar
of
the
of
it
to
secondary
catalase.
structure

diagram
lysozyme. Annotate
molecules
may
be
added
to
the
polypeptide
to
form
and
tertiary
explain
structure
quaternary
structure.
function
of
lysozyme.
Find
how
why
but
it
not
State
the
a
2
out
many
polypeptides
glycoprotein.
there

Polypeptides
may
be
cut
into
two
or
more
pieces
and
joined
are
happens
in
the
formation
of
a
surface
are
proteins
forming
hydrophobic
insoluble
in
are
soluble
hydrogen
R
groups
in
bonds
that
amylase;
insulin;
insulin.
glucagon;
Globular
the following
together
,
proteins:
as
in
water
with
hydrophilic
with
water
molecules.
exclude
water
.
Fibrous
R
groups
on
Internally
proteins
catalase;
anhydrase;
the
the functions
there
carbonic
myoglobin.
of
each
State
of
these
proteins.
are
water
.
3
Explain
the
and
the
difference
primary
its
structure
secondary
between
of
a
protein
structure.
15
1.8
Proteins
Learning outcomes
(3)
Globular
Globular
On
completion
should

be
able
explain

section,
difference
and brous
describe
of
this
the
are
soluble
in
water
and
folded
into
complex
3-D
you
to
between
proteins
molecular
haemoglobin
structure
proteins
proteins
shapes.
Fibrous
such
a
proteins
are
insoluble
in
water
and
have
simple
shapes,
to:
the
globular
of
and fibrous
its
and
cells;
and
helix.
collagen
material
structure
relate
as
Haemoglobin
is
a
between
bone.
Both
brous
cells
are
in
is
a
protein
globular
that
structures
formed
from
is
a
such
more
protein
major
as
found
component
tendons,
than
one
inside
red
of
blood
the
ligaments,
muscles
polypeptide.
its
transport
Haemoglobin
functions
Each

describe
the
molecular
a
of
collagen
and
relate
molecule
globins
to
are
A
haem
with
groups
four
carry
four
one
red
show
the
composed
the
centre
of
of
molecules
second
oxygen
it
look
not
of
made
ferrous
of
amino
temporary
this
of
acids;
that
The
)
(Fe
bond
means
oxygen.
iron
at
chemically
its
centre.
with
an
each
haemoglobin
the
shape
molecule.
of
addition
haemoglobin
oxygen
of
the
This
makes
it
making
easier
this
makes
cell.
t
blood
is
molecule lls
estimated
cell
it
easier
to
accept
the
fourth.
contains
changes
form
shape
exposing
opening
the
out
haem
from
groups
a
to
is
it
Each
–
two
a
haem
is
of
molecule.
rst
million
to
it
very
the
As
molecule
molecule
easier
accept
This
‘tense’
accept
there
can
to
of
the
accept
third
the
and
is
because
in
the
haemoglobin
form
to
a
more
oxygen.
a
that
polypeptide
about

not
polypeptides
polypeptide
as

280
four
each
molecule
makes
haemoglobin
red
is
In
haemoglobin
circle. This
blood
each
a
groups
changes
‘relaxed’
if
is
atom
forms
haem
molecule
a
group
an
oxygen
turn
within
globins.
foc us
of
sometimes
β
2+
haem
Diagrams
haemoglobin
two
its function.
different
S tudy
and
this
group.
structure
of
structure
polypeptide
molecules,
one!
each
polypeptide
helices,
but
no
has
alpha
beta-pleated
sheets
Did you know?

Haem
group
is
–
an
a
example
part
of
a
of
a
polypeptide
prosthetic
protein
molecule
2
Fe
that
is
not
Proteins
that
are
made
like
not
this,
of
amino
acids.
containing
made
of
amino

parts
acids,
Figure 1.8.1
are
called
conjugated
haem
polypeptide
Haemoglobin has quaternary structure
proteins.
Collagen
Collagen
is
cartilage,
an
tendons,
organisation
A
molecule
form
triple
acids
S tudy
R
foc us
Remember
more
than
that
one
quaternary
any
protein
polypeptide
structure.
that
has
has
helix.
with
of
be
them.
wound
The
to
form
a
it
as
is
made
network
is
triple
of
the
third
not
take
together
helix
The
of
not
bres.
bres
as
joined
of
in
each
of
has
of
bone,
levels
of
the
helices
do
a
helices
between
structure
covalent
weakness
form
amino
smallest
the
bonds
tertiary
by
that
to
1000
means
hydrogen
triple
lines
other
about
This
the
skin,
several
polypeptides
together
the
no
has
to
haemoglobin.
Glycine
space.
many
again
are
of
around
acid.
much
ends
there
identical
form
are
those
consisting
amino
up
toughness
Collagen
as
wound
long,
folded
The
so
three
and
helices
provides
same
are
are
that
muscles.
the
These
every
does
tightly
within
and
quite
polypeptides
triple
haemoglobin.
not
helices.
glycine
so
protein
ligaments
are
collagen
The
(–H)
coincide
16
that
left-handed
group
can
extracellular
of
bonds
not
where
Module
the
bres
may
structures
pulling
break.
such
as
This
tendons
arrangement
that
have
makes
high
collagen
tensile
suitable
strength
and
1
Cell
for
biology
Link
Cellulose
collagen
similar
b
molecular
resist
forces.
a
and
is
is
a
a
polysaccharide
protein,
but
and
both
structural features
have
and
covalent
functions. Try
comparing
their
bond
structure
and function
Summary
question
8
by
completing
below.
glycine
300
Figure 1.8.2
nm
a The triple helix of collagen; b triple helices are joined together to form
collagen bres
Figure 1.8.3
Collagen bres from human skin. Notice the characteristic banding pattern
that is visible at this magnication in an electron microscope (the bres are 300 nm wide).
Summary questions
1
Explain
why
following:
protein
haemoglobin
globular
with
is
protein;
quaternary
an
example
conjugated
of
5
the
protein;
Explain
its
how
the
structure
of
collagen
is
related
to
its
structure
of
haemoglobin
is
related
to
Draw
a
table
to
and functions
compare
of
the
structure,
haemoglobin
and
distribution
collagen.
transport functions.
Explain
why
collagen
is
an
example
of
a brous
Collagen
and broin
proteins.
State
how
(see
their
page
14)
are
structures
both brous
differ.
Find
some
computer-generated
haemoglobin
protein.
4
the
structural functions.
7
3
how
structure.
6
2
Explain
8
show
their
Draw
a
of
collagen
and
of
annotate
them
to
structure.
table
function
and
models
to
compare
cellulose
and
the
structure,
location
and
collagen.
17
1.9
Qualitative
Learning outcomes
biochemical
Test for
The
On
completion
should

be
able
describe
starch;
of
this
section,
tests
starch
reagent
for
the
starch
test
is
the
iodine
in
potassium
iodide
solution
you
(known
simply
as
1
The
substance
2
If
iodine
solution).
to:
the
biochemical
reducing
sugars;
to
be
tested
may
be
a
solid
or
a
liquid.
tests for
non-
solid,
place
a
sample
of
the
substance
on
a
white
tile
or
in
a
Petri
dish.
reducing

state
sugars;
the
positive
results for
Colour
proteins;
these
change
and
lipids
tests.
with
3
If
4
Use
liquid
place
into
a
test-tube.
negative
iodine
a
dropping
pipette
Result
Explanation
positive
iodine
starch
starch-iodine
to
add
iodine
solution.
solution
yellow-orange
or
no
to
blue-black
blue
change;
remains
iodine
solution
yellow-orange
present
negative
no
no
starch
The
foc us
to
call
the
reagent for
test
‘iodine
solution’
the
centre
complex
iodine
to
of
the
which
bind
helix
has
a
of
amylose
blue-black
to form
colour
to
for
the
solution
sugars
reducing
of
copper
sugar
test
is
Benedict’s
solution
–
an
sulphate.
the
1
starch
starch for
reducing
reagent
alkaline
Remember
to
present
Test for
S tudy
binds
If
the
substance
to
be
tested
of
the
is
solid,
make
a
solution
with
water
.
not
3
2
Put
about
1 cm
test
solution
into
a
test-tube
and
add
an
equal
‘iodine’.
volume
3
Boil
4
W
atch
(The
with
change on
Benedict’s
boiling
a
Benedict’s
water
bath
carefully
test-tube
placing
Colour
in
of
into
a
for
may
water
be
solution.
(do
not
colour
put
bath
heat
directly
with
a
Bunsen
burner).
changes.
into
with
a
water
boiling
Result
Explanation
positive
sugar
bath
at
about
80 °C
rather
than
water
.)
solution
2+
blue
to
green/yellow/
reduces
copper(II)
ions
)
(Cu
in
Benedict’s
solution
+
orange/red
with
to
a
reducing
sugars
change;
solution
Benedict’s
remains
necessarily
(Cu
)
to form
a
precipitate
of
copper(I)
glucose)
negative
no
reducing
sugars
present
to
react
with
copper(II)
ions
blue
Test for
If
a
test
may
is
18
ions
oxide
(not
no
copper(I)
present
precipitate
non-reducing
substance
contain
sucrose
1
Divide
2
T
est
A
gives
a
sugars
negative
non-reducing
(see
the
page
test
with
sugars.
result
The
with
only
the
reducing
common
Benedict’s
into
two
solution
equal
as
parts,
above.
A
test
non-reducing
7).
solution
sugar
and
B.
it
sugar
Module
3
Add
a
few
drops
of
dilute
hydrochloric
acid
to
B
and
boil
for
a
1
Cell
and
molecular
biology
few
minutes.
4
Cool
the
sodium
5
When
A
B
A
B
–
–
–
add
dilute
test
to
sodium
(beware,
with
the
Benedict’s
boiling
will
solution
as
solution
or
solid
zz).
above.
Result
Explanation
negative for
green/yellow/
sugar,
reducing
no
negative for
change
change
and
reducing
positive for
orange/red
no
hydroxide
latter
solution
change
blue
Test for
The
change on
Benedict’s
no
–
and
carbonate
neutralised,
Colour
with
test-tube
hydrogen
hydrochloric
non-
sucrose
sugar
reducing
both
reducing
non-reducing
no
sugars
acid
acts
to fructose
for
reducing
sugars
hydrochloric
present
acid to
the
catalyst
protein
test
is
biuret
solution
(a
solution
of
If
the
substance
Place
3
Add
1 cm
of
to
the
same
should
be
tested
is
solid,
make
a
solution
with
record
water
.
may
test
solution
in
a
test-tube.
in
carry
the
and
be
side
Colour
to
volume
of
biuret
solution
and
mix
by
shaking
the
these
all
on
t
Make
tests for
is
the
them
easy
sure
you
details
in
as
you
the
to forget
tube
procedures.
side.
change
with
Result
Explanation
S tudy
biuret
out
lab.
learn
tested
practical
from
sugars
foc us
examination.
the
using
non-reducing
copper
3
2
both
hydroxide).
yourself
1
hydrolyse
are
after
any
S tudy
sodium
to
that
even
hydrolyse
You
and
a
glucose
sugars
proteins
reagent
sulphate
as
and
foc us
solution
What if samples contain both reducing
blue
to
violet/purple/
positive
a
coloured
complex forms
where
and non-reducing sugars? What
lilac
there
are
peptide
bonds
would be the results for samples A and
B? Attempt Summary question 4 and
no
change
to
the
blue
negative
no
peptide
bonds
present
see if you are right.
colour
Summary questions
Test for
lipids
1
Lipids
as
are
insoluble
ethanol.
This
in
test
water
,
makes
but
use
they
of
are
this
soluble
in
organic
solvents
Make
a
summary
these
biochemical
2
Crush
any
solid
some
ethanol.
If
test
the
material
to
be
tested
in
a
pestle
and
mortar
and
add
test
is
a
liquid
just
show
tests. Use
add
some
ethanol
and
shake
headings:
(starch,
method;
negative
to
column
biochemical
reagent;
substance
to
fact.
the following
1
table
such
etc.);
positive
result;
result.
dissolve.
2
3
Pour
off
the
test-tube
of
ethanol,
water
which
(do
not
may
have
dissolved
some
lipids,
into
a
Make
to
mix).
a ow
test
a
sample
tissue for
reducing
Change when
adding
Result
You
have
Explain
cloudiness
–
positive
the
ethanol
dissolves
the
lipid;
emulsion
addition
to
water
the
lipid
throughout
the
water
sugars.
a
tiny
particles
–
an
Some
solution
no
lipid
present
to
glucose
that
is
a
why
the
and fructose.
be
used
Benedict’s
to
conrm
test
this.
plant
material
glucose
and
contains
sucrose.
Explain
emulsion
how
negative
of
as
both
change
storage
non-
is
4
dispersed
no
plant
and
how
on
cannot
an
of
reducing
show
water
mixture
white
to
Explanation
3
ethanol to
chart
be
dispersed
test
you
to
can
use
conrm
the
Benedict’s
this.
19
1.
10
Quantitative
The
Learning outcomes
biochemical
tests
in
biochemical
On
completion
should
be
able
of
this
section,
here
you
Section
is
attempt
1.9
present
to
make
explain
how
to
carry
test for
out
a
qualitative.
not
how
results
much
They
is
tell
you
present.
quantitative
to
that
The
varying
the
tests
described
degrees.
The
reducing
nal
reducing
how
quantitative
to
carry
test for
out
Benedict’s test
semi-
sugars
describe
all
to:
quantitative

but
the
Semi-quantitative

are
tests
is
green
is
much
colour
sugar
then
change
is
the
with
present
in
Benedict’s
a
test
concentration
test
sample.
of
the
gives
For
an
idea
example,
reducing
sugar
if
is
of
how
the
very
much
nal
low;
colour
if
red
it
a
higher
.
One
way
to
improve
this
estimate
is
to
make
up
a
series
starch.
of
colour
standards
using
a
glucose
solution
and
Benedict’s
solution.
3
1
T
ake
20 cm
of
a
stock
glucose
solution
of
known
concentration,
–3
e.g.
2
100 g dm
Make
a
series
of
dilutions
from
this
stock
solution,
e.g.
50.0,
20.0,
–3
10.0,
5.0,
3
Place
equal
4
Carry
and
5
out
1.0,
the
the
Y
ou
now
have
of
the
Benedict’s
or
boiling
test-tubes
permanent
S tudy
0.1 g dm
volumes
heating
Cool
0.5,
test
all
and
dilutions
as
the
in
into
Section
test-tubes
keep
labelled
them
1.9
for
(maybe
test-tubes.
(using
the
same
take
equal
volumes
length
of
photographs
time).
for
a
record).
a
set
of
colour
standards.
foc us
–3
Concentration of
t
is
important to
glucose/g dm
Result on testing
with
Benedict’s
carry out the
solution
procedure
when
in
exactly the
making the
that you
colour
know the
same way
as
standards
so
results
are valid.
you do them differently you
be
sure
about the
estimates of the
50.0
dark
red
20.0
red
10.0
orange
f
cannot
accuracy of your
concentrations.
5.0
yellow
1.0
6
green
0.5
light
0.
1
blue
Carry
out
exactly
7
Cool
the
the
the
the
Benedict’s
same
test
procedure
test-tube
concentration
and
of
on
as
place
a
solution
when
next
reducing
green
to
sugar;
of
making
the
the
the
the
colour
test
substance
colour
standards
answer
may
be
using
standards.
to
a
determine
range,
–3
e.g.
A
S tudy
test
between
like
this,
1.0
and
which
5.0 g dm
can
give
you
an
estimate
of
the
concentration,
is
foc us
semi-quantitative.
Summary
question
1
you
some
some fruit
gives
juices
results from
testing
for
sugar. Answer
reducing
question
20
before
the
continuing.
This
test
weighing
against
in
can
it
the
be
on
a
improved
balance.
concentration
any
test
substance
graph.
Y
ou
can
try
can
this
by
The
of
be
for
removing
masses
glucose.
the
The
determined
yourself
in
precipitate,
recorded
can
be
drying
plotted
concentration
by
taking
Question
4
an
on
of
it
on
a
25.
on
then
graph
reducing
intercept
page
and
sugar
the
Module
Quantitative test for
T
o
make
can
the
make
a
iodine
series
test
of
1
Cell
and
molecular
biology
starch
for
starch
dilutions
of
quantitative
a
starch
we
solution.
3
1
T
ake
20 cm
of
a
stock
starch
solution
of
–3
known
2
Make
concentration,
a
series
solution,
e.g.
of
e.g.
100 g dm
dilutions
50.0,
10.0,
from
5.0,
this
1.0,
stock
0.5,
0.1,
0.05
–3
and
3
0.01 g dm
Place
equal
labelled
4
Add
the
each
heat
5
same
these
Place
as
each
a
with
optical
are
percentage
Plot
the
of
dilutions
iodine
(remember
it
is
Benedict’s
test-tube
the
(results
of
volume
test-tube
detects
6
volumes
into
test-tubes.
into
a
as
to
necessary
to
solution).
colorimeter
,
density
recorded
solution
not
of
the
Figure 1.10.1
which
Testing a solution of starch with a colorimeter
solutions
absorbance
or
Link
transmission).
graph
of
the
colorimeter
readings
against
the
concentration
of
You
can
read
more
about
using
a
starch.
colorimeter
7
Follow
8
The
exactly
the
same
procedure
with
any
test
to
an
intercept
on
of
the
starch
in
the
test
sample
the
sample.
concentration
concentration
determine
can
be
found
by
taking
on
page
of
starch
in
a
solution
52.
graph.
Summary questions
1
A
student
following
Fruit
juice
juices
Colour
after
orange-red
Q
green
R
blue
the
table
reducing
method
Explain
Make
a
with
Benedict’s
on
sugars
the
opposite
boiling
page
to
with
solution
Benedict’s
estimate
in
the
three fruit
juices.
of nding
out
the
concentration
why
the fruit
3
some fruit
P
Use
2
tested
with
the
results:
the
actual
Benedict’s
test
cannot
Explain
show
solution
the
concentration
the
limitations
in
any
whether
test
or
of
of
this
substance.
not fructose
is
in
juices.
table
to
show
how
to
make
the following
dilutions from
a
–3
100 g dm
starch
solution:
–3
50.0,
4
Explain
the
reducing
5
Draw
the
10.0,
difference
5.0,
1.0,
between
0.5,
0.
1,
0.05
qualitative
and
and
0.01 g dm
quantitative
.
tests for
sugars.
a ow
chart
decrease
in
to
show
the
concentration
procedure
of
starch
in
that
you
bananas
would
as
use
they
to
determine
ripen.
21
1.
11
Biochemistry
Y
our
Learning outcomes
summary
Unit
questions
On
completion
of
this
section,
be
able
recognise
questions
and
those
the
multiple-choice
that
test
that
understanding

list
the
short
and
this
section
with
different
answer
knowledge
based
on
to
There
also
knowledge
are
ways
in
questions
which
are
to
requires
levels
of
do
the
to
of
is
the
organisation
have
the
you
what
chapter
.
these
knowledge
on
the
In
and
CD
the
three
next
types
section
of
questions
understanding
that
relate
to
there
of
this
are
are
more
chapter
.
each
chapter
.
will
test
section
are
to
your
of
labelled
show
recall
the
subject
with
you
K
where
knowledge
areas
you
(knowledge)
they
apply.
and
have
your
ability
and
covered.
U
They
of
will
K
to
The
apply
MCQs
in
(understanding
NOT
be
labelled
of
like
in
the
examination.
answer
In
the
examination
you
put
your
answer
on
a
sheet.
Haemoglobin
is
an
example
of
a
protein
with:
A
primary
structure
B
primary
and
C
primary,
secondary
D
primary,
secondary,
to
is
(polypeptides)
of
only
secondary
structure
only
and
tertiary
structure
only
of
work
tertiary
and
quaternary
structure
(K)
question. A
haemoglobin
levels
right
your
questions
understanding
made
Which
so
organisation
it
of
the
following
shows
the
correct
bond
associated
with
each
of
of
the
globins
all four
test
this
know
2
four
show
in
longer
you
not
anything from
molecule
will
foc us
proteins. You
out
short-answer
answers.
of
MCQs
your
1
the
questions,
questions.
S tudy
about
longer
The
special
1
requiring
(MCQs)
this
Question
multiple-choice
Multiple-choice questions
this
answers
answer
we
topics
questions
knowledge)
plan
questions
of
test
written

consists
to:
like

test
you
In
should
1
biological
molecules
shown?
has
and
D
Disaccharide
Polysaccharide
Protein
Triglyceride
ester
glycosidic
covalent
peptide
peptide
ester
glycosidic
covalent
glycosidic
glycosidic
peptide
ester
glycosidic
peptide
ester
glycosidic
answer.
A
B
C
D
(K)
Question
2
that
the
hold
turn.
then
3
S tudy
at
Section
answer. This
is
these
in
1.4
an
multiple-choice
negative
to
check
example
question
statement.
the
exam,
Look
as
your
of
a
with
a
most
often
they
Starch
on
to
and
you
the
match
together
.
think
next.
glycogen
is
are
It
the
The
up
is
the
a
right
right
macromolecules
good
idea
answer
answer
polysaccharides.
is
to
for
read
the
and
each
rst
the
bonds
column
column
in
and
C
Which
one
of
the
following
feature
of
starch
but
not
of
is
glycogen?
A
Starch
is
B
Starch
has
C
Starch
contains
1,6
glycosidic
bonds
D
Starch
contains
1,4
glycosidic
bonds
made
an
from
a
glucose
unbranched
component
(U
are
each
case,
you
have
to
work
out
whether
the
statement
applies
difcult.
to
22
move
sub-units
what
to
out for
In
the
Circle
you
foc us
a
Look
requires
glycogen
or
not.
The
only
statement
that
does
not
apply
is
B
of
K)
Module
Short
answer questions
1
Cell
and
questions
variety
of
in
Paper
different
2
are
answered
in
a
different
way
and
involve
completing
Question
responses:
5
matching

completing

writing
pairs
(see
Question
sentences
one
word
1
on
(Question
answers
page
24)
terms
When
4)
table
(Question
For
writing
sentences
5b)
(Question
6a
and
giving
labels

describing
on
a
diagram
or
pattern
or
trend

interpreting
4
Copy
information
in
you
from
a
table
or
in
write
and
collagen
the
form
of
text,
table,
graph
using
the
or
diagram.
the
each
of
the
following
spaces
is
essential
for
life.
It
passage
by
most
is
the
main
makes
component
substances
of
dissolve
up
most
of
the
cytoplasm
in
…
bonds
that
form
that
the
…
between
the
a
tops
those
of
boundary
over
5
to
a
wide
State
Collagen
very
body
in
fluids,
water
between
molecules
between
range
what
and
tall
is
of
trees.
water
so
water
which
They
and
such
as
making
it
molecules
explains
meant
by
the
are
are
air
.
temperatures
haemoglobin
blood.
make
has
State
TWO
types
of
an
haemoglobin
bonds,
have
in
…
State
three
are
responsible
THREE
structure
ways
of
in
T
riglycerides
a
Explain
suitable
b
Explain
for
cell
and
how
for
polypeptide
triple
helix,
but
polypeptides.
questions
ask
between
why
water
two
responsible
W
ater
remains
it
a
as
term
also
has
primary
high
in
…
three
n
both
points
as
a
and
there
marks
is
for
able
the
the
…
available.
Describe
and
Refer
then
to
the
link
it
to
the
glossary for
to
…
technical
terms.
at
state
.
structure
of
a
S tudy
protein.
foc us
proteins.
other
than
peptide
bonds,
that
7
is
not
an
essay
question,
collagen
you
will
need
to
structure
your
common.
which
the
structure
of
collagen
differs
carefully,
deciding
on
a
from
to
answer
the
question. You
haemoglobin.
phospholipids
the
structure
energy
how
three
has four
least
structure
might
6
both
for
strategy
the
make
about
.
answer
c
the
storage
structure
of
are
in
triglycerides
than
of
found
animal
makes
carbohydrates,
phospholipids
and
plant
them
such
makes
cells.
glycogen.
them
a
table
compare
more
as
or
want
suitable
always
you
give
the
one
or
good
answer rst,
once
membranes.
a
if
to
question
more
idea
you
have
numbered
to
can
asks
items.
plan
cross
written
points
you
t
to
is
your
it
your
out
answer
in full.
Longer
Paper
total
7
2
of
answer question
also
15
has
some
longer
answer
questions
and
each
of
these
has
a
marks.
Carbohydrates
a
Describe
b
Explain
Proteins
and
the
why
proteins
structure
glucose
perform
many
is
are
of
biological
glucose
soluble
roles
and
in
inside
molecules.
sucrose.
water
,
cells;
but
starch
starch
is
an
is
not.
energy
storage
molecule.
c
i
Explain
of
ii
how
the
structure
of
a
protein
differs
from
the
structure
starch.
Explain
why
performs
a
Many
excellent
but
and
a
relationship
at
Question
b
about
proteins.
give
something
these
appropriate
travel
think
two
you
and function.
function.
the
the
b
cells
the
The
part
provided.
are
different
of
syllabus.
suitable
b
and
the
haemoglobin,
haemoglobin
structure
W
ater
is
graph
about
word(s)
it
denitions
drawing
Notice
complete
in
difference
chains forming
and
why
the
b)
e.g.
a
given
comparing
collagen

you
learn
answering
each
sure

shows
to
tables
the

foc us
a
important

biology
(SAQs)
S tudy
The
molecular
proteins
perform
multiple
roles,
but
starch
only
one.
23
1.
12
Practice
exam-style
questions:
Biochemistry
Try the following questions
1
Figure
1.
12.
1
shows
eight
as
examination
biological
practice.
B
A
CH
C
OH
CH
2
molecules. Study
them
OH
S tudy
2
carefully
O
H
OH
H
H
H
and
then
answer
the
questions
that
H
N
COOH
C
Before
2
OH
OH
H
OH
OH
follow.
you
H
answering
each
question,
biological
choose
molecules
and
one
of
OH
carefully
write down
D
CH
CH
OH
E
OH
it
relates
to. You
molecular
and
H
each
molecule for
more
and
there
may
be
more
at
all.
letters
that
you
do
not
them. Circle
amino
acid
that
is
a
of
OH
N
OH
OH
signicant
G
CH
H
N
C
collagen
that
identify
Put
question
3
OH
CH
CH
you
them.
CH
3

H
parts
H
H
help
major
any
COOH
C
2
use
2
constituent
CH
2
O
an
H
O
F
a
identify
HO
H
H
one
H
or
to
2
OH
question
try
CH
than
OH
one
the
structures
O
may
H
choose
at
2
O
letter
look
OH
H
the
2
the
start
H
OH
H
H
In
foc us
O
N
C
H
C
H
C
N
CH
H
C
H
CH
marks
by
the
side
of
3
those
3
you
don’t
2
O
b
disaccharide found
in
the
know. Try
O
H
that
is
polymerised
C
C
molecule
with
a
peptide
molecule
that
form fatty
f
molecule
an
amino
hydrolysed
C
C
O
O
H
O
O
C
O
H
C
O
C
O
C
O
O
to
acids
with
hydrophobic
g
is
H
C
H
bond
C
e
C
cellulose
O
d
O
H
H
H
H
form
H
to
hydrophilic
and
regions
acid
that forms
Figure 1.12.1
disulphide
2
A
student
The
bonds
tested
results
Tissues
of
in
some
the
proteins
plant
and
biochemical
Results of
animal
tests
are
tissues
shown
to find
in
the
out
which
biological
molecules
Benedict’s
Iodine
S tudy
solution
solution
Biuret
Ethanol
reagent
water
and
Look
red
B
precipitate
contained.
yellow-brown
lilac
white
blue
blue-black
blue
no
emulsion
C
green
blue-black
lilac
no
emulsion
D
yellow
yellow-brown
lilac
white
emulsion
E
blue
yellow-brown
blue
white
emulsion
foc us
carefully
down
write
A
they
table.
biochemical tests
the
across
columns
some
notes
of
to
the
the
help
rows
Use
the
i
contain
ii
did
iii
contain
b
State
c
What
not
the
biochemicals from
in
the
table
to
state
which
tissues:
starch
contain
lipids
which
your
any
and
tissues
conclusions
Explain
24
information
sugars
proteins.
are
can
answer.
reducing
likely
be
to
made
be
plant
about
in
the
origin
and
relative
explain
and
you
results.
a
and
table
emulsion
identify
precipitate
your
concentrations
answer.
of
reducing
read
questions rst.
H
molecule
to
O
the
phloem
c
P
not
sugars
in
the five
tissues?
the
Module
3
The
table

in

as
Copy
each
You
below
living
an
includes
statements
roles
of
and
molecular
biology
water:
complete
the
living
table
organisms.
by
indicating
with
a
tick
( )
which
one
of
the
properties
of
water
is
responsible for
role.
should
Roles of
put
only
one
tick
water
in
each
heat
transport
blood
medium
plasma
surface for
walk
row.
Properties of
High
to
the
Cell
organisms
environment for
and
about
1
and
small
water
specific
Strong
capacity
cohesive forces
between
water
High
molecules
heat of
Solvent for
vaporisation
molecules
polar
and
ions
in
phloem
insects
on
major
component
sweat
used
movement
in
of
of
heat
loss
water
in
xylem
prevents
body
4
A
wide variations
student
carried
Benedict’s
the
in
temperature
out
a
quantitative
solution. After
precipitate. The filter
the
test,
paper
Concentration of
test for
the
with
Initial
reducing
reaction
the
sugars
mixtures
precipitate
was
by
testing
were filtered,
dried
mass of filter
and
known
concentrations
using filter
then
paper
weighed. The
Mass of filter
paper
and
of
of
glucose
known
results
are
mass,
in
Difference
the
in
with
to
remove
table.
mass/g
–3
glucose/g dm
paper/g
precipitate
0
0.84
1.
16
0.32
20
0.83
1.
17
0.34
40
0.81
1.
17
0.36
60
0.82
1.27
0.45
80
0.84
1.24
0.40
100
0.83
1.27
0.44
a
State
which
b
Describe
result
the
is
an
anomaly.
precautions
that
the
student
should
S tudy
take
are
c
to
make
sure
that valid
and
reliable
to find
how
the
Approach
the
student’s
reducing
sugar
method
can
be
concentration
foc us
results
collected.
Suggest
after drying/g
used
of
question
a fruit
six
questions
has
six
logically, for
marks
allocated
example
you
if
should
part
b
write
of
at
this
least
precautions.
juice.
d
Explain
state
using
5
why
the
the
student
glucose
this
would
not
concentration
of
be
able
to
the fruit
juices
method.
a
Describe THREE
ways
in
b
Explain
why
the
energy
c
Explain
why
cellulose
is
which
polysaccharides
available
in
suitable for
glycogen
making
differ from
can
cell
be
made
walls
of
polypeptides.
available very
quickly.
plants.
25
1
Cell
2.
1
Introduction
and
molecular
Learning outcomes
Using
We
On
completion
of
this
section,
be
able
use
see
dene
the
light
microscope
microscopes
are
so
small.
in
biology
There
are
because
two
many
types
of
of
the
things
microscope
that
that
we
you
want
need
to
to:
know

a
cells
you
to
should
to
biology
terms
resolution
about:
and

light

electron
microscopes
magnification

describe
how
to
use
a
microscope

list
the
The
differences
animal
and
plant
principles
electrons
are
electrons
pass
a
light
cells
as
the
two
by
types
lenses
of
microscope
on
an
object
are
to
similar
.
be
viewed.
Light
The
or
light
through
or
are
absorbed
or
diffracted
by
the
object.
or
Further
seen
focus
the
light
or
beam
of
electrons
so
that
an
image
of
the
object
microscope.
can
a
be
eyepiece
viewed.
condenser
lenses
give
In
a
lens,
the
light
microscope
objective
lenses
microscope
the
such
and
an
ability
to
as
that
in
eyepiece
magnify
Figure
lens.
the
2.1.1,
The
object
there
is
objective
by
×4,
×10
objective
or
lens
lens
×40.
The
image
formed
by
these
lenses
is
magnified
by
the
eyepiece
(4)
lens,
which
power),
is
usually
×100
×10.
(medium
The
power)
overall
and
magnifications
×400
(high
are
×40
(low
power).
objective
objective
lens
of
focused
between
lenses
with
microscopes.
light
10)
(40)
No
matter
how
impossible
to
microscope
stage
to
clips
see
is
detail.
much
see
an
very
limited
The
object
fine
by
is
detail.
the
resolution
magnified
This
is
wavelength
of
your
eye
in
the
because
of
is
light.
light
the
microscope,
resolution
Resolution
about
0.2 mm
is
(200
of
the
it
is
the
ability
µm),
which
coarse
means
focus
that
any
objects
closer
together
than
this
are
seen
as
one
object
stage
not
two.
Y
ou
cannot
see
any
object
smaller
than
200
µm.
The
resolution
condenser
slide
fine
of
your
eye
is
a
function
of
the
density
of
light
receptor
cells
in
your
lens
focus
retina.
light
The
resolving
light
and
light
has
about
Figure 2.1.1
how
a
half
power
the
of
wavelength
the
a
light
size
microscope
is
is
interrupted
between
interrupt
dependent
by
400 nm
the
light
objects
and
rays
on
in
the
the
700 nm.
and
can
wavelength
specimen.
Objects
be
seen
in
of
Visible
which
the
are
light
A typical school or college
microscope.
Anything
that
is
smaller
than
200 nm
cannot
be
seen.
The
light microscope (the condenser lens is
light
microscope
has
a
resolution
of
200 nm
(0.0002 mm),
which
means
beneath the stage)
that
two
points
Anything
S tudy
the
foc us
in
–6
1 nm
=
1
×
10
3
mm;
there
are
10
nm
light
size
and
in
separated
smaller
,
such
microscope
are
resolved
as
are
and
photographs
by
this
cell
distance
membranes,
magnified
we
taken
can
can
then
see
through
seen
cannot
small
them
the
be
be
objects
directly
as
separate
seen.
larger
through
If
images
than
the
objects.
in
200 nm
eyepiece
eyepiece.
3
in
a
µm;
there
are
10
µm
in
a
mm.
Magnification
size
of
rules
S tudy
an
for
is
image,
the
ratio
such
calculating
as
a
between
drawing
magnifications
the
or
actual
a
and
size
of
photograph.
actual
an
size
of
image
____________
=
actual
When
calculating
actual
sizes
magnications
always
size
actual
drawings/diagrams
never
26
centimetres.
photographs
in
millimetres,
of
image
_____________
take
measurements from
size
and
or
size
=
magnification
and
Remember
sizes:
foc us
magnification
object
the
these
Module
Drawing
Y
ou
can
1
Cell
and
molecular
biology
cells
make
temporary
microscope
cell
preparations
Remove
as
a
leaf
Elodea.
stain
plant
from
Place
with
coverslip
of
on
a
on
iodine
top
and
a
animal
water
slide
solution.
and
dry
plant,
in
the
such
water
Put
middle
and
surfaces
of
the
top
slide.
and
Place
cytoplasm
of
each
nucleus
cytoplasm
slide
in
turn
microscope
on
the
and
stage
focus
of
with
nucleolus
the
the
low
You
power
objective
lens
(e.g.
×4).
When
change
to
the
medium
can
look
at
animal
cells
in
by
focus,
lamella
a
strand
bottom
wall
cells.
power
placing
tissue
on
some
a
crushed
slide,
liver
staining
with
cytoplasm
lens
and
then
the
high
power
lens.
methylene
with
Figure
two
2.1.2
types
shows
of
cell
drawings
made
of
under
a
blue
cover
and
covering
slip.
these
high
nucleus
power
.
Figure 2.1.2
When

you
make
make
the
a
high
drawing
power
fill
at
drawing
least
half
of
cells,
the
space
Drawings of a leaf cell of Elodea and a liver cell (magnification = × 1000)
follow
these
provided;
simple
leave
rules:
space
Link:
for
Look
labels
and
annotations
at
page
drawings,

use
a
sharp
pencil
(e.g.
HB)
and
never
use
a
use
clear
,
internal

make
show
know
cell
The
sure
that
e.g.
to
show
the
of
should
have
the
be
proportions
the
same
contents
present;
are
do
of
the
outline
same
of
as
width : length
cells
not
use
–
draw
any
the
cells
and
any
drawings
the
cells
you
on
asked
plan
to
of
and
high
make
cells from
power
the
same
slide.
are
ratio
what
shading
you
or
see
not
colouring
what
for
you
the
2.1.2
are
and
differences
summarised
in
between
this
the
plant
and
animal
cells
in
S tudy
Plant
Animal
cell
cell




membranes
Plant
Animal
resolved
cell
cell
They
chloroplast


large


Feature
in
are
visible
as
shape
vacuole
a
the

cytoplasm

approximate
40
–
the
label
you
too
small
put
what
they
‘cell
you
be
of
by
are
labels
on
not
membrane’
are
boundary
to
microscope.
indicated
although
if
outer
are
light
often
drawings
wall
foc us
table.
Cell
xed
advice
be
contents.
Feature
cell
may
drawings
microscope
the
you
details
similarities
Figure
lines
details
drawing,

continuous
you
pen
plan

35 for
(notes)
labelling
the
is
cell.
20
size/µm

nucleus

Summary questions
S tudy
1
Describe
how
to
make
a
temporary
slide
of
plant
tissue
and focus
it
with
In
the
high
power
of
a
Summary
Find out why
3
Explain
question
microscopists
use
phase
contrast
and uorescence
microscopy.
and
width
millimetres
and
magnication.
the
difference
between
the
terms
magnification
and
Calculate
answers
the
to
actual
the
sizes
nearest
of
the
cells
micrometre.
shown
in
Figure
of
the
measure
divide
cells
the
by
in
the
Remember
to
resolution.
multiply
4
4,
microscope.
length
2
foc us
2.
1.2. Give
your
by
1000
micrometres
to
the
and
nearest
to
give
round
whole
a
up
result
or
in
down
number.
27
2.2
Cells
–
electron
Learning outcomes
Cells
The
On
completion
of
this
section,
be
able
light
more detail
microscope
microscope
state
the
electron

explain
an
differences
and
the
electron
light
between
400
microscopes
advantages
of
microscope
in
using
times
range
that
of
resolution
and
identify
far
not
greater
show
the
details
resolution.
A
of
cells.
beam
of
For
this
electrons
we
has
need
a
organelles from
of
1.0 nm
taken
and
than
in
therefore
that
of
a
structures
the
electron
a
light
and
resolving
power
microscope.
even
large
of
This
0.5 nm
allows
molecules
in
which
us
to
see
microscope.
2.2.1
Figure
shows
animal
2.2.2
a
an
electron
drawing
micrograph
made
from
the
of
a
human
white
blood
cell
micrograph.
and
electron
micrographs
of
the
plant
and
animal
cells
were
made
with
plant
transmission
electron
microscope .
The
electron
beam
passes
through
cells
the
list
the
animal
differences
and
electron
plant
between
cells
as
seen
specimen
can
in
be
to
replaced
operator
can
hit
photographic
with
view
a
the
paper
fluorescent
image
and
to
screen
search
make
or
for
the
digial
image.
camera
suitable
The
so
features
paper
that
the
to
photograph.
micrographs.
nuclear
envelope
nucleolus
nuclear
pore
cytosol
cell
membrane
nucleus
Golgi
body
mitochondrion
rough
endoplasmic
reticulum
Figure 2.2.1
Electron micrograph of a
Figure 2.2.2
Made using Figure 2.2.1 showing the organelles in a white blood cell
white blood cell (× 6700)
(× 6700)
The
electron
beam
is
focused
by
magnetic
lenses
in
a
column
that
Link:
contains
column
An
electron
micrograph
of
a
is
on
page
the
so
that
the
the
Pumps
electron
specimen
30.
fluorescent
28
specimen.
are
beam
used
is
not
to
remove
deflected
the
on
air
its
from
the
pathway
plant
through
cell
a
photographs
electron
a

is
terms
The
micrographs
of
better
magnication
and

a
sub-cellular
are
Figure
of
with
to:
wavelength

does
you
a
should
in
microscopy
screen.
to
the
photographic
paper
,
digital
camera
or
Module
The
following
table
lists
the
differences
between
light
microscopy
1
Cell
and
foc us
microscopy.
Use
Feature
Light
microscope
Electron
the
internet
wavelength/nm
400–700
learn
1.0
resolution/nm
200
0.5
highest
×1000
×250 000
without
study

loss
are
of
advantages
(at
of
best:
using
1500)
both
(or
light
and
electron
electron
on
cells. Use
these
to
recognise the organelles
page
31.
more)
microscopes
to
cells.
Light
such
microscopes
as
division
The
can
movement
movement

detail
of
how to
listed
magnication
to nd
microscope
micrographs
There
biology
and
S tudy
electron
molecular
of
of
vacuum
of
be
used
cells,
and
which
in
in
and
means
see
living
nuclear
movement
observed
fixation
to
phagocytosis,
chromosomes
cells
specimens
processes
of
of
that
all
and
living
division
processes,
digestion,
(mitosis
and
meiosis),
cytoplasm.
electron
staining
cells
intracellular
microscopes
kills
water
them;
must
are
they
be
are
dead
as
the
observed
removed
as
part
in
of
a
the
preparation.

V
arious
cells
in
techniques,
light
required

Some
of
in
artefacts

Light

The
electron
the
combine
Images
of
the
and

All
in
when
the
in
Light
the
are
are
be
not
used
very
the
thin
to
the
in
produce
thick
buy
living
stains
to
metals
that
cause
specimens.
It
is
so
the
easy
to
miss
thin.
either
the
iodine,
natural
methylene
colours
blue
slides).
are
in
black
colour-enhanced
to
heavy
specimens,
(e.g.
prepared
view
and
beams.
structures
colour
,
stains
to
cells.
quite
thick
microscope
cheaper
cell
this
used
fixatives
are
(100–500 nm).
are
for
be
the
electron
living
see
sections
of
can
of
microscopy
distort
to
colours
use
deflect
penetrate
stains
are
to
in
used
electron
microscopes
may
microscope
the
contrast,
the
electron
and
cut
specialised
images
in
cutting
or
phase
without
cannot
be
light
specimen
many
can
beam
must
computers

that
microscopes
electron
structures
as
microscopy
used
proteins
objects
specimens

stains
with
–
such
microscopes
than
and
white;
images.
electron
microscopes,
S tudy
which

also
need
Eukaryotic
resolution
trained
ribosomes
of
light
technicians
are
only
to
operate
25–30 nm
and
across,
so
maintain
they
are
below
the
Make
sure
you
Electron
cells,
microscopes
such
as
include
a
column for
microscopes.
the features

foc us
them.
allow
ribosomes,
viewing
that
are
of
not
very
small
visible
in
structures
the
light
within
question
you
choose
in
Summary
4.
microscope.
Summary questions
1
Calculate
Figure
the
actual
length
of
the
cell
shown
4
in
2.2.
1.
Make
a
animal
section
2
Explain
the
microscope
and
3
List
of:
advantages
to
palisade
the
i
(see
the
view
white
page
cells,
mesophyll
organelles
the
using
such
the
as
cell;
in
ii
the
palisade
and
white
blood
5
cells
Suggest
an
show
on
the
cells
page
differences
shown
in
between
the gures
in
the
this
30.
investigation
microscope
the
to
plant
electron
cells.
visible
blood
30 for
of
table
and
electron
palisade
mesophyll
is
best;
ii
the
in
which:
light
i
the
electron
microscope
is
best.
micrographs
mesophyll
cell
cell).
29
2.3
Cells
and
Cells
Learning outcomes
On
completion
should

be
able
dene
the
of
this
organelles
section,
have

obtain

gain

produce
list
the

energy
of
and
functions
convert
it
to
carry
into
out:
usable
form
raw
materials
from
their
surroundings
to:
term
biological
molecules,
such
as
carbohydrates,
lipids,
proteins
organelle
organelles
animal
variety
you
and

a
in
plant
nucleic
acids
and

package

excrete

store
materials
so
they
can
be
exported
from
the
cell
cells
outline
the functions
of
waste
materials
the
and
retrieve
genetic
information.
organelles.
Y
ou
can
cells
in
S tudy
foc us
the
the
of
a
eukaryotic
cell
as
generated,
materials
in
information
gained,
exported,
which
energy
stored,
products
substances
the
moved
It
reproduce
is
also
raw
made
and
blood
would
destroy
bacteria
and
a factory
animal
that
table
your
cells
occur
that
with
opposite
diagrams.
to
through
rest
of
plant
the
are
cell
the
are
organelles.
compartments
different.
previous
For
The
because
example,
section
structures
the
the
that
labelled
functions
of
conditions
lysosomes
in
a
contain
the
the
in
enzymes
a
that
digest
whole
white
membrane-bound
all
the
biological
cell.
blood
Lysosomes
cell
takes
structure
molecules.
are
up
otherwise
required
into
to
break
they
down
the
vacuoles.
and
the
the
organelles
that
you
need
to
know
about.
=
clearly
visible
in
school/college
light
microscope.
that
S
stands
structures
spun
in
a
for
and
membranes

protein
unit
which
macromolecules.
It
is
used
refers
to
to
measure
how
they
small
sediment
centrifuge.
structures

Svedberg
–
are
made
examples
are
of
mitochondria
and
chloroplasts
and
as
the
annotate
adding
cells
all
fibres
–
examples
are
centrioles.
organelles
cells. Use
Keep
about
the
of
label
information
animal
these
require
kept
shows
Sub-cellular
all
these
the
into
in
sub-cellular
can
foc us
in
be
that
table
Note
diagrams
in
The
waste
when
large
cell
must
cellular
Make
processes
micrographs
and
about
itself.
S tudy
and
localised
These
*
removed.
cell
electron
compartments.
is
The
components
are
the
into
a
white
complex factory
from
divided
plant
cell
that
Think
see
are
The
hair-like
flagella
surface
(singular:
structures
flagellum)
are
known
also
as
made
cilia
of
(singular:
protein
cilium)
and
fibres.
more
you
work
book.
Figure 2.3.1
Electron micrograph of a palisade mesophyll cell from a leaf. You can see
five chloroplasts, a nucleus and a large central vacuole. Between the chloroplasts are two
mitochondria that are smaller and paler. (× 3500)
30
Module
Organelle
Features
rough
at
endoplasmic
reticulum
(RER)
sacs
smooth
endoplasmic
reticulum
Golgi
like
(SER)
body
Function(s)
of
membrane
enclosing uid lled
ribosomes
space
RER
outer
surface
RER
but
is
covered
with
no
in
pile
of at
sacs
with
the
mitochondria
formed
(singular:
lled
matrix
mitochondrion)
inner
ribosomes
on
outer
makes triglycerides
membrane
vesicles forming
around
modies
edge
surface
of
single
two
membranes
area for
protein
and
secretory
attached
lysosomes
to
and
is
surrounding
highly folded
enzymes for
RER
or free
RNA
in
(30 nm
membrane
to
give
site
of
synthesis;
to Golgi
(fats),
*chloroplasts
many
(plant
area for
body
phospholipids,
–
diameter;
membranes
other
proteins;
makes
lysosomes
respiration
made
of
assemble
giving
large
pigments
amino
acids
to
make
proteins
80S)
surrounds uid lled
chlorophyll,
and
large
with
contain
out
internal
packages
vesicles
aerobic
enzymes for
parts
particles
only)
protein
respiration
cytoplasm
in
a uid
enzymes
cells
out
proteins
cholesterol
apparatus)
ribosomes
carry
transports
ribosomes
surface
(or Golgi
1
surface
site
and
of
of
cells
and
all
the
destroying
and for
worn
digesting food
bacteria
reactions
of
photosynthesis
enzymes
cell
membrane
surface
(or
cell
bilayer
membrane)
(see
of
page
phospholipid
with
proteins
cell
36 for features)
boundary;
controls
retains
exchange
of
cell
contents;
substances
with
surroundings
nuclear
envelope
structure
outer
pass
*nucleus
like
that
surface;
between
clearly
visible
of
pores
ER
to
with
allow
cytoplasm
in
LM
and
and
EM
ribosomes
on
substances
separates
to
allows
darkly
centrioles
(animal
made
cells
only)
the
staining
of
base
area
in
when
stained
contains
nucleus
protein bres,
of
a
cytoplasm;
between
the
two
nucleus
DNA
*nucleolus
nucleus from
movement
structure
in
store
produces
is
similar
to
assemble
cilium/agellum
of
genetic
information
as
chromosomes
ribosomes
the
spindle
chromosomes
when
to
move
nuclei
divide
Summary questions
1
Make
a
poster
organelles,
You
may
large
you
2
wish
work
your
the
synthesis
energy
of
to
table. You
Name
ii
that
includes
their functions
make
can
way
export
that
of
by
poster
white
the
are
iii
blood
of
each
within
in
to
of
the
the form
this
the
3
cell.
of
a
poster
involved
the
i
as
in;
i
the
cell;
and
digestion
the following
other
mitochondria
body;
4
how
each
iii
nuclear
the
intake
Describe
from
course.
proteins from
transformations;
materials
roles
information
through
organelles
and
the
add
drawings
and
Make
a
Name
in
and
smooth
pairs
structure
chloroplasts;
and
rough
of
organelles
differ
and function:
ER;
ii
iv
nucleus
cell
and Golgi
membrane
and
envelope.
list
the
functions
of
the functions
organelles
that
you
that
have
that
are
occur
involved
in
in
cells.
each
of
the
listed.
cells.
31
2.4
Eukaryotes
and
The
Learning outcomes
cells
because
On
completion
should
be
able
of
this
section,
the
to:
of

identify
eukaryotic
cell
cell
cells
in
they
into
the
electron
microscopes
describe
the
light
a
the
nucleus,
cells
have
organelles.
This
much
state
the
pages
which
is
complex
Organisms
2.4.1
has
all
structure
of
shows
these
a
are
the
eukaryotic
meaning
membrane
such
simpler
diagram
or
features
as
cell
of
cells.
the
structure
do
is
is
term
systems
bacteria
This
that
not
called
subdivide
have
this
sort
prokaryotic.
–
of
for
the
features
example,
seen
plenty
of
in
prokaryotes.
bacteria
do
No
one
have
flagella.
cell
cell
differences
not
a
loop

previous
and
capsules
prokaryotic
in
and
cell

have
These
structure.
Figure
prokaryotic
described
eukaryote.
you
prokaryotes
of
wall
DNA
between
capsule
prokaryotic

outline
the
and
eukaryotic
cytoplasm
cells
endosymbiotic
development
of
eukaryotic
cells.
storage
cell
granule
membrane
Link
ribosome
Look
at
the
diagram
and
the
table
to
flagellum
see
how
prokaryotic
the functions
Section
pages
2.3,
30
to
you
cells
carry
identied
Summary
out
Figure 2.4.1
in
question
4,
The features of prokaryotic cells
on
31.
Structure
Features
capsule
thick,
Functions
compact,
slimy
layer
outside
cell
wall
provides
protection for
bacteria,
reduces
cell
wall
made from
murein,
polysaccharide
cell
(surface)
phospholipid
not
cross
bilayer
cellulose;
linked
with
into
murein
mesh
proteins;
by
no
is
a
cholesterol
ribosome
contains
ribosomes,
contains
bacterial
smaller
(note
storage
granules
partially
than
of
granules,
enzymes;
have
glycogen,
20 nm
no
lipids
diameter;
70 S
(singular
made
of
one bre
and
protein
phosphate
store
enclosed
by
membrane
agellum)
genetic
material
of
smaller
chromosome
DNA
(prokaryotes
32
base
loops;
have
is
both
no
to
when
in
potential
allow
entry
and
protein
synthesis,
other
reactions
synthesis
energy
loop
are
of
in
nuclear
DNA;
the
plasmids
cytoplasm
envelope)
are
stores
copy
and
to
give
bacterium
of
of
haploid
lipids for
synthesis
rotates
moves
bacterial
bursting
water
ER)
and
not
dehydrating
permeable
membrane
agella
higher
parasitic
phagocytes
substances
chemical
in
of
respiration,
chromosome
eukaryotic:
prokaryotes
stores
storage
of
of
cells from
solutions
exit
against
chances
prevents
peptides
membrane
cytoplasm
e.g.
genetic
each
(see
corkscrew
through
information;
gene,
page
so
80)
motion;
liquids
one
prokaryotes
are
Module
The
differences
between
prokaryotic
and
eukaryotic
cells
are
listed
in
1
Cell
and
molecular
biology
this
table.
Feature
Prokaryotic
cell
Eukaryotic
Plant
typical
size/µm
0.5–3.0
capsule
found
cell

wall
membrane-bound
in
some
(murein,
not
cellulose)
ribosomes
smaller:
nucleus

DNA
bacterial
loop
of
20 nm/70 S
chromosome
DNA
in
is
a
cells
Animal
40–60
20




organelles
cells
(made
of

cellulose)


30 nm/80 S
30 nm/80 S


chromosomes
cytoplasm
cells
nuclear
made
of
linear
DNA found
within
envelope
Endosymbiosis
Endosymbiosis
is
the
idea
that
organelles
have
evolved
from
prokaryotes.
S tudy
Mitochondria
They
both
and
chloroplasts
share
many
features
with
have:
Symbiosis

a
loop
foc us
prokaryotes.
of
DNA
although
some
mitochondria

small

transfer
70 S
which
genes
are
in
is
similar
that
to
control
the
bacterial
features
chromosomes
in
the
in
interact
chromosome,
chloroplasts
gain
and
means
with
benet from
endosymbiosis,
nucleus
cells
ribosomes
that
each
in
a
the
cells
mutual
molecules
that
only
function
within
the
organelles
coded
for
by
genes
in
the
mitochondrial
and
chloroplast
similarities
bacteria
as
suggest
shown
in
that
Figure
these
organelles
have
been
live
inside
In
other
to
led,
so
prokaryotes
it
is
evolving
DNA.
into
The
both
association.
and
thought,
are
species
and
benecial
arrangement. This
RNA
two
other
derived
mitochondria
and
chloroplasts.
from
2.4.2.
loop
of
DNA
Summary questions
nucleus
anaerobic
prokaryotic
ancestral
cell
cell
of
1
photosynthetic
eukaryotes
–
the
terms
eukaryote
and
prokaryote.
algae
aerobic
2
and
Dene
List
the
structures found
in:
plants
prokaryote
i
both
prokaryotic
eukaryotic
aerobic
cells;
prokaryotic
photosynthetic
ii
cells;
cells
only
iii
and
in
only
in
prokaryotes
prokaryotes
eukaryotic
cells.
Dene
term
‘invade’
‘invade’
anaerobic
cell
3
cell
and
ancestral
aerobic
prokaryotes
cell
into
supports
eukaryotes
that
the
idea.
–
protists, fungi
Find
out
about
Lyn
Margulis,
and
of
the
early
champions
of
animals
the
Figure 2.4.2
endosymbiosis
evidence
non-photosynthetic
one
mitochondria
the
of
4
develop
the
outline
idea
that
organelles,
such
as
Endosymbiosis
mitochondria
evolved
by
and
chloroplasts,
endosymbiosis.
33
2.5
Tissues
and
organs
Some
Learning outcomes
eukaryotic
There
On
completion
should
be
able
of
this
section,
you
dene
the
terms
tissue
and
list
the
differences
tissues,
organs
between
and
the
with
they
are
different
body
a
are
unicellular
species
processes
nucleus.
described
of
of
Many
as
a
these
consisting
and
protist
eukaryotes
multicellular
.
they
occur
are
single
cells.
classified
within
have
Cells
of
bodies
specialise
one
as
mass
divided
in
of
into
different
organ
functions

many
All
cytoplasm
to:
cells,

are
protists.
organisms
cells,
organ
Groups
and
of
examples
are
similar
of
organised
cells
epithelial
are
cells
together
known
that
as
to
give
sheets
tissues.
forms
The
sheets
of
or
masses
table
of
cells.
includes
some
cells.
systems

list
the
and

major
organs
in
plants
animals
make
a
section
plan
of
a
drawing
plant
of
a
Type of
Single or
Surface
Example of
epithelial
Shape
multi-
features
location
cell
layered
squamous
single
none
alveoli
cross
organ.
in
the
lungs
multi-
S tudy
none
epidermis
layered
The
outer
layer
of
the
skin
is
Epithelia
line
the
the
single
microvilli
of
organs,
such
as
thin
the
oviduct
and
kidney
tubules
the
extensions
intestine,
lining
–
inner
short,
surfaces
skin
an
cuboidal
epithelium.
in
foc us
of
the
cell
membrane
trachea.
to
increase
surface
columnar
single
area
microvilli
lining
small
intestine
single
cilia
lining
and
lining
Tissues
are
groups
Organs
are
structures
several
The
major
table
of
similar
composed
functions
shows
you
cells
for
the
examples
that
of
carry
different
out
the
tissues
same
that
oviduct
function.
carry
out
one
or
body.
of
plant
and
animal
tissues
and
organs.
Plant tissues
Plant organs
Animal tissues
Animal organs
epidermis
leaf
epithelium
brain,
chlorenchyma
stem
muscle
tongue,
sclerenchyma
root
blood
spinal
eye
individual
parenchyma
trachea
bronchus,
cord,
and
ear
muscles,
bone
e.g.
xylem
cartilage
phloem
adipose
biceps
individual
bones,
e.g. femur
liver,
pancreas,
stomach,
large
intestine,
ovary,
34
small
testes,
and
kidney,
uterus
Module
In
animals,
organ
systems
comprise
of
several
organs
that
work
1
Cell
and
bring
about
sensory,
one
major
muscular
,
function
reproductive,
of
the
body.
digestive
and
The
excretory,
endocrine
of
organ
systems
in
systems
are
the
will
have
to
distribution
through
from
the
the
make
of
root
plan
tissues.
of
making
plan
drawings
of
mammals.
images
Y
ou
foc us
nervous,
Practise
examples
biology
together
S tudy
to
molecular
drawings
Figure
R anunculus .
of
sections
2.5.1
shows
Figure
2.5.2
a
through
organs
transverse
shows
a
to
show
section
plan
stems
of
cross
and
sections
leaves
that
of
you
roots,
can
download.
drawing
made
section.
b
air
space
xylem
a
epidermis
cortex
(parenchyma
tissue)
endodermis
phloem
Figure 2.5.2
A plan drawing made from the section of the root of
Ranunculus
Figure 2.5.1
a
Transverse section of a root of
Ranunculus with b
an enlarged view of the transport
tissue (xylem and phloem)
Follow

this
make
guidance
the
around
drawing
the

use
a

use
thin,
when
fill
drawing
sharp
pencil
making
at
for
(e.g.
least
half
labels
HB)
plan
and
and
drawings:
the
space
provided;
leave
space
Link
annotations
never
use
a
pen
TS
the
single,
boundaries
continuous
of
the
lines
to
show
the
outline
of
the
organ
and
is
make
same

do
the
as
not
proportions
in
the
abbreviation for
(also
called
a
transverse
cross
section)
tissues
and

the
section
of
the
tissues
in
the
plan
drawing
exactly
the
LS
is
the
longitudinal
abbreviation for
section.
section
include
drawings
of
cells
and
do
not
shade
or
use
any
colours.
Summary questions
1
Dene
2
List
3
the
organs
that
terms:
tissue,
comprise
reproductive
system, female
Find
list
out
blood,
4
the following
Find
leaf,
and
and
skeletal,
out
and
stem,
organ
and
the following
reproductive
the functions
organ system
organ
systems
system,
in
digestive
of
the following
animal
of
the following
plant
humans:
and
tissues:
male
nervous.
muscle,
epithelial.
list
root,
the functions
xylem,
phloem,
parenchyma,
organs
and
chlorenchyma,
tissues:
sclerenchyma
epidermis.
5
State
6
Suggest
the
purpose
some
of
making
advantages
of
plan
drawings
being
of
sections
multicellular
rather
of
organs.
than
unicellular.
35
2.6
Cell
membranes
Eukaryotic
Learning outcomes
the
On
completion
should

list
be
able
the
of
this
section,
contents
inside
you
cells
the
of
cell
components
of
cell
main
The
arrangement
proteins
the
arrangement
components

explain
state
why
in
a
cell
floating
external
the
surroundings.
organelles
that
They
described
provide
also
on
a
form
page
barrier
between
compartments
31.
of
in
of
membranes
these
a
sea
interior
and
molecules
of
lipid.
are
is
phospholipids
known
as
Phospholipids
hydrophilic
surfaces
a
and
fluid
form
facing
a
proteins.
mosaic
bilayer
the
with
with
cytoplasm
a
the
inside
surroundings.
Some
protein
molecules
are
associated
and
with
or
outside
of
the
membrane,
but
transmembrane
proteins
pass
are
the
membrane
forming
pores
and
channels.
mosaic
describe
2.6.1
gives
the
false
impression
that
the
components
of
a
the functions
membrane
of
membranes
membrane
membranes
as uid
and
its
the
components
the
Figure

and
are
of
of
through
known
cell
that
The
hydrophobic
describe
a
composed
to:
membranes

are
components
of
are
fixed
in
position
and
do
not
move
about.
In
fact,
the
cell
phospholipids
are
in
constant
motion
moving
about
within
each
membranes.
monolayer
,
which
phospholipid
generally
two
S tudy
2.6.
1
may
you
shows
can
have
why
remain
is
the
membrane
‘flip’
from
within
different
one
their
in
is
described
monolayer
monolayer
order
to
face
to
and
the
as
fluid.
the
the
Some
other
,
but
composition
different
of
the
environments.
foc us
a
simple
diagram
rarely
to
copy
draw
and
it
in
move
able
surface.
that
they
monolayers
Proteins
Figure
is
molecules
to
For
about
move
within
over
example,
the
the
lipid.
whole
carrier
The
surface
proteins
for
proteins
of
the
glucose
of
cell,
and
epithelial
but
cells
remain
sodium
on
are
one
are
learn. You
Paper
restricted
to
the
intestine.
They
microvilli
on
the
surface
of
epithelia
of
the
in
the
small
2.
are
not
found
on
the
side
epithelial
cells
that
faces
capillaries.
Link
Follow
the
advice
about nding
animations
of
membranes
given
other
cell
on
page
diagrams
v
and
surface
the
Component of
on
internet.
cell
membrane
Function
phospholipids
proteins
glycoproteins
chains
of
–
proteins
sugars
with
attached
on
short

form

uid,

permeable

impermeable

transmembrane

receptors for
exterior
side
cells

a
bilayer that
so
proteins
and
to
as
ions
hormones,
nerve
barrier
between
exterior of
cells
and
cytoplasm
about
molecules
and
proteins
sites for
a
move
non-polar
to
between
recognition
acts
can
large
are
polar
molecules
channels
and
carriers
neurotransmitters
cells
other
and
similar
muscle
cells
at
synapses
between
nerve
cells
when forming
tissues
during
development
glycolipids
sugars
–
lipids
attached
cholesterol
with
on
one
exterior
chain
of

recognition

stabilises
sites for
the
non-polar

and
lymphocytes
phospholipid
bilayer
by
binding
to
polar
‘heads’
and
‘tails’
controls uidity
temperatures
36
antibodies
side
by
and
preventing
becoming
phospholipids
too uid
at
high
solidifying
at
low
temperatures
Module
1
Cell
and
Figure 2.6.1
carrier
channel
molecular
biology
A diagram showing the fluid
protein
protein
glycolipid
glycoprotein
mosaic structure of a cell surface
membrane
cholesterol
phospholipid
7–10 nm
bilayer
Functions of
At
cell
membranes
surfaces:
S tudy
Function
Comments
barrier

many
water-soluble
across;
cell,
permeability

large
such
partially
some
permeable
and
proteins;
through

cell
many
movement
by
bulk

substances
or
ow
extended
area for
that
the
larger
cell
through
in
the
small
as
phospholipid
cannot
into
pass
diagram
intestine.
surface.
you
would
Use
preceding
to
of
an
epithelial
one
2.5
transmembrane
pass
proteins
See
required
leave
a
columnar
Draw
Draw
expect
help
LS
through
cell from
in
microvilli
the
on
organelles
to nd
Sections
a
the
in
2.2,
this
2.3
cell.
and
you.
through
microvilli to
absorption through
membrane
vacuoles.
are
Make
pass
and transmembrane
cannot
transmembrane
from
pass
through
bilayer
cannot
semi-permeable)
substances
surface
phospholipid
that
cannot
( not
can
others
membranes
increase
membrane
molecules
proteins,
substances
bilayer
absorption
as
substances
foc us
in
through
are
the
carried
small
endocytosis
proteins
vesicles
and
bilayer
to
or
or
exocytosis
Summary questions
on
page
39
1
recognition

receptors
have
binding
sites for
Dene
the following
terms:
cell
cell-signalling
surface membrane; fluid mosaic;
molecules,
such
as
hormones
and
growth factors
phospholipid bilayer; cholesterol;
glycoprotein; glycolipid;
Within
cells:
transmembrane protein
Function
Comments
form

2
Describe
the
membranes
compartments
isolation
of
hydrolytic
enzymes
in
lysosomes
do
not
harm
the
in
a
of
eukaryotic
cell.
so
3
they
distribution
State
the
width
of
a
cell
cell
membrane.

concentration
their

substances,
e.g.
enzymes
and
substrates
provision
of
of
of
4
areas
chloroplast
with
and
different
mitochondria
pH,
e.g.
have
interiors
visible
rest
of
Suggest
in
large
surface

chloroplasts
in
the
why
and
mitochondria
have
visible
electron
not
microscope.
membranes
are
as
two
parallel
micrographs
of
lines
cells
membranes
magnied

chloroplasts
molecules,
have
such
membranes for
as
by
100 000.
many
pigment
6
Find
vacuoles
surface
body
and vesicles
membrane
and Golgi
summarise
the uid
cell

and
the
evidence
chlorophyll
for
transport
light
are
for forming ATP
area
intracellular
membranes
cytoplasm
often
provide
why
different
5
pH from
Explain
move
into the
body to
cell
substances from
cell, from
surface
mosaic
structure
of
membranes.
cell
RER to Golgi
membrane
7
Explain
have
why
plant
cells
do
not
microvilli.
37
2.7
Movement
across
Cell
Learning outcomes
to
On
completion
should
be
able
of
this
section,
you
–
membranes
move
they
may
to:
in
are
be
list
the
move
ways
across
in
which
dene
and
Some
membranes
describe
active
exocytosis,

dene
the
out
of
raw
and
outside
barriers
cells.
to
Substances
materials.
cell
the
movement,
W
aste
products
leave
but
enter
they
because
substances
to
be
also
used
allow
cells
move
need
out
elsewhere
substances
them
because
or
they
because
they
cell.
substances
too
big
and
are
small
must
be
enough
enclosed
to
pass
within
a
through
the
membrane
membrane,
in
vacuoles
some
or
vesicles.
simple
diffusion, facilitated
osmosis,
are
substances
are

and
their
toxic
function

membranes
diffusion,
Movement
is
either
passive
or
active.
by
diffusion
transport,
Passive
endocytosis
term
water potential.
movement
Molecules
The
cell
energy
cross
does
comes
Metabolic
example,
blood
from

on
a
to
the
may
use
its
kinetic
be
of
energy
used
to
oxygen
gradient
own
of
create
from
the
the
the
maintained
down
energy
air
by
their
to
concentration
move
the
gradient.
molecules.
The
molecules.
gradient
in
in
alveoli
breathing
the
in
and
first
the
the
place
lungs
flow
–
into
of
for
the
blood
heart.
diffusion.
soluble
Molecules
substances
Oxygen

from
energy
Simple
are
need
movement
relies
the
membranes
not
and
small
carbon
and
Facilitated
such
as
pass
through
ethanol
dioxide
are
pass
small
the
phospholipid
readily
enough
through
to
pass
bilayer
.
the
Fat
bilayer
.
through
as
both
uncharged.
diffusion.
Polar
molecules
cannot
pass
through
the
Did you know?
phospholipid
open
Aquaporins
are
special
all
the
with
a
polar
lining
to
to
diffuse
in
or
to
there
allow
are
channel
movement
proteins
down
a
for
them.
gradient.
These
are
Carrier
out
of
also
allow
movement,
but
these
open
when
molecules
bind
allow
to
water
time
so
channel
proteins
proteins
bilayer
them,
they
are
not
open
all
the
time.
W
ater
molecules
are
polar
and
cells.
they

cannot
Osmosis.
of
water
higher
easily
This
is
through
water
pass
a
a
special
type
partially
potential
high
through
to
a
the
of
bilayer
diffusion
permeable
place
with
(see
that
page
involves
membrane
a
lower
36).
from
water
the
a
movement
place
with
a
potential.
concentrations
low
concentration
carrier
S tudy
carrier
foc us
protein
protein
This
diagram
shows
concentrations
either
side
of
of
the
the
different
substances
on
membrane.
channel
protein
simple
diffusion
Figure 2.7.1
Water
facilitated
diffusion
active transport
This diagram shows the different ways in which molecules cross membranes
potential
Link
W
ater
Osmosis
and
water
potential
potential
another
focused
page
upon
in
more
detail
is
the
tendency
of
water
to
move
from
one
are
and
is
determined
by:
on

the
quantity
of
water

the
concentration
present
40.
38
of
solutes,
such
as
ions
and
sugars
place
to
Module

the
pressure
exerted
by
the
cell
wall
(in
plant
cells
and
1
Cell
and
in
animal
Solutions
with
molecules.
of
solute
high
water
Solutions
with
potentials
have
low
potentials
water
low
concentrations
have
high
of
Channel
solute
concentrations
molecules.
moves
and
from
proteins
a
solution
with
a
high
water
potential
to
a
a
low
water
potential.
Cells
contain
cytoplasm
and
carrier
transmembrane
are
proteins
are
proteins. Channel
used
carrier
in facilitated
proteins
in
solution
facilitated
with
foc us
cells).
diffusion;
W
ater
biology
prokaryotes,
S tudy
not
molecular
plant
cells
diffusion
and
active
also
transport.
contain
such
as
cell
potential
always
into
cell
travel
water
forth
of
than
the
water
sea
and
sea
out.
tap
of
water
.
is
cell
no
a
into
net
are
cell
movement
in
movement
is
about
solutes,
lower
water
molecules
cells
the
movement
contents
many
much
W
ater
When
net
the
contain
have
move
The
water
,
there
potential
cells
membranes.
move
same:
or
molecules
into
These
thus
water
across
water
placed
about
The
vacuoles.
ions,
distilled
more
gradient
potential
Active
and
large
and
with
When
usually
molecules.

back
cell.
their
sugars
water
,
potential
the
is
inside
compared
distilled
water
into
sap
proteins,
placed
down
of
water
and
of
S tudy
foc us
the
out
is
of
Vesicles
the
term
or
vacuoles? Vesicle
used to describe
is
a
small vacuoles.
water
the
same
as
the
water
.
movement
Active
transport.
present
in
cells
diffusion.
by
very
Some
substances
Cells
have
these
they
to
other
,
then
soil
in
against
proteins
them.
to
They
their
accept
the
to
will
out!
in
not
T
o
that
root
on
from
cells
one
so
into
these
gradients.
to
one
that
glucose
are
move
gain
respiration
molecules
absorb
cells
concentration
by
molecules
happens
kidneys
inside
move
released
move
This
the
tend
energy
to
required
outside.
will
moved
shape
and
they
own
Carrier
release
water
be
their
change
are
concentrations
Instead
must
use
substances.
membrane,
from
low
substances
move
side
side
of
to
absorb
it
is
the
the
ions
not
lost
in
urine.

Bulk
transport.
endocytosis.
Cells
For
take
example,
in
particles
from
phagocytic
their
while
surroundings
blood
cells
take
by
in
bacteria.
Summary questions
These
or
are
much
through
the
membrane.
too
bilayer
This
Lymphocytes
large
so
pass
are
reduces
produce
to
through
enclosed
the
in
quantity
antibodies
that
the
a
of
transmembrane
vacuole
made
membrane
are
large
at
of
the
molecules.
proteins
cell
cell
surface
1
surface.
These
Dene
the following
diffusion,
terms:
simple diffusion,
are
facilitated diffusion, vesicle,
enclosed
within
vesicles
made
by
the
Golgi
body
and
move
to
the
cell
vacuole, active transport,
surface
membrane.
They
fuse
with
the
membrane
so
that
their
exocytosis, endocytosis, secretion.
contents
are
membrane
vesicles
expelled
becomes
and
to
the
part
vacuoles
of
outside
the
requires
cell
by
exocytosis.
surface
energy
from
The
membrane.
the
vesicle
Movement
2
of
cell.
3
Exocytosis
Explain
why
in
Explain
there
why
to
cell
of
vesicle
and
out
are
cross
of
cells.
special
Endocytosis
channel
contents
substances
membranes
food
released
to
surroundings
particles
cell
surface
proteins
(aquaporins) for
‘stick’
water.
membrane
vesicle fuses
4
with
cell
the
differences
between
surface
the following
membrane
to
vesicle
Explain
cell
surface
pairs:
i
channel
infolds
surround
protein
particles
and
carrier
protein;
ii
moves
simple
towards
and facilitated
diffusion;
cell
vacuole
moves
iii
surface
through
passive
and
active
transport
cytoplasm
membrane
and
may fuse
with
across
a
membranes;
iv
secretion
lysosome
and
protein
molecules
packaged
are
excretion; v
exocytosis
and
endocytosis.
into
Golgi
body
modifies
and
packages
proteins
lysosome
releases
vesicle
for
export from
the
cell
by
exocytosis
or
enzymes
for
digesting
particles
taken
in
by
into
vacuole
5
Find
to
digest food
of
endocytosis
particles
and
Figure 2.7.2
examples
endocytosis
exocytosis
and
list
them.
Bulk transport across membranes – exocytosis and endocytosis
39
2.8
Investigating
Learning outcomes
water
Salty
solutions
During
On
completion
should

be
able
dene
the
of
this
section,
potential
your
course
you
should
develop
your
skills
of
experimental
you
design,
data
presentation
section
deals
and
data
analysis
and
interpretation.
This
to:
terms
water potential
immersing
with
these
tissues
in
skills
in
solutions
the
of
context
different
of
investigating
water
the
effect
of
potential.
gradient, plasmolysis, turgid,
Read
through
the
four
investigations
described
in
this
section
and
answer
flaccid
the

explain
that
type
diffusion
osmosis
is
a
questions

describe
and
explain
the
immersing
plant
and
in
solutions
of
more
questions
on
this
topic
in
1
animal
the
fruit
of
an
egg
plant,
Solanum
melongena ,
into
equal-sized
different
sections.
water
are
effects
Cut
tissues
There
2.10.
Investigation
of
follow.
special
Section
of
that
Place
the
sections
into
five
different
concentrations
of
salt
potential.
(sodium
chloride).
Concentration of
The
results
sodium
are
summarised
here:
Observations on the
egg
plant tissue
–3
chloride/mol dm
compared
0.00
rmer
(distilled
water)
0.25
very
0.50
slightly
0.75
softer
1.00
very
with freshly
cut tissue
similar
softer
–3
Figure 2.8.1
than
in
0.50 mol dm
soft
Sections cut from egg plants
make good material to investigate osmosis
and plant cells. The changes happen very
quickly.
Investigation
Add
one
observe
S tudy
foc us
sample
red
The
are
results
in
Investigations
descriptive
or
1
and
drop
the
and
blood
of
2
fresh
place
on
a
of
to
the
different
contents
microscope
slide
concentrations
of
the
and
of
test-tubes.
observe
the
salt.
Stir
Remove
and
a
appearance
of
the
cells.
2
qualitative. Try
Concentration of
Summary
blood
appearance
question
2
on
page
43
sodium
Observations of the
blood
–3
chloride/mol dm
using
your
plant
and
knowledge
animal
S tudy
Do
not
refer
solutions.
actual
given
It
in
a
and
0.00
(distilled
water)
to
is
a
present,
cells
red
present,
solution
few
0.
15
cells
‘weak’
best
to
low
or
or
and
0.25
shrunken
cells
present,
no
red
solution
0.50
shrunken
cells
present,
no
red
solution
present,
no
red
red
solution
solution
refer
if
to
‘strong’
to
they
say
their
are
that
a
high
of
the
3
solute
This
is
tissue.
40
cells
0.06
Investigation
concentration
concerned.
no
foc us
question
has
osmosis
cells.
concentrations
solution
of
an
investigation
to
obtain
some
quantitative
results
using
plant
Module
Choose
a
suitable
plant
tissue
such
as
the
storage
tissue
from
tubers
1
Cell
and
or
yam,
potato,
Solanum
Dioscorea
alata .
tuberosum ;
The
part
of
sweet
these
potato,
plants
Ipomoea
that
you
eat
biology
of:
S tudy
European
molecular
foc us
babatas ;
is
storage
These
are
the
variables
in
this
tissue.
investigation:

Use
a
cork
cylinders
borer
or
or
a
chip
machine
to
cut
the
storage
tissue
into

independent
sucrose

T
rim
same

the
–
concentration
of
‘chips’.
ends
so
they
are
squared
off
and
make
the
pieces
all
solution
the

dependent

derived
–
change
in
mass
length.
Weigh
the
pieces
and
record
their
individual
–
percentage
change
in
masses.
mass

Place
the
pieces
into
separate
test-tubes
each
containing
solutions
of

sucrose
as
shown
in
the
results
table
control
–
type
immersion,

After
12
hours
reweigh
the
pieces
and
record
the
this
mass
investigation
because
percentage
the
it
is
initial
change
in
necessary
masses
mass
is
of
the
to
calculate
the
tissue,
length
potato
derived
the
percentage
pieces
variable.
It
temperature,
of
volume
results.
of
In
of
below.
are
is
change
different.
calculated
in
Can
The
solution.
you
think
of
variables? There
as
control
variables
any
is
more
more
on
control
about
page
59.
follows:
change
in
mass
______________
percentage
change
×
=
original
Concentration of
sucrose
100
mass
Initial
Final
Change
in
Percentage change
Mean
solution/mol dm
mass/g
mass/g
mass/g
0.0
1.26
1.49
0.23
18.3
1.23
1.51
0.28
22.8
1.22
1.43
0.21
1.22
1.31
0.09
1.28
1.32
0.04
3.
1
1.25
1.31
0.06
4.8
1.43
1.29
–0.
14
–9.8
1.32
1.26
–0.06
–4.5
1.34
1.25
–0.09
–6.7
1.32
1.
10
–0.22
–16.7
1.26
1.07
–0.
19
–15.
1
1.22
1.05
–0.
17
–13.9
1.28
0.98
–0.30
–23.4
1.25
1.01
–0.24
–19.2
1.23
0.97
–0.26
–21.
1
1.3
0.95
–0.35
–26.9
1.27
1.01
–0.26
–20.5
1.23
0.96
–0.27
–22.0
percentage
in
change
–3
0.2
0.4
0.6
0.8
1.0
mass
in
mass
19.4
17
.2
7
.4
5.
1
–7
.0
–15.2
–21.3
–23.
1
41
Module
1
Cell
and
molecular
biology
Three
there
pieces
is
in
were
the
concentration
pieces
of
rather
than
These
results
used
results.
then
potato
all
you
cannot
in
the
are
for
If
each
there
can
be
say
little
that
labelled
same
plotted
concentration
is
the
so
to
variation
results
they
are
see
in
are
put
how
the
much
results
reliable.
into
for
The
separate
variation
each
three
test-tubes
container
.
on
the
following
graph.
20
15
10
ssam
5
ni
egnahc
0
egatnecrep
5
10
15
20
25
0.0
0.2
0.4
0.6
0.8
1.0
3
concentration
Figure 2.8.2
of
sucrose /mol
dm
Graph to show the effect of immersion of potato storage tissue in different
solutions of sucrose
The
Link
curve
there
Use
the
data
conversion
on
page
graph
so
45
you
to
plot
a
can nd
the
is
drawn
no
we
can
we
could
on
change
use
this
the
in
graph
mass.
intercept
predict
that
it
passes
This
on
the
would
did
through
not
graph
to
happen.
zero
happen
find
Use
the
the
per
in
cent
any
of
at
the
which
results,
concentration
intercept
at
zero
at
but
which
per
cent
–3
water
potential
storage
in
kPa
of
the
potato
to
find
the
concentration,
which
is
0.28 mol
dm
tissue.
The
changes
in
water
between

solutions
texture,
the
length
tissues
and
and
the
mass
are
sucrose
the
result
of
movement
of
solution.
–3
In
osmosis
more
out
decrease
in
of
concentrated
the
cells
into
than
the
0.28 mol
solution
so
dm
the
water
pieces
of
moves
by
tissue
size.
–3

In
solutions
osmosis
S tudy
of
is
there
water,
no
net
it
from
concentrated
the
surrounding
than
0.28 mol
solution
into
water
dm
the
cells
so
moves
the
by
pieces
of
foc us
tissue
When
less
is
is
no
overall
movement
best
to
state
that
diffusion
of
water

In
increase
the
solution
movement
there
move
by
in
of
and
membranes
osmosis.
solution
in
in
which
water
.
out
do
like
size.
of
not
this.
In
there
this
the
cells
there
no
change
through
suddenly
So
is
solution,
is
become
no
net
water
the
in
mass
there
molecules
cell
surface
impermeable
diffusion
of
are
is
no
still
overall
able
membranes.
when
water
put
by
in
to
The
a
osmosis.
Plasmolysis
Investigations
see
the
was
in
onion
42
1
changes
the
and
that
blood
scale
3
cells
leaves
to
were
occur
in
see
carried
to
the
out
Investigation
the
with
individual
changes,
2.
W
e
such
plant
cells
can
as
tissue
in
the
use
those
and
it
is
difficult
to
storage
tissue
as
epidermal
tissue
from
in
Investigation
4.
it
Module
Investigation
1
Cell
and
off
the
epidermis
enough
to
fit
sucrose
or
salt
microscope
under
the
below
and
slide
a
of
an
cover
leave
in
the
microscope
onion
slip.
them
Put
for
solution
and
scale
look
the
10
in
leaf
pieces
cells
Put
they
like
cut
into
into
minutes.
which
for
and
different
each
were
those
pieces
solutions
piece
on
immersed.
in
the
Figure
increase
surface
this
the
of
turgor
volume
potential.
cells
with
by
of
water
the
as
it
high
the
has
Cells
moves
vacuole,
against
pressure
solutions
the
distilled
membrane
pressure
In
2.8.3 a,
cell
an
filled
which
wall.
equal
with
Most
of
water
the
each
of
cell
pushes
The
and
concentrations
osmosis.
into
the
of
When
Observe
and
like
this
sucrose
force
are
or
comes
cell
wall
salt,
and
cell
withstands
known
organisms
terms
osmosis
water
potential.
isotonic
always
It
and
between
is
not
the
cells
refer
best
hypotonic,
since
behaviour
solutions,
as
happens
water
the
about
of
to
to
use
hypertonic
or
to
turgid
from
in
water
photographs.
osmosis
writing
movement
a
cytoplasm
cellulose
opposite
water
by
foc us
small
the
In
biology
4
S tudy
Peel
molecular
moves
vacuole
of
they
cells
they
to
describe
in
do
the
different
not
explain what
them.
out
that
a
decreases
the
cell
in
size,
wall.
membrane
have
In
lost
space
with
and
their
distilled
solution
The
fills
plasmolysis
pulling
water
all
this
and
the
the
the
external
in
turgidity
increases
cytoplasm
between
the
cells
the
cell
cells
are
of
and
the
cell
from
surface
condition
plasmolysed.
away
is
known
Cells
like
as
this
(soft).
turgid.
percentage
membrane
This
are
flaccid
cell
wall
solution.
condition
are
and
As
the
concentration
plasmolysed
cells
of
increases
the
salt
until
at
–3
0.5
mol
all
dm
concentration
pushing
to
the
In
the
against
pressure
water
into
the
cell
3,
the
over
time
not
wall
the
the
Figure
therefore
potential
cell
storage
was
(see
plasmolysed,
and
water
of
solutions
plasmolysed
are
The
potential
the
However
,
are
cells
potential.
Investigation
put
cells
contents
tissue
very
pieces
of
the
this
in
cell
cell
wall
salt
was
This
placed
the
cut
means
two
of
At
is
not
and
from
that
the
a
b
certain
contents
solution
(cytoplasm
that
firm.
but
2.8.3 b).
are
not
exerting
is
any
equivalent
vacuole).
the
the
potato
cells
solutions
and
are
turgid.
gained
mass
Figure 2.8.3
a The cells are fully turgid as
–3
as
water
The
diffused
cells
were
into
able
the
to
cells
absorb
(see
0.0
some
and
water
0.2
to
mol
in
dm
become
more
Figure
turgid.
2.8.2).
they are immersed in distilled water; b the
cells are plasmolysed as they are
This
immersed in a solution with a high
means
that
the
cells
from
the
freshly
cut
tissue
were
not
fully
turgid
as
concentration of salt
they
have
diffuse
If
you
and
The
to
in
or
take
then
mass
absorbed
as
put
water
absorb
and
storage
the
negative
out
it
water
.
potential
water
is
of
we
to
has
water
fully
The
have
reach
will
and
cells
is
water
seen
were
been
it
turgid
these
zero.
as
that
into
are
pieces
tissues
tissue
back
cells
figure
the
The
left
in
water
not
0 kPa
for
show
there
the
enough
equilibrium
is
of
tissue
in
12
any
no
the
for
means
freshly
for
absorbs
weigh
to
more
their
tissue
Summary questions
it
increase
any
that
cut
water
solutions.
hours,
further
space
which
potential
that
long
1
in
be
plants
are
adapted
to
live
in
dry
soils
and
in
from
soils;
they
Explain,
using
soils
by
with
a
osmosis.
very
T
o
low
water
maintain
a
potential.
water
W
ater
potential
is
must
have
water
potentials
lower
than
those
of
the
writing
about
osmosis
and
the
movement
of
the
water
investigations
between
Y
ou
may
text
books
in
cells
find
the
and
different
hypotonic
and
their
terms
on
environment,
hypotonic,
websites.
solutions;
solution
is
they
one
These
do
in
not
always
hypertonic
terms
cells
and
describe
explain
which
refer
what
to
between
water
isotonic
the
in
is
one
in
which
they
decrease
in
volume
used
to
in
of
them.
volume;
and
an
Explain
a
one
in
which
they
do
not
increase
or
decrease
in
volume,
concentrated
or
lack
gradient.
of
them,
If
cells
can
gain
be
explained
water
by
in
terms
osmosis
the
of
The
the
water
ii
burst
when
distilled
A
external
Plants,
the
in
solution
external
into
or
out
gradient
volume
is
higher
solution.
of
and
the
the
that
Y
ou
cells.
is
water
than
that
In
why
can
an
the
potential
of
say
that
isotonic
cells
of
the
the
cell
there
is
solution
remain
the
cells
or
a
is
higher
water
there
same
is
If
a
water
volume.
salt
in
solution;
placed
into
water.
such
as
sea
lavender
mangrove,
which
has
live
a
in
very
very
low
salty
water
Explain
how
you
would
of
the
water
potential
of
the
cell
than
potential
no
do
water
potential
tissue.
i
when
changes
root
decreases
cells:
solution
nd
the
on
older
cells
potential.
potential
animal
plasmolysis
a
soil,
in
2
hypertonic
isotonic
volume.
why
show
and
is
and
cells,
4
solution
1
40.
potential.
behaviour
happens
increase
water
obtained
soils.
not
or
term
results
root
3
When
the
absorbed
gradient
page
tissues
the
absorb
in
passively
osmosis; water
water
.
salty
potential,
water
terms
flaccid; plasmolysis.
a
2
Some
the
pressure; pressure potential;
ability
will
Dene
potential gradient; turgid, turgor
water
.
that
tissue
of
these
plants.
of
gradient
potential
43
2.9
Cell
summary
Cells
can
be
a
rewarding
topic
to
revise
as
it
links
to
so
many
other
Learning outcomes
topics.
T
o
begin
with
here
are
some
ideas
for
activities
to
assist
revising
‘cells’.
On
completion
should

be
able
organise
of
this
section,
you
to:
information
about
cells
show
how
the
different
parts
cell.
al
anim
of
a
cell
help
it
diagra
large
a
and
cell
to
to function
or
A3
e
som
use
efciently

use
a
graphic
information
link
the
organiser
about
structure
to
cells
of
display
and
to
organelles
tions
func
to
their functions
tures
str uc
ou
Y
use
data
graphs
provided
to nd
potentials
and
of
sodium
to
the
plot
graphic
of
organiser
For
make
a
example
spider
together
it
your
you
all
diagram
the
have
is
chapter
.
See
facts
covered
below
you
started.
‘cells’
in
paper
and
aspects
the
you
W
rite
middle
then
of
the
down
Then
so
for
the
of
think
topic
a
one
good
make
of
the
you
have
sheet
of
and
links
spend
to
covered
between
these
for
links
answering
with
the
questions
of
exam
doing
we
this
have
you,
but
also
with
given
others.
try
if
of
more
the
terms
you
using
a
friend
technical
are
write
the
terms.
family
out
the
terms,
definitions.
or
Some
in
glossary
own
with
Y
ou
and
can
this
chapter
starting
longer
test
then
member
they
can
terms
time
learning
how
to
give
to
on
and
page
entries.
yourself
matching
read
read
are
out
very
out
the
by
in
178,
Also
printing
them
the
together
.
definitions
terms
similar
.
precise
and
Make
definitions
Thin
k
out
some
electron
all
identify
of
cells
so
organelles
you
from
learn
real
as
well
as
from
diagrams
you
sure
for
that
them.
from
prot
should
micrographs.
for
images
of
Search
of
organelles
different
types
of
specialised
that
one
eins
simple
mem
bran
es
e
bran
of
and
diffu
sion,
osm
osis
topic.
onlin
mem
for
es
as
static
.
anim
ation
s
show
the
acro
ss
activ
e
mov
of
the
phos
pholi
pids
diffu
sion,
and
not
that
also
subs
tance
s
by
prepare
questions
cell
str uc
tures
,
mov
emen
t
one
made
Searc
h
cell
the
drawings
of
dyna
mic
different
than
terms
the
your
other
on
Y
ou
will
in
separately
or
cell.
deal
with
type
practise
of
write
and
you
n.
draw
so
of
online
topics;
common
different
with
paper
.
idea
the
definitions
ask
call
the
electron
make
is
to
and
large
very
question,
central
links
finish
of
sentences
can
you
cells,
topics
This
word
piece
and
around
you
terms.
and
to
topics
a
could
glossary
Many
micrographs
word.
of
in
Print
them
pairs
to
you
get
a
out
provide
this
own
1.
terms
and
concepts
have
you
Or
collect
we
of
out
could
see
differentiate
sucrose
write
sort.
to
chloride.
but
some
you
the
ing
draw
ou
Y
cell.
summary
will
water
solutions
Chapter
a
a
the
you
line
Make
Make
asked
between
with
have
de
inclu
also
can
of
questions
ent
differ
you
that
tic
ar yo
prok
a

the
of
some
to
the
tate
anno
and
ms
diagra
In
able
d
r-size
poste
l
Labe
this.
for
r
pape
an
of
m
be
may
ou
Y
and
emen
facili
tated
trans
port,
bulk
flow.
mitochondria
graphic
for
.
r
organise
examples
concept
of
maps,
ry
T
mind
g
searchin
maps,
diagram
spider
s
organelles
eukaryotic
and
flow
charts,
and
also
find
cells
ions
instruct
them.
Use
graphic
a
about
variety
organise
revision
.
how
of
to
nucleus
make
different
cells
rs
to
help
your
prokatyotic
red
blood
cells
specialised
cells
sperm
44
t
mem
bran
es
cells
cells
Module
Make
a
poster
incorporating
of
all
cell
the
structure
diagram
s
specialis
ed
or
cells
photogr
aphs
information.
Y
ou
can
their
structur
e
and
is
identify
related
to
it
to
help
your
revision.
function
.
Here
examples
are
need
the
that
you
concentrations
to nd
the
potato
Investigation
the
with
table
red

pancrea
tic

pollen

human

human

palisade
blood
that
converts
the
to
water
water
potential
could
of

graph
some
research
:
a
biology
how
potentials
make
molecular
their
sucrose
use
and
of
You
important
Cell
Link
Find
most
1
storage
3
on
tissue from
page
40.
cell
exocrine
cell
grain
sper m
cell
g
followin
ovum
s:
heading
Name
cell;
of
Organ
system;
;
features
to
make
format.
your
the
table
e
structur
its
Plot
guard

white
blood
cell
–
phagocy
te

white
blood
cell
–
lympho
cell
probably
e
landscap
tion
informa
explain
each
cyte
have
cell
how
is
in
the
related
to
.
function
conversion
chloride
sodium
that
the
to
of

al
Structur
in
table
Use
cell
Organ;
n.
Functio
will
you
this
do
o
T
Tissue;
1
and
graphs
sucrose
chloride
MPa
=
when
1000
Concentration of
so
that
you
solutions.
can
Y
ou
answering
find
will
the
need
Questions
water
the
8
potential
conversion
and
9
on
page
of
sodium
graph
47.
for
Note
kPa
sodium
Water
potential/
Concentration of
–3
chloride/mol dm
0
Water
potential/
–3
MPa
0
sucrose/mol dm
0
MPa
0
0.
1
−0.440
0.
10
−0.260
0.2
−0.850
0.20
−0.540
0.3
−1.260
0.30
−0.860
0.4
−1.680
0.40
−1.
120
0.5
−2.
120
0.50
−1.450
0.6
−2.570
0.60
−1.800
0.7
−2.970
0.70
−2.
180
0.8
−3.420
0.80
−2.580
0.9
−3.860
0.90
−3.000
1.0
−4.320
1.00
−3.500
45
2.
10
Practice
Cell
On
page
22
questions
another
we
introduced
which
type
of
have
one
exam-style
structure
you
to
correct
multiple-choice
and function
multiple-choice
answer.
question
But
that
2
there
you
questions:
Four
is
plant
following
cells from
water
the
two,
on
your CAPE
three
which
or
Biology
even four
combination
is
Paper
answers
correct.
1. This
and
Here
you
are
type
have
some
has
to
The following
are found
1
microvilli
2
cilia
3
receptor
4
cellulose
5
glycoproteins
on
the
surfaces
surfaces
3
4
decide
water
potential/MPa
−0.76
−1.34
−0.65
−1.01
of
cells
are
all
in
contact
1
B
3
C
1
as
shown
in
and
Figure
2.
10.
1.
cells.
cell
1
4
proteins
cell
2
wall
the following
of
the
2
cell
of
have
1
cell
A
root
examples.
cell
Which
a
one,
The
1
of
can
cell
expect
cortex
potentials.
animal
are
NOT found
on
3
the
cells?
2
Figure 2.10.1
and
5
In
and
which
direction
between
D
Read
4
only.
the
list
area;
proteins
and
membrane
found
cells
the
cilia
to
of
D
is
bring
interact
the
surrounding
so
surface
–
the
two
are
with
the
cell
structures
to
increase
movement.
part
there
be
movement
of
water
cells?
of
the
cell
cell
surface
walls
A
3
B
2
C
1
D
4
to
4
and
2
that
to
1
and
3
4
and
2
the
to
Receptor
molecules from
cell. Cellulose
right
are
microvilli
about
glycoproteins
and
environment
the
(K)
carefully. The rst
protrude from
surface
will
3
the
are
membrane
to
2
and
1
(U
of
K)
surface
outside
only
of
To
answer

plant
as
you
this
add
potential
question
more
you
solute
need
to
a
to
know
solution
three
the
things:
water
decreases
answer.

water
moves
region

of
down
higher
water
potential
water
potentials
−0.65
is
the
a
water
water
are
highest
potential
potential
given
to
a
negative
water
gradient from
region
of
numbers,
potential
and
a
lower
so
−1.34
is
the
lowest.
Water
can
each
are
in
given
and
the
lower
water
B
and
also
one
the
of
question
work
out
between
between
as
is
the
question. Cell
potential
−0.76 MPa,
you
potential
Water
move
other,
the
water
than
Check
46
only
touching
of
the
Try
these
are
all SAQs.
has
high
be
the
will nd
water
is
which
cannot
should
3
going
to Cell
answering
anotate
answer.
Here
that
two
the
you
2,
you
potential
cells
right
are
answer.
against
the
happen.
but
this
that
type
diagram
could
are
choices
water
neighbouring
must
moves from Cell
the
cells
with
gradient,
options. When
you
1
the
so C
the
case
to
draw
is
not
of
help
you
arrows
cells.
questions for
yourself
as
exam
practice. These
Module
3
This
is
a
list
functions
of
(1
organelles
to
8).
Match
(A
to
the
H)
and
a
list
organelles
of
with
cell
8
their
of
functions.
A
cell
The
into
surface
1
storage
membrane
of
genetic
information
table
red
shows
blood
the
cells
different
1
Cell
results
after
a
and
of
molecular
counting
sample
of
biology
the
blood
is
number
placed
solutions.
Concentration of
Percentage of
sodium
cells destroyed
chloride
red
blood
by
–3
B
Golgi
C
rough
body
endoplasmic
2
endocytosis
3
formation
reticulum
secretory
haemolysis
0.00
100
0.02
100
0.04
100
0.06
80
0.08
45
0.
10
28
0.
12
12
0.
14
0
0.
16
0
0.
18
0
0.20
0
0.22
0
0.24
0
of
vesicles
D
nucleus
4
formation
of
proteins
E
lysosome
5
formation
of
lipids
F
smooth
6
respiration
endoplasmic
solution/mol dm
reticulum
G
nucleolus
7
production
of
ribosomes
H
mitochondrion
8
storage
of
hydrolytic
enzymes
4
State THREE
that
5
a
are
Draw
least
b
a
in
diagram
50 mm
Assume
is
structural features
not found
the
in
of
eukaryotic
of
a
prokaryotic
cells
cells.
mitochondrion
that
is
at
a
Plot
a
b
State
graph
of
these
results.
length.
actual
length
3.5 µm. Calculate
the
of
the
the
water
potential
at
which
50%
of
the
mitochondrion
magnication
of
cells
are
destroyed
(Use
the
graph
page
45
to nd
by
haemolysis.
your
you
drew from
the
table
on
drawing.
c
Explain
some
cells
have
large
numbers
Explain
9
The
fertilised
eggs
without
cut
do
not
into
why
mitochondria
are
thought
to
a
Draw
a
50 mm
b
Show
diagram
prokaryotic
of
some onion
placed
in
scale
solutions of
sodium
a Golgi
immersed for ten
chloride. The
minutes
and then
have
microscope
slides
in the
bathing
solutions.
cells.
The
6
and
concentrations of
placed on
developed from
peeled off
pieces
survive.
pieces were
Explain
results.
any functional
different
mitochondria
the
epidermis was
leaves,
d
potential.)
of
mitochondria
ii
water
why:
c
i
the
body
that
is
at
least
at
number of
random was
plasmolysed
cells
counted. The
in
100
results
are
cells
chosen
shown
below.
across.
on
your
diagram
how
a Golgi
Concentration of
body forms
sodium
Percentage of
–3
chloride
secretory vesicles.
c
Describe
what
containing
happens
substances
to
are
plasmolysed
0.00
secretory vesicles
that
solution/mol dm
exported from
cells
0
0.
10
7
cells.
d
State
one function
production
7
a
Make
cell
b
a
c
State
d
Use
the
the
the Golgi
body
other
0.20
43
0.30
67
0.40
87
0.50
100
than
secretory vesicles.
simple
surface
Label
of
of
drawing
to
show
the
structure
of
a
membrane.
components
width
of
the
of
the
membrane.
membrane.
a
Plot
b
State
a
cells
your
diagram
to
explain
how
polar
across
the
are
of
these
water
results.
potential
plasmolysed.
at
(Use
which
the
50%
graph
of
you
the
drew
molecules
from
pass
graph
the
the
table
on
page
45
to nd
the
water
membrane.
potential.)
c
Explain
how
plant
cells
become
plasmolysed.
47
1
Cell
3.
1
Enzymes
and
molecular
Learning outcomes
Enzymes
Catalysts
On
completion
of
this
section,
be
able
dene
the
terms:
catalyst;
site; activation energy
explain
that
proteins
to
enzymes
that
are
catalyse
globular
broken
that
enzymes
are
specic

other
study
are
detailed
catabolic
are
those
and
the
page
→
surface
closely
Substrates
Enzymes
complex
are
glucose
maltose
→
and
by
the
in
study
anabolic
are
those
shown
check
also
glycosidic
In
n−1
about
the
fatty
→
fructose
acids
by
of
by
acids
substances
to
is
reactions
making
a
you
(amino
molecules
bonds
→
between
starch
+
acids,
a
for
number. Think
peptide
how
out
many
of
nine
3.1.1
the
water
are
How
The
shape
into
it.
→
into
the
the
to
the
of
breakage
Now
site
to
molecule ts
because
shape
48
write
as
bond
glycosidic
bonds
of
peptide
bonds
glycerol
by
breakage
of
ester
bonds
by
breakage
of
phosphodiester
bonds
by
forming
bonds,
such
as:
glucose
monomers
in
starch:
amino
acids
in
a
polypeptide:
polypeptide
+
(water)
how
t.
enzymes
There
active
the
idea
site
the
the
site
of
are
is
the
such
lock
enzyme
substrate
so
catalyse
two
that
and
is
in
the
a
by
which
As
may
can
substrate
changes
better
providing
this
substrate
key .
molecule
there
reactions
ways
t
shape
t
a
place
happen.
very
closely
molecules
slightly
between
the
to
t
mould
This
mode
of
action
is
known
as
an
induced
fit.
two
Only
with
For
the
appropriate
example,
shape
amylase
of
will
active
accept
site
will
starch,
accept
but
not
a
a
specic
protein.
is
specic
to
the
breakdown
of
starch
and
catalyses
the
of
every
specificity
which
of
must
other
an
be
glycosidic
enzyme
is
bond
to
form
determined
complementary
to
the
by
maltose
the
shape
shape
of
the
(a
of
disaccharide).
its
active
substrate.
This
foc us
complementary
not
glycosidic
you
means
substrate
a
question.
site,
active
of
the
The
A
are
are:
specic
to
the
is
around
hydrolysis
S tudy
Examples
molecules
in
reactions?
answer
changed
n–1
shows
active
Amylase
have
are
This
substrate.
condensation
be
peptide
many
eliminated
ones.
to
substrates
n–1
substrate
enzymes
of
are
which
of
reaction
synthetase
molecules.
bonds form?
the
(water)
between
acids)
Enzymes
itself
amino
made
will
photosynthesis.
large
make
that
in
simpler
breakage
and
nucleotides
build
bonds
Peptide
reactions.
foc us
n
are
substrates
synthetase
peptide
Figure
S tudy
so
or
on
your
anabolic
of
substrate
doing
n
Other
the
reactions
molecules
n
to
and
catalyse
breakage
amino
→
acids
(glucose)
of
which
of

2
on
Nucleases
Link
page
without
that
of
decomposition
as
a
together
occur
.
triglycerides
Starch
to
reaction
catalysts
reactions

understanding
a
Lipase
on
54.
Refer
of
Proteases
Enzymes
peroxide
t
from
→
nucleic
hydrogen
to
provide
reaction.
polypeptide
reactions
respiration
can
down
starch

will
rate
biological
Amylase
reactions.

you
the
are
Sucrase
Link
2. The
increase
Enzymes
metabolic

page
the
sucrose
particular
Catabolic
that
themselves.
They
likely
during

explain
substances
up
reaction
more
reactions

used
protein.
the
enzyme; substrate; product ; active

are
catalysts
to:
of

are
you
being
should
biology
has
shape.
that
the
it
it
active
has
into
an
a
only
Remember
the
site.
There
same
of
that
are
to
have
different
one
reactions
cut
they
peptide
degrees
reaction.
of
the
bonds.
shapes
of
Others
same
that
specicity
are
type.
match
less
For
or
t
and
specic
example,
together
.
some
and
the
enzymes
will
table
are
catalyse
shows
a
specic
number
enzymes
that
Module
Enzyme
Specicity
pepsin
next
–
breaks
peptide
1
bonds
products
substrate
to
phenylalanine,
glutamic
acid
and
leucine

trypsin
next
to
arginine
or
lysine
chymotrypsin
next
to
phenylalanine,
tyrosine
and
tryptophan
enzyme
exopeptidases
at
the C
and
subtilisin
between
N
terminals
of
enzyme–substrate
complex
peptides
Figure 3.1.1
Active
any
pair
of
amino
acids
The mode of action of an
enzyme
sites
Did you know?
An
active
site
is
a
‘pocket’
in
an
enzyme
molecule.
This
is
lined
by
There
R-groups
of
some
amino
acids
that
are
close
to
each
other
after
are
thousand
enzyme
molecule
is
folded
into
its
tertiary
shape.
Some
of
the
thought
different
making
sequence,
it
determines
inside
or
the
some
the
form.
site
not.
which
active
The
substrate
active
are
are
The
substrate
site
the
adjacent
shape
can
molecule
combination
of
to
made
t.
is
other
in
the
the
R-groups
When
the
substrate
put
enzyme
each
by
under
and
strain
substrate
so
is
is
an
over
a
in
human
some
cells.
primary
important
molecule
that
be
enzymes
amino
specialised
acids
to
the
bonds
as
ts
break
enzyme-
Summary questions
complex
1
Dene
the following
terms:
catalyst; enzyme; substrate;
Activation
energy
product.
The
reactions
catalysed
by
the
enzymes
described
above
are
not
2
favourable.
They
require
the
formation
and
breakage
of
covalent
Explain
why
necessary
Covalent
bonds
are
stable
bonds,
which
require
energy
to
form
and
3
activation
a
in
each
why
are
there
are
Write
a
word
energy
the
equation
synthesis
of
energy
start
to
a
necessary
triglyceride from fatty
to
so
cell.
energy –
show
the
and
break.
many
energy
enzymes
bonds.
the
acids
reaction
in
and
glycerol.
substrate
b
State
the
name
that forms
acids
energy
4
in
the
the
bond
between fatty
glycerol.
specicity
of
enzymes.
products
reaction
Figure 3.1.2
Explain
and
of
time
5
Activation energy
Describe
an
the
enzyme
mode
using
of
the
action
of
induced t
mechanism.
Activation
energy
is
the
energy
that
must
be
overcome
before
a
reaction
6
can
proceed.
Much
energy
is
needed
to
make
or
break
the
covalent
a
Write
out
sequence
in
the
reactions
involving
biological
molecules.
Enzymes
provide
where
activation
occur
so
substrate
energy
slowly
is
that
molecules
overcome.
life
would
are
positioned
Without
not
exist
in
enzymes
as
we
such
the
know
a
way
that
reactions
of
primary
a
polypeptide
active
with
sites
the
bonds
20
different
amino
acids
the
that
would
includes
adjacent
it.
lysine
and
b
pairs
and
of
amino
leucine,
acids:
arginine
phenylalanine.
Show
on
your
sequence
be
the following
broken
given
in
the
by
the
primary
bonds
the
table
that
will
enzymes
above.
49
3.2
Investigating
The
Learning outcomes
enzyme
activity
reaction
On
completion
should
be
able
of
this
section,
you
now

describe
how
progress
of
to follow
they
and
ready
the
to
is
When
collide
form
enzyme
to
product
determined
form
nding
molecules
are
leave
the
the
to
at
which
sites.
complex.
a
substrate
complexes.
active
enzyme-substrate
rate
added
enzyme-substrate
molecules
another
by
A
The
reaction
enzyme
Over
time
is
the
the
number
an
enzymes
proceeds.
molecules
occurs
to:
of
activity
of
substrate
molecules
decreases
and
the
chance
of
a
substrate
enzyme-catalysed
molecule
entering
an
active
site
decreases.
This
means
that
the
number
reaction
of

describe
how
to
use
product
to follow
of
explain
as
how
1/t for
to
can
it
follow
takes
the
to
course
reach
an
of
an
end
enzyme-catalysed
point.
For
example
a
reaction
by
solution
of
seeing
milk
how
protein
starch
is

decreases.
the
long
disappearance
formed
iodine
Y
ou
solution
molecules
calculate
rates
cloudy.
as
Add
a
protease
and
the
cloudiness
disappears.
This
can
be
done
follows:
enzyme-catalysed
3
1
Add
10 cm
of
a
solution
of
milk
powder
to
test-tube
1.
reactions
3

create
from
tables
to
practical
record
2
Add
3
Put
4
After
both
of
a
protease
test-tubes
in
solution
a
water
to
bath
test-tube
at
30 °C
2.
for
ve
minutes.
investigations.
5
S tudy
1 cm
results
ve
minutes,
return
the
W
atch
carefully
pour
test-tube
1
and
to
the
the
time
contents
water
how
of
bath
long
it
test-tube
and
takes
start
for
2
a
the
into
test-tube
1,
timer
.
cloudiness
to
foc us
disappear
.
Keeping
the
substrate
they
are
enzyme
solution
both
at
solution
separately
the
The
and
until
desired
time
is
short
time
taken
temperature for
the
reaction
is
taken
there
a
to
fast
for
rate
and
reach
the
of
you
an
reaction
reaction
can
end
to
then
calculate
point
in
occur
the
the
is
not
reaction
rate
as:
the
rate
will
1/ t
in
be
of
reaction.
completed
which
t
=
the
If
in
a
time
seconds.
called
equilibration
–1
The
In
unit
many
for
rate
cases
disappearance
amylase
it
is
is
better
solution.
them
this
is
is
to
not
to
follow
do
this
the
added
T
o
with
it
of
in
this
iodine
case
is
possible
cloudiness
starch,
the
you
to
as
there
take
see
of
change
milk
be
a
record
from
the
as
such
protein
slight
starch
samples
and
a
the
may
hydrolysis
solution
–1
(written
seconds
by
the
s
).
as
is
that
change
testing
in
the
Figure
If
cloudiness
with
reaction
colour
.
for
hydrolysed.
mixture
3.2.1
and
shows
test
how
done.
03:00
samples
of
taken
15
at
reaction
second
mixture
intervals
sample
of
reaction
in
mixture
pipette
A
B
water
S tudy
foc us
at
testing
30 °C
reaction
Taking
a
sample
as
soon
as
is
added
to
the
mixture:
amylase
iodine
substrate
starch
D
is
suspension
spotting
1
2
3
called
taking
a
reading
at
‘time
zero’.
Figure 3.2.1
50
with
solution
the
and
enzyme
C
Following the hydrolysis of starch
but
iodine
tile
Module
Y
ou
should
continue
taking
samples
until
two
results
give
a
yellow
1
Cell
and
recorded
that
in
a
all
the
starch
has
been
hydrolysed.
These
results
table:
not
Time/seconds
Colour of
iodine
solution
Starch
the
results
know
all
the
starch
Therefore
blue-black

15
blue

30
red-brown

60
yellow

90
yellow

0
the
‘between
making
make
the
draw
it

draw
the

write

columns
a
table
table
right
table
brief
a
at
to
record
reasonable
the
top
of
outlines
but
a
with
size
follow
and
not
this
too
(see
page
41
for
small;
remember
not
the
rst
column
is
30
and
headings
physical
rows)
for
in
left

might
of
what
the
each
quantities
independent
contain

data
write
short
should
arrange
(i.e.
put
a
independent
you
words,
to
the
down
in
the
and
be
the
body
the
of
or
–
variable;
the
so
that
letter
for
the
phrases,
organised
of
have
appropriate
numbers
only
the
second
the
solidus
in
or
Write
variable(s);
in
the
example,
table
patterns
independent
to
should
numbers,
rst
word
how
equations
have
to
into
the
the
body
column
slash
include
3
per
dm
be
ticks
can
identify
or
be
variable
brief,
e.g.
–
of
the
table
do

note
as
g/dm
that
g dm
it
2
a
take
etc.
best
is
and
in
the
which
are
starch,
triglyceride.
meant
Suggest
single
is
ascending
What
to
3
order
a
why
result
Explain
why
hydrolysis
not
have
units
(units
by
it
is
at
time
the
of
time
zero?
important
rate for
milk
to
zero.
the
protein
is
(/)
.
.
It
meaning
‘per ’
concentrations
should
seconds
not
should
not
be
used
in
units.
Calculate
in
a
table
you
should
not
always
be
written
out
in
full
write
using
the
rate
of
reaction
If
the
results
in
the
table.
g
‘per ’
or
,
5
Students
often
suggest
that
–3
The
solidus
it
using
minutes.
negative
is
used
exponent,
to
separate
cm
,
what
means
is
‘per ’
measured
from
iodine
solution
to
starch-amylase
the
is
examination
measured.
papers
use
Y
ou
may
brackets
notice
around
that
the
many
units
text
in
should
be
added
reaction
the
mixture
unit
protein,
headings)
–3
better
,
a
the
test-tubes
crosses,
seen
in
to
3
as
to
the following
sometimes
column
from
you
seconds’.
and
4

is
table)
written
appear
60
answer
SI
calculated

hydrolysed.
precise
Summary questions
column
should
dependent
number
variable
descriptive
values
be
examples)
the
columns
want
do
took
pencil
sucrose,
you
to
most
hydrolysed:
subsequent
we
it
to
show

table
long
guidance:
1
units
the
how
page
(columns
informative
headed
results
in
exactly
present
for

foc us
are
From
When
biology
colour
S tudy
indicating
molecular
at
time
zero
so
that
the
books
colour
tables.
change
without
why
6
this
Describe
is
biuret
7
is
should
precautions
take
when
investigation
valid
at
hydrolysed
disappearance
iodine
would
rate
which
using
a
the
test.
List four
an
Suggest
done.
you
the
be followed
samples.
not
how
determine
protein
can
taking
to follow
of
solution
you
carrying
starch
so
that
out
the
using
you
obtain
results.
51
3.3
Quantitative
In
results
the
investigation
outlined
in
Section
3.2
the
results
are
qualitative.
W
e
Learning outcomes
do
not
know
how
much
starch
has
been
hydrolysed.
If
–3
concentration
On
completion
of
this
section,
be
able
the
solution
is
we
know
the
3
then
10 g dm
10 cm
contains
1/100
of
the
you
mass
should
of
of
starch
=
0.1 g.
So
in
60
seconds
0.1 g
of
starch
is
hydrolysed
and
–1
can

explain
the
difference
calculate
and
the
rate
as
0.1/60
=
–1
(grams
0.002 g s
per
second)
or
2 mg s
between
The
qualitative
we
to:
rates
calculated
from
the
results
in
Section
3.2
are
the
overall
rate
quantitative
for
the
complete
hydrolysis
of
the
substrate.
As
the
substrate
results
concentration

describe
how
to
results
it
reaches
the
hydrolysis
of
draw
graphs
to
show
practical
the
rate
the
end
point
when
the
reaction
must
stops.
If
slow
we
down
can
readings
at
intervals
we
can
see
if
this
take
happens.
concentration
of
starch
can
be
determined
using
a
colorimeter
to
results from
measure
a
reaction
starch
The

the
when
quantitative
following
during
obtain
until
quantitative
decreases
the
optical
density
of
the
starch–iodine
complex.
investigation
–3


explain
how
to
use
a
Make
a
solution
10 g dm
of
starch
and
use
it
to
make
up
these
calibration
solutions:
graph.
–3
0.75,


For
a
description
complex
see
Add
equal
volume
Link
of
page
the
Place
of
each
0.50,
volumes
iodine
of
0.25,
each
solution
test-tube
in
a
0.10,
0.07,
solution
to
each
to
0.05,
0.01 g dm
test-tubes
and
the
same
test-tube.
colorimeter
to
measure
the
optical
density.
starch–iodine
Optical
18.
density
may
be
measured
using
absorbance
or
percentage
transmission.
This
table
gives
some
colorimeter
readings
for
known
concentrations
of
starch.
–3
Concentration of
S tudy
are
Using
milligrams
1000
less
a
avoids
of
micrograms
smaller
in
milligrams
than
concentrations
see
Colorimeter
0
0.00
1000
0.30
2000
0.52
3000
0.70
4000
0.85
5000
0.96
6000
1.06
reading:
foc us
There
numbers
starch/mg dm
in
a
writing
1.0 for
very
starch. You
(µg)
gram.
used for
quantities. There
are
low
may
even
1000 µg
mg.
7000
8000
1.24
9000
1.28
10
000
These
52
1.
15
results
1.30
are
plotted
on
a
graph,
see
Figure
3.3.1.
absorbance
Module
1
Cell
1.4
and
molecular
biology
Link
For
1.2
advice
best t’
on
on
how
graphs
to
draw
refer
to
‘lines
page
of
55.
1.0
ecnabrosba
0.8
0.6
0.4
S tudy
foc us
0.2
Notice
that
the
disappearance
rate
of
of
starch
is
not
the
0.0
same
0
2000
4000
6000
8000
throughout
the
time
period.
10 000
When
is
it
at
its
highest?
3
concentration
Figure 3.3.1
of
starch/mg
dm
This calibration graph allows you to convert colorimeter readings to
concentrations of starch
When
drawing
S tudy
graphs
you
should
follow
this
guidance:
Use

make
do
use
not

draw

the
of
the
graph
each
axis
in
makes
each
it
1,
easy
axis
too
for
should
you
use
at
least
half
the
grid
provided,
should
5
be
marked
or
you
be
10
to
be
plotted
with
for
an
each
plot
labelled
plotted
and
on
the
the
units
as
information
you
answer
on
page
50
Summary
1e.
extract
with
x-axis
and
the
y-axis
appropriate
20 mm
clearly
on
scale,
square
data;
the
on
never
e.g.
the
use
quantity
using
grid.
This
multiples
and
SI
of
unit(s)
3
or
–3
derived
the
help
question
small
should
be
2,
so
to
pencil
variable
variable
of
paper
graph
should
multiples

graph
the
independent
dependent

the
make
foc us
appropriate,
e.g.
time/s,
–1
,
concentration/g dm
rate/g s
–1
or

rate/s
plotted
lines;
points
use
should
must
dots
not
be
in
be
clearly
circles
used;
if
(
)
you
marked
or
need
saltire
to
and
easy
crosses
plot
three
to
(×);
lines
see
on
dots
on
the
on
a
grid
their
graph,
Here
are
some
vertical
Time/min
crosses
(+)
can
also
be
results:
own
Colorimeter
used.
reading:
absorbance
Summary questions
1
a
Copy
the
b
Use
the
table
of
results
concentration
the
each
sampling
c
Draw
d
Describe
e
Explain
a
of
calibration
graph
the
why
in
the
margin
and
add
a
third
column
to
show
trend
the
to
the
shown
rate
1.32
2
0.60
4
0.30
6
0.
10
8
0.09
10
0.08
12
0.06
14
0.04
16
0.01
starch.
graph
determine
the
concentration
of
starch
at
time.
to
0
show
of
starch
in
concentration
your
reaction
against
time.
graph.
is
not
constant
throughout
the
time
period.
2
Explain
of
3
the
advantage
hydrolysis
Suggest
follow
the
the
of
of
using
the
colorimeter
when
investigating
the
rate
starch.
precautions
you
disappearance
of
should
take
when
using
the
colorimeter
to
starch.
–3
4
Describe
how
to
make
the
dilutions
of
starch from
the
10 g dm
solution.
53
3.4
Determining
If
Learning outcomes
you
take
On
completion
should

be
able
explain
the
of
this
section,
the
follow
initial
the
samples
course
of
rate
an
of
reaction
enzyme-catalysed
reaction
you
can
either
to:
you

follow
the
disappearance

follow
the
appearance
of
substrate
to:
term
of
product.
initial rate of
From
the
graph
drawn
on
the
disappearance
of
starch
in
Summary
reaction
question

describe
how
to
determine
1c
rate
of
an
and
53
you
can
observe
that
the
rate
is
fastest
decreases
with
time
as
the
concentration
of
at
the
starch
reduces.
enzymeEventually
catalysed
page
the
beginning
initial
on
there
is
no
substrate
left
so
the
reaction
stops.
The
collisions
reaction.
between
enzyme
beginning
T
o
follow
which
is
of
the
in
Catalase
the
molecules
reaction
appearance
yeast
and
catalyses
is
the
and
as
of
the
a
product
common
O
2
is
possible
common
celery,
to
which
liquidised
catalase.
may
to
use
be
in
an
also
a
The
set
use
a
solution
extract
contains
blender
diagram
up.
Y
ou
in
and
of
the
of
2H
added
can
use
O
+
how
use
The
the
a
enzyme
and
at
the
plant
catalase,
tissues.
peroxide.
2
but
as
The
it
is
such
plant
ltrate
is
apparatus
gas
highest
substrate.
O
material,
enzyme.
were
the
the
hydrogen
catalase,
plant
to
animal
2
ltered.
also
we
2
from
shows
could
→
molecules
is
many
decomposition
2H
It
substrate
enzyme
syringe
potato,
material
the
for
to
expensive
as
is
extract
the
is
cut
and
following
collect
it
more
lettuce
the
or
up,
contains
reaction
oxygen
produced.
00:30
volume of
oxygen
determined
10
every
seconds
oxygen
collected
downward
of
water
at
reaction
bath
hydrogen
constant
and
temperature
Figure 3.4.1
mixture
by
displacement
water
–
peroxide
catalase
This shows how to follow the reaction in which hydrogen peroxide is
decomposed to oxygen and water
S tudy
You
may
shown
may
carry
here
also
foc us
be
this
is
collected
temperature
54
out
oxygen
is
a
investigation
collected
in
control
a
gas
by
with
different
downward
syringe. The
variable.
apparatus.
displacement
important
point
of
to
In
the
method
water;
note
is
oxygen
that
Module
The
table
shows
the
results
obtained
which
are
then
plotted
on
a
1
Cell
and
molecular
biology
graph.
Time/s
volume of oxygen
3
7
collected/cm
mc/detcelloc
3
0
6
0.0
10
2.6
20
3.9
30
4.8
40
5.4
50
5.7
60
5.8
70
5.9
80
6.0
90
6.2
100
6.2
5
4
negyxo
3
fo emulov
2
1
0
0
20
40
60
80
100
time/s
Figure 3.4.2
Graph to show the volumes of oxygen produced when an extract of catalase
is added to hydrogen peroxide
The
initial
rate

calculating

taking
a
is
determined
the
rate
tangent
from
to
the
by
the
either:
rst
curve
sample,
drawn
on
or
the
graph.
3
Using
the
second
Lines of
After
you
a
line
on
of
the
use
best
what
the
rate
in
this
example
is
−1
0.3 cm
s
.
best t
plotting
would
method,
you
to
t
points
show
which
are
on
the
a
graph
trend.
includes
you
In
all
have
most
or
to
cases
most
of
decide
you
the
what
should
points,
sort
look
but
of
to
this
line
draw
depends
investigating.
Summary questions
Y
ou
can
follow
these
points
for
guidance:
1

look
at
could
they

if
be
points
of
carefully
straight
be
points
place
side
a
could
the
to
the
do
your
the
on
line
a
that
curve
not
line
fall
so
–
in
do
you
can
which
neatly
you
they
have
on
use
case
a
the
fall
on
a
line
ruler
you
line
a
can
to
number
best
put
use
(straight
same
of
a
or
of
t?
on
the
exible
curved),
points
why
graph
determine
or
reactions
ruler
then
on
Explain
it
is
try
2
either
Describe
the
the
in
enzyme
how
initial
initial
to
rate
if
you
with
cannot
straight
see
a
lines
pattern
which
to
the
shows
results,
then
uncertainty
you
about
can
the
join
the
points
the
as
is
the
one
maximum
catalase,
four
such
as
of
the
fastest-acting
number
converts
to
polypeptide,
lysozyme,
comparisons
active
site
Enzyme
active
all
of
of
enzymes.
molecules
molecules
between
enzyme
and
collisions
With
are
the
of
of
and
enzymes,
is
depends
ability
that
which
smaller
and
between
enzymes
collisions
each
are
efciency
site
determine
of
reaction
of
of
hydrogen
Use
the
graph
you
drew for
variables.
of
The
substrate
product
turnover
that
per
unit
an
of
number
enzyme,
time.
is
to
such
a
active
have
only
the
the
the
site
high
an
active
have
one
turnover
measure
on
of
has
of
ease
of
enzyme
and
the
a
active
number
very
T
o
an
make
fair
per
and
reaction.
a
the
1c
on
initial
page
rate
53
of
reaction.
Predict
the
effect
Not
reaction.
proportion
of
such
the
substrate
of
increasing
the
initial
concentration
rate
and
explanation for
enzyme.
substrate
in
determine
enzymes,
calculated
of
the
result
high
site.
is
between
catalyse
substrate
efciency
Other
efciency
t
to
site.
question
Catalase
4
has
studies.
peroxide.
Summary
Catalase
to
of
relationship
3
between
rate
line
decomposition

important
This
5
Predict
the
the
effect
temperature
rate
of
reaction
explanation for
suggest
your
of
on
on
an
answer.
increasing
the
and
your
initial
suggest
an
answer.
successful.
55
3.5
Factors
influencing
V
arious
Learning outcomes
of
On
completion
should

able
this
effect
substrate
of
to
activity
explain
the
substrate
enzyme
investigate
of
effect
the
concentration
an
of
substrate

temperature.
of
Substrate
increasing
on
difference
competitive
inhibitors
substrate
active
molecules.
activity.
site
molecules
where
Here
we
Think
the
colliding
reaction
consider
about
two
our
with
occurs
and
model
enzyme
then
the
factors:
concentration
concentration
procedure
depicted
on
concentration.
concentration
the
of
enzyme
page
54
is
used
to
investigate
the
effect
of
enzyme-catalysed
reaction
state
terms
the
of
(1)
the
substrate

rate
activity
enzyme
concentration
an
product
the
in
entering

The
rate
of
affect
activity
molecules,
you
release
how
the
section,
to:
describe
on

be
of
factors
enzyme
and
and
as
The
procedure
is
repeated
for
each
substrate
follows:
between

decide
a
range

decide
on

prepare
of
hydrogen
peroxide
concentrations
to
be
used
non-competitive
explain
the
intermediate
concentrations
to
be
used
their
the
different
concentrations
by
diluting
the
20
volume
effects
3
hydrogen

describe
how
to
investigate
peroxide
of
temperature
of
an
on
explain
the
effect
temperature
means
that
when
of
1 cm
peroxide
is
decomposed,
20 cm
the
of
oxygen
are
produced.
−3
20
volume
solution
is
).
1.67 mol dm
enzyme
The

volume
3
A
activity
(20
the
hydrogen
effect
solution
on
of
the
table
shows
the
results.
increasing
rate
of
an
3
Concentration of
enzyme-catalysed
Volume of oxygen/cm
reaction.
–3
H
O
2
/mol dm
time/s
2
3
mc/detcelloc
negyxo
10
20
30
60
90
100
0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.0
0.7
1.4
1.9
3.2
4.4
4.6
0.4
0.0
1.3
2.
1
2.8
4.0
5.2
5.5
0.6
0.0
1.8
2.6
3.2
4.6
5.7
6.0
0.8
0.0
2.
1
3.2
3.9
5.2
5.9
6.0
1.0
0.0
2.0
4.0
4.8
5.8
6.0
6.0
6
5
4
3
1
fo
emulov
0
7
0.8
2
0.6
0.4
1
0.2
0
0
0
20
40
60
80
100
time/s
Figure 3.5.1
This graph shows the
progress of the reaction with different
concentrations of hydrogen peroxide
These
results
are
plotted
on
a
graph
(see
Figure
3.5.1).
0.3
1–
s
3
T
angents
mc/noitcaer
rates.
to
the
These
curves
are
then
in
Figure
plotted
3.5.1
on
are
another
used
to
determine
the
initial
graph.
0.2
Y
ou
can
see
from
Figure
3.5.2
that
as
the
substrate
concentration
fo
−3
increases,
the
rate
of
reaction
increases.
etar
3
0.
1
remains
laitini
At
a
the
0
0
0.2
0.4
0.6
0.8
constant
at
concentration
origin.
The
0.20 cm
of
rate
zero
After
the
0.8 mol dm
rate
−1
s
there
increases
was
as
no
more
reaction,
substrate
so
the
line
molecules
must
are
start
at
available
1
and
there
are
more
successful
collisions
with
the
active
sites
of
enzymes.
3
concentration
of
H
O
2
/mol
dm
2
−3
Figure 3.5.2
Up
until
the
concentration
the
concentration
the
rate
of
0.8 mol dm
enzyme
activity
is
limited
by
This graph shows how
of
substrate
because
if
the
concentration
is
increased
increasing the concentration of substrate
−3
increases.
At
concentrations
greater
than
0.8 mol dm
the
rate
is
influences the initial rate of the
decomposition of hydrogen peroxide by
catalase
56
not
limited
by
concentration
the
has
substrate
concentration
no
The
effect.
rate
must
because
be
increasing
limited
by
the
something
else.
Module
Some
substances
interact
with
enzymes
and
reduce
their
activity.
1
Cell
and
known
site
as
without
inhibitors.
being
Some
changed
in
inhibitors
a
reaction.
t
temporarily
These
are
inside
the
because
they
compete
with
the
foc us
active
competitive
Even
inhibitors
biology
These
S tudy
are
molecular
substrate
for
entry
to
the
if
you
did
not
have
the
result
active
−3
for
site.
If
the
concentration
of
the
substrate
is
increased
then
the
effect
0 mol dm
inhibitor
can
be
reduced
as
shown
in
Figure
not
inhibitors
than
the
compete
enzyme
longer
with
the
form
molecule
inhibitors
so
the
cannot
These
active
to
the
enzyme
be
are
site,
changes
complementary
cannot
temporarily
site.
reduced
bind
overall
substrate.
is
of
the
to
another
shape
and
enzyme
The
increasing
effect
the
site
the
on
of
the
active
as
they
do
enzyme.
site
is
no
complexes
non-competitive
substrate
concentration.
of
without
any
with
enzymes
at
different
temperatures
may
be
investigated
the
at
competitive
inhibitor
non-competitive
inhibitor
concentration
reaction
mixtures
in
water
baths
at
a
range
of
of
substrate
by
Figure 3.5.3
placing
no
starts
inhibitor
with
etar
activity
line
fo
Temperature
The
the
molecule
inhibitors
Enzyme-substrate
inhibited.
by
parts
non-competitive
but
its
with
so
0,0.
desylatac-emy zne
The
combine
active
produced
origin,
noitcaer
other
be
3.5.3.
the
Other
would
of
oxygen
the
there
temperatures.
This graph shows the effect
The
of a competitive inhibitor and a non-
substrate
and
enzyme
solutions
are
equilibrated
at
the
temperatures
used,
competitive inhibitor at increasing
then
mixed
together
and
kept
at
each
of
those
temperatures
over
the
range
substrate concentrations
chosen
(0 °C
to
70 °C
in
this
example).
The
results
of
such
an
investigation
6
protease
hydrolysis
of
milk
protein
are
shown
in
the
table
below
.
1
on
s/0001
−1
Temperature/°C
Time for
cloudiness
Rate of
reaction
×
1000/s
5
4
×
noitcaer
to disappear/s
no
0.0
1400
etar
10
reaction
2
fo
0
3
0.7
1
0
15
960
0
1.0
10
20
30
40
50
60
70
80
temperature/°C
20
650
1.5
25
480
2.
1
30
360
2.8
35
240
4.2
40
185
5.4
Figure 3.5.4
This graph shows the effect
of increasing temperature on the rate of
an enzyme-catalysed reaction
Summary questions
1
Explain
of
50
440
2.3
55
850
1.2
a
State
for
no
reaction
0.0
70
no
reaction
0.0
is
meant
by
terms:
each
range,
intermediate values
2
60
what
the following
the
the
limiting factor
reaction
substrate
when
the
concentration
–3
was
0.4 mol dm
evidence for
b
These
results
are
plotted
on
a
graph
(see
Figure
State
the
. Give
your
the
answer.
limiting factor
when
3.5.4).
the
substrate
concentration
−1
The
rate
of
reaction
increases
up
to
a
maximum
rate
of
5.4
×
1000 s
at
was
the
optimum
the
rate
temperature
of
40 °C.
At
temperatures
above
the
at
its
maximum
in
the
optimum
investigation.
decreases
steeply
and
there
is
no
activity
at
60 °C.
3
The
rate
increase
increases
in
frequently
as
kinetic
with
increased
energy
enzymes.
and
temperature
molecules
However
,
as
of
the
means
that
substrate
there
collide
temperature
is
an
and
molecules
vibrate
and
bonds
stabilising
the
tertiary
to
break.
At
the
optimum
temperature
the
number
of
of
is
at
enzyme
its
maximum,
molecules
but
become
beyond
that
temperature
non-functional
as
they
what
will
60 °C
all
the
enzymes
are
happen
to
the
reaction
more
i
mixtures
0 °C
to
if
30 °C;
and
70 °C
to
30 °C.
In
each
case
denature.
explain
At
the
successful
ii
more
at
35 °C
structure
transferred from:
collisions
reaction
65 °C.
Predict
following
begin
rate
temperatures:
the
4
enzyme
the
following
more
increases
Predict
your
answer.
denatured.
57
3.6
Factors
influencing
Learning outcomes
On
completion
should
be
able
of
this
Enzyme
section,
describe
enzyme

describe
pH
on
explain
the
on
and
the
effect
concentration
enzyme
of
of
activity
explain
enzyme
concentration
From
your
effect
of
understanding
increasing
the
the
effect
number
investigated
rates
of
reactions.
increased
of
collision
theory
you
can
probably
predict
the
of
Figure
by
concentration
of
there
can
shows
are
more
successful
making
reaction
3.6.1
If
of
enzyme
the
collisions
dilutions
be
enzyme
on
the
rate
of
determined
the
as
molecules
of
per
unit
catalase
on
page
there
enzyme-
time.
extract
This
and
will
can
the
be
an
be
initial
54.
results.
activity.
As
the
concentration
increases.
This
The
assumes
limiting
fo
etar
desylatac
-emyzne
noitcaer
concentration
rate
that
is
is
at
in
of
enzyme
directly
each
excess
increases
concentration
so
so
proportional
that
the
to
of
substrate
rate
the
of
reaction
enzyme
enzyme
the
concentration.
substrate
concentration
is
not
a
factor
.
pH
Reaction
mixtures
constant
pH.
possible
to
enzymes
Figure 3.6.1
(2)
to:
and
increasing
activity
you
catalysed

enzyme
may
These
make
were
be
prepared
solutions
buffer
are
solutions
investigated
at
using
known
over
special
as
buffer
various
different
solutions
ranges
solutions
ranges
of
to
of
pH.
maintain
and
it
a
is
Three
pH:
This graph shows the effect

pepsin

catalase

alkaline
of increasing enzyme concentration on the
rate of an enzyme-catalysed reaction
The
rates
phosphatase.
of
reaction
were
determined
and
are
shown
in
Figure
3.6.2.
alkaline
pepsin
catalase
phosphatase
100
etar
sa
60
40
etar
fo
fo
noitcaer
mumixam
egatnecrep
desylatac-emyzne
80
20
0
1
2
3
4
5
6
7
8
9
10
pH
Figure 3.6.2
Look
58
carefully

each

as
a
This graph shows the activity of three enzymes at different values of pH
at
enzyme
pH
Figure
is
increases
maximum
3.6.2
active
the
and
over
a
activity
follow
range
of
of
each
these
descriptions:
pH
enzyme
increases
until
it
reaches
Module

maximum

at

over
activity
occurs
at
the
optimum
pH
for
each
1
Cell
and
a
of
pH
certain
above
range
the
of
optimum
pH
there
is
pH
no
the
activity
is
pH
the
the
measurement
enzyme
shape.
The
amino
acids
some
of
longer
The
At
is
in
the
is
and
bone
site.
an
values
are
pH
of
in
tissue;
if
as
As
an
activity.
pH
at
enzyme
is
enzyme
blood,
it
the
and
not
lose
is
not
the
the
R-groups
concentration
their
simple
one
pH
linear
unit
scale. A
(e.g.
pH
7
.0
optimum
to
correct
become
a
of
of
the
changes
pH
8.0)
represents
concentration
of
a
change
hydrogen
in
ions
of
×10.
less
shape,
are
no
pH.
to
is
the
pH
between
of
where
1.0
with
with
a
a
pH
it
and
cytoplasm
body
places
very
of
pH
the
has
sites
close
pH
the
of
enters
ion
values
usually
site
At
between
active
enzymes
parts
is
active
hydrogen
the
where
in
the
these
enzyme
active
this
the
the
the
pH
concentration.
interactions
of
stomach
is
as
and
denatured
the
by
ion
break
intracellular
such
active
determined
phosphatase
optimum,
most
active
certain
active
Alkaline
is
its
hydrogen
interactions
optimum
Catalase
as
in
active
Pepsin
at
shape
these
effective.
is
of
foc us
decreases
change
pH
biology
enzyme
S tudy
values
molecular
is
high
about
pH
lower
works.
2.0.
7.0.
such
than
its
active.
Control variables
Buffer
etc.
solutions
As
and
it
other
we
is
have
therefore
factors,
pH
you
are
constant
factors
constant
about
as
Y
ou
in
that
are
that
to
is
each
are
do
to
this
and
that
keep
inuences
by
you
a
during
for
an
If
be
a
pH,
long
when
pH
as
are
to
the
other
any
7.0,
of
the
will
enzyme
keep
the
lasts.
which
three
valid
8.5,
S tudy
foc us
enzyme
reaction
but
pH
enzymes
investigating
and
investigating
the
draw
for
that
investigation
you
pH
activity
concentration
solution
as
e.g.
the
suitable
then
able
of
constant
buffer
activity,
not
pH
nding
variables .
will
are
the
mixture
enzyme
values
inuences
substrate
using
changed
control
you
certain
factor
reaction
not
called
factor
give
a
temperature,
can
otherwise
the
pH
investigating
constant
V
ariables
used
important
such
concentration.
that
are
seen
are
one
of
must
kept
the
be
kept
conclusions
You
could
be
asked
enzymes
with
you
also
may
enzymes
Do
not
about
the
covered
be
which
panic
in
questions
which
–
asked
you
the
do
of
about
are familiar;
about
not
other
recognise.
question
principles
this
you
will
be
enzymes
chapter.
investigating.
Summary questions
1
Predict
shown
what
on
becomes
2
Use
the
will
Figure
a
happen
3.6.
1
if
at
the
higher
enzyme
substrate
concentrations
concentration
is
not
than
in
those
excess
and
limiting factor.
information
in
Figure
Enzyme
3.6.2
to
Range of
which
complete
pH
this
table.
range over
enzyme
is
Optimum
pH
active
pepsin
catalase
alkaline
phosphatase
3
Explain
4
Suggest
how
mixture
even
5
State
why
the
a
buffer
you
might
though
control
temperature
solution
on
a
is
check
buffer
variables for
enzyme
used
that
when
the
solution
an
investigating
pH
does
not
has
been
added.
investigation
into
enzyme
change
the
in
effect
a
activity.
reaction
of
activity.
59
3.7
Practice
exam-style
questions:
Enzymes
These
two
complex
multiple-choice
type
that
information very
some
notes
to
we
questions
introduced
carefully.
help
you
It
is
a
analyse
on
are
of
page
good
these
the
46.
idea
to
types
more
Read
This question
the
write
of
hydrolyses
(Remember
questions.
is
a form of
that does
1
A
metabolic
pathway
consists
of
several
which
the
product
of
the first
about the
glycogen
of
the
second
and
reaction
is
of
a
metabolic
be
so forth. This
is
not
X
What
of
be
the
1
enzyme
effect
enzyme
2
reducing
specific for
→
of
adding
1
enzyme
2
substance Y
would
increase
3
substance
would
no
4
enzyme
5
substance
Z
and
and
Z
sugar
would
be
would
at the
is
not
B
1
4;
B
2
5; C
end
is the
2
because
starch
correct
a
competitive
down
the
rate
inhibitor
at
which
a
competitive
3
A
longer
P
concentration
reaction Y
to
Z. This
be
student
2,
3
and
questions
Q
investigated
protease
– from
a
– from
– from
The
produced
enzyme
so
4
1,
inhibitors
occupy
destroying
is
not
2
page
increase
B
2
is
the
A
them,
3
the
so
is
slowed
57),
as
it
then
is
correct
student
not
not
are
1
denatured. This
enzyme
(see
and
added,
enzyme
will
2
at
a
5;
D
5
slower
only.
then
sites
the
of
incorrect
down
(K
2
by
the
at
the
some
5.
prokaryote
a
the
which
effect
that
prokaryote
lives
that
of
in
lives
a
mammal
results
of
the
that
lives
in
investigation
If
the
the
of Y
rate
test-tubes
1
starch
in
glucose
3
glycogen
the
4
starch
5
sucrose
in
this
table.
enzymes/
maximum
Q
rate
R
0
5
0
35
10
10
0
60
25
enzyme
activity
20
8
100
35
30
15
70
48
40
30
35
95
50
45
18
35
60
65
0
0
70
100
0
0
90
40
0
0
of
inhibitor
would
by
enzyme
2.
with
solutions
amylase
and
that
the
Make
amylase
plot
See
multiple
and
at
scale
used
the
do
not
axis for
increase
temperature
page
lines
53 for
on
a
guidance
about
this
and
how
graph.
foc us
amylase
40 °C for
30
minutes.
examiners
sugar
be
detected
do
not
want
to
give
the
units
in
a
In
question
reducing
you
sucrase
When
kept
temperatures
sure
sucrase
and
and
foc us
S tudy
(possibly
because
they
involve
too
much
after
description)
they
will
call
them
arbitrary units. You
may
minutes?
abbreviate
A
1,
3
and
4
and
5;
B
1,
2
and
3; C
1,
4
and
5;
D
them
4
to
‘au’
in
1,
gures from
60
tropics.
given
20
correctly.
would
on
the Arctic
0
S tudy
and
2
tubes
try
springs
0
evenly.
30
can
of
Notice
which
you
temperature
hot
are
Activity of
P
without
competitive
usual
Contents
were
is
enzymes:
slows
activity
because
and
Test-tube
test-tubes
amylase
and U)
as follows:
The
and
rate
answer.
prepared
is
the
enzymes
concentration
used
this
catalyses
affect
leaves
the
glucose
incorrect. Competitive
active
is
enzyme
be formed
inhibited
is
an
answer.
percentage of
If
has
(glucose), there
Z
denatured
in
structured
Temperature/°C
A
glycogen.
amylopectin which
substrate
specific for
sucrose.
some
yourself.
R
1
are
for
three
be
in
2
2?
would
also
pathway:
→ Y
would
inhibitor
similar to
break down the
enzymes. Amylase
and
an
Here
enzyme
is very
starch
the
not
example
in
starch.) Although test-tube
present. Sucrase
substrate
specificity of
bonds
reactions
will
in
is
glycosidic
(K
and U)
your
graph.
your
answers
when
quoting
to
Module
a
Draw
a
graph
of
the
results
of
the
c
student’s
Explain
b
Describe
the
effect
of
temperature
on
and
in
pH
Cell
and
this
and
molecular
temperature
are
biology
kept
investigation.
enzymes,
5
P, Q
why
constant
investigation.
1
Enzyme
inhibitors
may
be
competitive
or
R.
non-competitive.
c
Explain
the
d
Suggest
effect
of
temperature
on
enzyme
R.
Make
how
function
4
Succinate
at
enzymes,
such
high
It
as
P,
are
able
diagrams
to
show
how:
to
i
competitive
inhibitors,
ii
non-competitive
and
temperatures.
dehydrogenase
mitochondria.
such
is
catalyses
a
an
enzyme found
reaction
that
inside
occurs
inhibitors
interact
with
enzyme
molecules.
in
6
Acetylcholine
is
a
chemical
transmitter
substance
respiration:
released
succinate
nerve
cells
at
synapses.
→
cells
breaks
foc us
in
Names of
You
may
to
succinate
a
down
synapse
contraction
biochemicals
see
conduct
impulses
written
as
succinic
acid
as fumaric
acid. At
the
pH
of
the
cell
ionise
to form
anions
ions
with
(negatively
inhibit
a
–COO
names
group)
with
the
not
as
sufx
acids
–ate
with
to
which
a
substance that
structure very
has
similar to that of
a
a
series of
to
small volume of
succinate. A
malonate
succinate
solution was
each test-tube. These tubes were
25 °C with test-tubes of
solution. The
and the
student
enzyme
initial
rate of
at
procedure
are
does
not
paralysis
or
and
remain
muscle
death.
organo-phosphates
enzyme
at
synapses
are
in
insecticides
insects
have
a
and
structure very
how
organo-phosphates
carbamates
with
its
the
and
do
not.
enzyme
organo-phosphates
acetylcholinesterase
to
activity.
Suggest
why
these
insecticides
are
health
hazards
environmental
hazards
if
not
used
carefully.
added
equilibrated
The
enzyme
sucrase
catalyses
the
hydrolysis
of
the
at
glycosidic
bond
in
sucrose.
A
investigated
succinate dehydrogenase
solution was
results
to
it
impulses
pH
added to
each tube
reaction determined. The
repeated the
malonate. The
a
that
student
6
to
lead
acetylcholine;
inhibit
and
6.5. A
can
animals. Carbamates
Explain
molecular
concentrations of
so
continuous
this.
b
prepared
and
this
interact
is
to
that
–COOH. They
show
a
Malonate
cells
enzyme
charged
similar
given
muscle
the
these
other
are
and
is
and
that
biochemicals
acetylcholine
causing
Carbamates
fumarate
stimulates
fumarate
contract. Acetylcholinesterase
S tudy
It
dehydrogenase
nerve
succinate
by
but without
shown
using
student
concentration
sucrase
at
Rate of
units
effect
on
the
of
increasing
rate
of
the
activity
of
40 °C.
3
test-tubes
different
succinate/arbitrary
the
sucrose
in the table.
Ten
Concentration of
of
were
set
up
concentrations
each
of
a
containing
sucrose
5
cm
of
solution. The
reaction/arbitrary
test-tubes
ten
were
placed
minutes. A flask
in
a
water
containing
a
bath
at
sucrase
40 °C for
solution
units
was
With
also
put
into
the
water
bath.
Without
3
malonate
malonate
After
ten
added
0
0
5
11
at
1
cm
the
added
the
sucrase
reaction
solution
mixtures
was
were
a further
water
to
each
was
ten
minutes. After
boiled.
Benedict’s
test-tube. The
time
ten
solution
taken for
a
18
colour
15
16
21
20
20
22
rates
a
change
of
was
enzyme
State
the
recorded
22
23
b
Explain
i
30
23
23
35
23
23
was
independent,
why
kept
and
used
to
calculate
activity.
control variables
25
of
test-tube. The
40 °C for
minutes,
12
was
10
each
0
kept
5
minutes,
to
the
at
in
dependent,
this
temperature
40 °C;
ii
derived
and
investigation.
why
it
of
the
was
water
raised
to
bath:
boiling
point.
a
Plot
b
Use
the
results
your
graph
malonate
on
on
to
the
a
c
graph.
explain
reaction
the
Sketch
a
results
and
graph
substrate
effect
catalysed
enzyme,
of
by
to
show
explain
the
the
student’s
effect
concentration
on
of
the
predicted
increasing
activity
of
the
sucrase.
succinate
dehydrogenase.
61
2
Genetics, variation
1.
1
Nucleic
of
this
section,
page
3,

be
state
able
that
polymers

list
the
nucleic
of
acids
nucleotides
components
a
acids
you
need
were
to
listed
know
as
one
about.
of
the
There
four
are
groups
two
of
nucleic
biological
acids:

deoxyribonucleic

ribonucleic
simple
of
diagram
acid
(DNA)
are
of
acid
These
polymers
which
are
stable
draw
that
to:
nucleotides

nucleic
you
molecules
should
selection
Polynucleotides
On
completion
natural
acids
Learning outcomes
On
and
are
shown
molecule
(RNA).
built
in
up
from
simplified
that
is
a
monomers
form
long-term
in
known
Figure
store
of
1.1.1.
genetic
as
nucleotides
DNA
is
a
large,
information.
There
a
are
three
types
of
RNA
that
are
used
for
retrieving
information
from
nucleotide
DNA

recognise
the
and
using
it
to
synthesise
polypeptides.
The
three
forms
of
RNA
structural formulae
are:
of
ribose,
deoxyribose,
pyrimidines

describe
and
and
the
RNA
structure
and
signicance
discuss
of
purines,

messenger

ribosomal

transfer
the
of
the
RNA
nucleotide
and
bonds.
and
not
(rRNA)
(tRNA).
is
composed
of
a
pentose
(5-carbon)
one
to
Each
the
of
make
five
bond
pentose
nitrogen-containing
polynucleotides
forms
sugar
of
by
between
the
phosphate
the
the
bases.
Nucleotides
formation
phosphate
of
are
the
structure
of
group
of
one
DNA
5’
structure
of
5’
O
HOCH
OH
2
proteins. The
OH
2
4’
4’
1’
1’
pentose
H
monomers
of
DNA
are
H
H
H
the
monomers
of
H
nucleotides;
proteins
are
3’
amino
H
H
sugars
H
2’
OH
3’
OH
2’
OH
H
acids.
ribose
deoxyribose
O
P
HO
phosphate
O
O
phosphate
H
H
O
base
N
H
C
C
N
C
N
N
N
C
C
purine
C
C
H
C
C
N
N
H
H
H
C
N
N
bases
N
2
H
H
deoxyribose
sugar
adenine
Figure 1.1.1
(A)
guanine
(G)
A simple diagram of a
nucleotide. Different shapes are used to
O
O
O
show the five different bases.
H
H
H
CH
C
C
C
N
C
C
3
C
C
N
C
CH
HN
C
C
N
O
S tudy
H
O
H
O
pyrimidine
CH
N
foc us
H
N
H
H
bases
In
RNA
‘U
cytosine
replaces T’.
Remember
this
as
you
work
next few
thymine,
62
pages.
RNA
has
DNA
uracil.
thymine
(T)
uracil
(U)
through
Figure 1.1.2
the
(C)
has
joined
phosphodiester
foc us
confuse
the
a
next.
HOCH
with
sugar
,
them.
together
Do
RNA
differences
group
S tudy
(mRNA)
DNA
Each
between
RNA
nucleotides
The structural formulae of the components of nucleic acids
nucleotide
Module
The

composition
Ribose
is
the
of
DNA
pentose
and
RNA
sugar
in
is
2
Genetics,
different.
RNA
–
at
variation
carbon
2
there
is
an
hydroxyl
is
double
stranded
Deoxyribose
is
the
pentose
sugar
in
DNA
–
at
carbon
2
a
replaces
the
hydroxyl
group
of
in
some
viruses
DNA
has
RNA
has
the
the
bases
bases
adenine,
guanine,
adenine,
that
have
DNA. Once
inside
ribose.
a

everywhere
hydrogen
single-stranded

selection
(–OH).
except

natural
Did you know?
DNA
group
and
cytosine
guanine,
and
cytosine
and
thymine
host
cell
replicated
this
viral
to form
DNA
is
double
usually
stranded
DNA.
uracil
DNA
carbon
atom
3
C
A
molecule
that
are
of
DNA
bonded
phosphates
projecting
opposite
is
a
double
together
make
up
inwards
the
and
by
helix
hydrogen
‘backbone’
forming
consisting
bonds.
of
each
hydrogen
of
The
two
polynucleotides
deoxyribose
polynucleotide
bonds
with
the
sugars
with
bases
the
of
ribose
and
phosphate
bases
A
the
polynucleotide.
G
guanine
The
only
nitrogenous
pairs
that
bases
fit
are
complementary
between
the
in
size
sugar–phosphate
and
shape
‘backbones’
so
that
are
the
A–T
and
U
C–G.
The
‘backbones’
are
arranged
so
that
the
orientation
is
in
opposite
carbon
directions
–
sugars
arranged
are
upwards
to
5'
the
on
the
direction
to
the
are
with
other
on
polynucleotide
angles
strands
one
so
carbon
that
side
assumes
antiparallel .
and
a
3
the
a
pointing
Figure
5'
to
3'
are
direction
shape
as
1.1.3
downwards
polynucleotides
helical
sugar–phosphate
In
the
on
base
you
on
can
one
arranged
the
are
side
in
other
.
pairs
see
a
at
Figure 1.1.4
Simplified diagram of a small
section of RNA
right
‘backbone’.
S tudy
5′
carbon
atom
and
atom
5
3′
foc us
are
pronounced
‘5
prime’
3
and
carbon
5
uracil
and
3'
Each
not
atom
the
‘3
prime’
and
are
used
to
C
G
identify
deoxyribose
phosphate
and
T
the
RNA.
polynucleotides
Note
polynucleotide
A
that
in
in
DNA
one
DNA
is
5′
to
3′
and
cytosine
the
C
opposite
is
3′
to
5′
G
guanine
T
A
carbon
atom
3
carbon
atom
5
adenine
Figure 1.1.3
Structure of a small region of DNA
Summary questions
1
Suggest
and
why
state
the
DNA
and
RNA
are
called
structural features
that
nucleic
they
acids
have
5
in
Name
simple
3
State
and
would
the ve
monomers
labelled
the
following
DNA
diagrams
structural
pairs:
purine;
DNA
show
differences
ribose
DNA
of
to
and
and
and
RNA
their
make
6
structure.
between
deoxyribose;
RNA;
and
each
of
the
7
is
an
organism
in
the
to nd?
ratio
necessarily
in full
DNA;
b
constant for
was found
percentages
expect
why
not
Explain
1 : 1
and
you
Explain
but
pyrimidine
polynucleotide
of
thymine. What
common.
2
The
why:
the
each
a
of
Explain
of A : G
the
the
ratio
the
and
same
ratio
of A
species
contain
your
three
24%
bases
answers.
of C : T
in
is
1 : 1
in
DNA,
RNA.
of A
+ T : C
but
to
other
+ G : C
+ G
varies
in
+ T
is
DNA
between
always
is
species.
polypeptide.
8
4
Suggest
why
DNA
is far
more
stable
than
RNA.
Make
of
a
DNA
for
table
and
to
compare
RNA.
Do
the
structure
not forget
to
and functions
include
a
column
the features.
63
1.2
DNA
replication
Learning outcomes
Templates
DNA
On
completion
of
this
section,
is
be
able
store
of
base
genetic
pairing
information
and
is
passed
on
to
new
cells
in
you
growth
should
a
and
and
to
new
generations
of
organisms
in
asexual
and
sexual
to:
reproduction.

explain
the
signicance
of
base
The
pairing
in
double
polynucleotide
polynucleotide

state the
signicance of
in
describe
the
process
conservative
means
of
within
semi-
replication
of
already
DNA.
DNA
cytosine
we
always
form
pulled
2 m.
out
it
in
it
your
all
the
would
Multiply
cells
that
cell
that
DNA from
extend for
by
body
would
template
a
copy
the
and
extend
it
to
number
is
a
about
of
estimated
the
sun
the
are
hydrogen
pairs
is
bonds,
which
enough
to
be
that
with
is
for
ideal
for
making
made
by
a
replication
new
matching
in
of
with
always
bases.
by
the
two
collectively
one.
because
The
nucleotide
when
a
pairs
sequence
with
with
polynucleotide
As
this
happens,
phosphodiester
template
each
term
bases
strand
are
are
these
to
against
the
held
double-stranded
bases
are
a
newly
and
assembled
the
This
but
bases
means
together
together
DNA,
and
and
bases
give
bonds
held
of
thymine
polynucleotide.
polynucleotides
stabilise
has
Nucleotides
existing
polynucleotide
the
broken
guanine.
together
each
and
polynucleotide
adenine
an
sequence
bonds
bonds
Each
along
joined
nucleotides
covalent
one.
together
nucleotides
Did you know?
you
a
know
complementary
human
that
existing
assembled
If
as
DNA
an

acts
hydrogen
template
bonding
structure
DNA
that
by
by
hydrogen
are
weak
needed.
and
CH
back
70
times!
H
3

O
N


N
H
N
N
N
H
N



N
O
thymine
adenine

H


H
O
N
N



N
N
H
N
N

O
N
Link
N
H


H
Look
back
to
information
page
on
4 for
more
hydrogen
bonds.
Figure 1.2.1
There are two hydrogen bonds between adenine (A) and thymine (T) and
three between cytosine (C) and guanine (G) in DNA
Before
S tudy
replication
happens
known
Why
DNA
semi-conservative?
molecule
polynucleotide
template
and
consists
that
one
conserved
molecule
of
as
DNA
acted
‘old’
half
–
Each
of
newly
polynucleotide. The
been
can
occur
,
nucleotides
need
to
be
synthesised.
This
foc us
one
as
‘old’
the
strand
hence
as
the
cytoplasm
and
deoxynucleoside
uses
energy
to
form
activated
nucleotides
triphosphates.
new
synthesised
the
in
new
has
Replication
same,
page
ensures
although
128).
(1929–)
the
sequence
of
occasionally
that
mistakes
occur
Research
in
1958
conservative
replication
or
Matthew
that
dispersive
involved
synthesised
by
showed
strands;
as
Meselsohn
replication
was
producing
dispersive
base
new
DNA
give
always
rise
(1930–)
was
proposed
pairs
to
at
and
remains
the
time.
involved
of
Frank
Stahl
not
Conservative
two
newly
making
DNA
semi-conservative.
composed
64
of
new
sections
alternating
from
one
strand
the
mutations
semi-conservative,
composed
replication
to
to
the
other
.
(see
Module
Step
The
1.
DNA
enzyme
helicase
Step
2.
separates
Each
assemble
Step
3.
DNA
and
a
travels
two
acts
both
the
new,
and
along the
between
the
DNA
polynucleotide
as
a
template.
catalyses the
elongating
bond
carbon
bonds
unwinds
base
and
strands of
Free
pairs
the
Genetics,
variation
and
natural
selection
break.
enzyme
DNA.
nucleotides
strands.
polymerase
to
covalent
nucleotide
hydrogen
the
strand
against
nucleotide
off
unwinds;
topoisomerase
2
is formed
3
of
template
phosphate
strand
is
assembled
in
a
5'
groups
strand
is
assembled
in
one
the
between
existing
strands
to
3'
attachment
strand. Two
in
a
the
3'
to
piece,
but
the
a
5'
break
phosphate
strand.
direction. This
of
phosphates
DNA
of
direction. The
means
other
is
the
polymerase
that
new
one
assembled
in
sections.
base
Step
4.
base
pairs
DNA
polymerase
are
cut
out
checks the
and
sequence;
any
pairs
incorrect
replaced.
sugar–
phosphate
backbone
Step
5.
Hydrogen
strands;
molecules
Figure 1.2.2
bonds form
topoisomerase
into
two
between
catalyses the
double
the
polynucleotide
winding
up
of
new
DNA
helices.
thymine
adenine
guanine
cytosine
Figure 1.2.3
Semi-conservative replication of DNA
A small part of DNA to show
its double helix structure
Link
Research
animations
replication’
done
that
online,
try
and Question
of
‘DNA
once
Summary
2
on
page
you
have
question
6
74.
Summary questions
1
Make
2
Use
a ow
chart
diagrams
to
to
show
explain
the
what
stages
is
in
meant
replication.
by
the
term
template
in
DNA
replication.
3
Explain
4
State
5
In
why
what
their
replication
is
paper
structure
of
required
of
pairing
6
Find
in
out
explain
in
necessary.
a
cell
before
1953, James Watson
DNA
mechanism for
is
that
the
they
genetic
it
and
described
material’.
can
replicate.
Francis Crick
‘suggests
Explain
a
the
wrote
possible
that
the
copying
importance
of
base
replication.
about
how
the
their
work
of
results
semi-conservative
rather
Matthew
showed
than
Meselsohn
that
the
and
method
conservative
or
Frank
of
Stahl
replication
and
is
dispersive.
65
1.3
Protein
synthesis
Learning outcomes
Overview of
Ribosomes
On
completion
of
this
section,
be
able
assemble

state
that
DNA
code for
explain
bases
triplets
how
in
bases
amino
the
DNA
of
in
cells
acids
amino
sequence
codes for
structure
of
of
amino
acids
rate.
the
All
large
produce
decreases;
of
messenger
produce
pancreas
the
primary
synthesis
in
acids
the
into
polypeptides.
correct
sequence
The
come
in
instructions
the
form
for
of
to:
molecules

protein
you
assembling
should
(1)
some
the
insulin
of
which
of
in
amino
the
acids
are
single
when
lymphocytes
ribosomes
sequence
RNA
quantities
the
for
in
For
concentration
produce
cell
produced
proteins.
antibody
require
insulin
nucleus.
of
blood
molecules
mRNA
or
the
example,
in
the
glucose
at
molecules
antibody.
Some
cells
a
very
that
Protein
fast
specify
synthesis
a
involves
the
following:
polypeptide

use
the
genetic
sequences
of
sequences
in
sequences
of
code
bases
RNA
to
in
DNA
and
amino
convert
transcription

activation
in
of
molecules;
polypeptides.
of
DNA
to
produce
mRNA,
which
occurs
in
the
nucleus
into
into
acids


translation
ribosomes
amino
this
of
acids,
occurs
in
mRNA
either
free
to
in
which
the
form
the
involves
attaching
them
to
tRNA
cytoplasm
polypeptides,
cytosol
or
which
attached
to
occurs
on
endoplasmic
reticulum
S tudy

foc us
post-translational
the
Protein
shapes
molecules
that
are
have
very
dependent
Golgi
of
sequence
changes,
have
a
amino
different
acids.
the
shape
If
properly,
if
at
DNA
can
does
not
The
which
occurs
in
code
is
a
store
sequence
for
an
of
of
genetic
bases
amino
information
in
acid.
a
length
There
of
are
for
the
DNA
four
is
synthesis
a
bases
code.
in
of
polypeptides.
Each
DNA
triplet
(A,
T
,
C
of
and
bases
G)
so
all.
it
is
possible
DNA
is
copies
S tudy
proteins,
the
codes
function
some
the
protein
and
of
specic
on
Genetic
sequence
modification
body.
a
of
to
make
template
the
base
64
for
different
making
sequence
triplets.
messenger
from
the
RNA
nucleus
which
to
conveys
ribosomes
in
short-lived
the
foc us
cytoplasm.
Why
64
triplets? You
can
count
the
The
number
in
the
table
or
calculate
it
as
diagram
shows
polynucleotides
how
relate
to
the
sequences
the
sequence
of
in
the
bases
mRNA.
in
The
the
two
polynucleotide
3
4
(4
×
4
×
4).
along
which
template
the
coding
bases
S tudy
base
are four
code
bases
does
not
in
DNA. A
work
as
it
is
not
4
strand.
which
is
the
of
RNA
transcription;
As
you
same
can
as
nucleotides
assembled
complementary
the
coding
see
that
is
the
of
the
strand
mRNA
is
the
polynucleotide
has
produced
a
sequence
except
is
of
that
U
T
.
two
only
coding
A
T
G
T
A
C
G
G
C
T
T
A
C
G
T
T
A
G
T
A
C
A
T
G
C
C
G
A
A
T
G
C
A
A
T
C
A
U
G
U
A
C
G
G
C
U
U
A
C
G
U
U
A
G
strand
2
codes for
sequence
for
foc us
replaces
There
the
strand
=
enough,
16
amino
whereas
acids
a four
which
base
template
code
would
code for
too
many
strand
4
(4
=
256).
mRNA
amino
acid
met
ser
gly
leu
arg
stop
reading frame
Figure 1.3.1
Follow the sequence of bases in the two polynucleotide strands of DNA and
in the single mRNA polynucleotide for the beginning and end of a polypeptide
66
Module
2nd
A
2
Genetics,
variation
base
2nd
G
T
C
U
and
natural
selection
base
C
A
G
AAA
Phe
AGA
Ser
ATA
Tyr
ACA
Cys
UUU
Phe
UCU
Ser
UAU
Tyr
UGU
Cys
AAG
Phe
AGG
Ser
ATG
Ser
ACG
Cys
UUC
Phe
UCC
Ser
UAC
Ser
UGC
Cys
AAT
Leu
AGT
Ser
ATT
Stop
ACT
Stop
UUA
Leu
UCA
Ser
UAA
Stop
UGA
Stop
AAC
Leu
AGC
Ser
ATC
Stop
ACC
Trp
UUG
Leu
UCG
Ser
UAG
Stop
UGG
Trp
GAA
Leu
GGA
Pro
GTA
His
GCA
Arg
CUU
Leu
CCU
Pro
CAU
His
CGU
Arg
GAG
Leu
GGG
Pro
GTG
His
GCG
Arg
CUC
Leu
CCC
Pro
CAC
His
CGC
Arg
GAT
Leu
GGT
Pro
GTT
Gln
GCT
Arg
CUA
Leu
CCA
Pro
CAA
Gln
CGA
Arg
GAC
Leu
GGC
Pro
GTC
Gln
GCC
Arg
CUG
Leu
CCG
Pro
CAG
Gln
CGG
Arg
TAA
Ile
TGA
Thr
TTA
Asn
TCA
Ser
AUU
Ile
ACU
Thr
AAU
Asn
AGU
Ser
TAG
Ile
TGG
Thr
TTG
Asn
TCG
Ser
AUC
Ile
ACC
Thr
AAC
Asn
AGC
Ser
TAT
Ile
TGT
Thr
TTT
Lys
TCT
Arg
AUA
Ile
ACA
Thr
AAA
Lys
AGA
Arg
TAC
met
TGC
Thr
TTC
Lys
TCC
Arg
AUG
Met
ACG
Thr
AAG
Lys
AGG
Arg
CAA
Val
CGA
Ala
CTA
Asp
CCA
Gly
GUU
Val
GCU
Ala
GAU
Asp
GGU
Gly
CAG
Val
CGG
Ala
CTG
Asp
CCG
Gly
GUC
Val
GCC
Ala
GAC
Asp
GGC
Gly
CAT
Val
CGT
Ala
CTT
Glu
CCT
Gly
GUA
Val
GCA
Ala
GAA
Glu
GGA
Gly
CAC
Val
CGC
Ala
CTC
Glu
CCC
Gly
GUG
Val
GCG
Ala
GAG
Glu
GGG
Gly
A
U
G
C
esab
esab
ts1
ts1
T
A
C
G
Figure 1.3.2
These tables show the genetic dictionaries for DNA triplets and RNA codons. Amino acids are commonly known by their
three-letter abbreviations.
The
groups
of
three
bases
in
RNA
are
known
as
codons.
The
tables
above
S tudy
show
the
strand
genetic
and
RNA
dictionary
codons.
in
The
the
form
DNA
of
DNA
triplets
and
triplets
RNA
on
the
codons
form
the
You
genetic
code
that
specifies
each
of
the
amino
acids
during
foc us
template
do
not
need
to
learn
these
protein
triplets
and
codons,
but
expect
to
synthesis.
use
T
o
read
second,
acid
the
DNA
e.g.
C,
cysteine.
genetic
genetic
and
then
Now
dictionary.
find
The
dictionary,
the
the
third,
find
e.g.
the
G.
complementary
base
sequence
is
first
This
base
UGC
base,
triplet
e.g.
sequence
and
A,
codes
this
is
then
for
in
the
the
the
the
a
genetic
triplets
to
dictionary
codons
to
and
amino
convert
acids.
amino
mRNA
codon
S tudy
for
foc us
cysteine.
Take
In
reading
the
message
for
a
polypeptide
a
cell
needs
a
‘start’
triplet
care
‘triplets’
well.
The
triplet
code
for
methionine
(met)
on
the
template
strand
and
its
codon
is
AUG.
This
is
the
start
codon.
Methionine
removed
from
the
beginning
of
the
polypeptide
after
it
and
bases
use
of
the
terms
‘codons’. The
in
DNA
are
groups
of
called
is
triplets;
usually
your
is
three
T
AC
over
as
groups
of
three
bases
in
is
mRNA
are
known
as
codons.
produced.
Features of the
–
it
genetic

universal

it
codes
for
the
is
20
found

it
codes
for
the
sequence
code
in
all
amino
organisms
acids
of
found
amino
(with
in
acids
a
few
minor
variations)
Summary questions
proteins
that
form
the
primary
1
structure
of
Explain
must

a
sequence
why
of
three
nucleotide
bases
codes
for
an
amino

there
are
three
‘stop’

there
are
between
be
three
two
or four
one
and
six
codes
for
each
amino
acid
(met
has
Make
there
are
more
a
table
to
codes
codes
than
needed
so
the
genetic
code
is
called
a
genetic
dictionary

the
stop
gives
the
codes
for
the
20
amino
acids
plus
the
amino
acids:
and
serine,
glycine,
methionine.
the
of
(expect
bases
U
in
the
replaces
coding
strand
of
DNA
is
the
same
as
Write
out
the
RNA
sequence
of
complementary
bases
to
in
that
code for ADH
sequences
(see
page
and
oxytocin
13).
T)
the
in
that
the
4

DNA
codons
codes
sequence
mRNA
the
RNA
code
3
three
and
the following
valine,

show
a
phenylalanine,
degenerate
one
six)
for

not
bases.
one
template
has
code
and
codes
2
arg
genetic
bases
acid
or
and
the
polypeptides
template
strand
of
DNA
Biologists
talk
about
‘one
gene
is
one
polypeptide’.
you
understand
Suggest
what
mRNA.
by
this
phrase.
67
1.4
Protein
synthesis
Learning outcomes
Transcription
DNA
On
completion
should

be
dene

able
the
describe
as
of
this
section,
is
located
amino
acids
free
in
the
(see
page
to
term
how
transcription
DNA
is
transcribed
Transcription factors
bind
to
cytosol
31).
of
the
promoter
for
a
produce
large
through
the
on
this
see
Transcription factors
genes
during
as
a
cell
the
cells.
are
Ribosomes
situated
in
the
that
assemble
cytoplasm,
nuclear
of
has
It
endoplasmic
two
may
version
of
pores
many
to
the
and
copies
be
of
that
the
transcripts
are
of
each
only
The
of
in
The
one
either
all
cell
on
each
is
may
the
form
RER
genes
cannot
to
the
form
those
DNA
information
produced
to
gene,
one
polypeptide.
polypeptide.
provide
reticulum
able
need
loop
to
out
ribosomes
of
mRNA
by
transcription.
occurs
in
the
nucleus
of
eukaryotic
cells.
The
region
of
gene
to
be
transcribed
is
activated
by
transcription
factors
that
identify
sequence, for
page
‘switch
area
of
DNA
to
open
up.
Only
small
regions
of
DNA
on
a
123.
chromosome
are
the
bonds
activated
at
any
one
time.
T
o
access
the
template
strand,
on’
hydrogen
between
the
strands
must
break
and
the
double
helix
differentiation, for
information
on
this
as
in
replication.
see
The
page
only
quantities
result
process
uncoils
more
of
the
the
the
information
cell
functioning
code
DNA
as
Each
attached
to
T
ranscription
in front
or
chromosome.
the
known
nucleus
polypeptides
homologous
and
DNA
the
make
to:
Link
of
in
you
mRNA.
region
(2)
enzyme
RNA
polymerase
is
responsible
for
assembling
the
RNA
76.
nucleotides.
3′–5′
direction.
bonds.
S tudy
foc us
known
Termination factors
termination
signal
bind
region
Transcription factors
factors
are
specic
proteins
regions
of
to
and
that
The
The
as
The
RNA
the
enzyme
moves
nucleotides
polymerase
termination
template
assembled
when
which
it
by
forming
reaches
follows
a
strand
a
of
the
specicity
of
phosphodiester
to
be
Hydrogen
bases
are
in
of
bases
triplet.
unwinds
about
to
the
sequence
stop
chains
examples
in
in
corresponding
termination
DNA. They
the
DNA
DNA.
bind
are
stops
signal,
the
of
along
specific
to
areas
gene
transcribed.
bonds
the
the
two
break
in
between
the
polynucleotide
the
area
of
DNA
protein
corresponding
to
the
gene
to
be
molecules.
transcribed. This
is
catalysed
by
helicase.
One
polynucleotide
template for
mRNA.
the
Free
nucleus
exposed
S tudy
RNA
bases
nucleotides
are
here.
Each
ribose
nucleotide
sugar
has
of
two
of
the
in
and
energy
replication
phosphates
bond
to form
between
the
a
growing
chain
template
are
joined
phosphodiester
to form
the
loss
the
provide
a
(which
which
does
is
polynucleotide
catalysed
RNA
than
DNA
less
proof
reading
polymerase).
and
leaves
the
nucleus
becomes
nuclear
mRNA.
Figure 1.4.1
Transcription
pore
a
by
polymerase
transcript
phosphodiester
nucleotide
enzyme
through
68
by
mRNA. This
mRNA
the
the
in
the
three
RNA
the
on
with
a
–
phosphates. As
a
of
nucleotides
up
nucleotides
bonds
base,
as
not
together
shown
RNA
pair
acts
synthesis
polynucleotide.
foc us
The
The free
the
nuclear
pore
Module
The
end
process
of
transcription
is
an
mRNA
transcript.
Since
there
2
Genetics,
variation
ribosomes,
times.
These
the
mRNA
mRNA
polymerase
transcripts
travel
will
from
transcribe
the
the
nucleus,
gene
and
into
the
through
on
one
from
is
strand
one
DNA.
in
are
many
Along
polynucleotide,
chromosome
molecules
a
while
transcribed
respects
to
replication
chromosome,
other
from
genes
the
some
elsewhere
opposite
but
genes
on
only
are
occurs
They
transcribed
the
ribosomes
cluster
molecules
polynucleotide.
enzymes
should
know
the
similarities
and
differences
between
these
that
are
summarised
in
Features
topoisomerase
unwinds
helicase
hydrogen
breaks
within
the
strands
of
DNA
Replication
Transcription




2
1
act
as
broken
life
down
span
determined
mRNA
by
of
the
as
their
–
how
long
it
takes
their
to
decrease
by
a
half.
base
refers
nucleotides
foc us
templates
The
free
to form
DNA
polynucleotide
that
by
time.
table.
S tudy
number
used
same
(polysomes).
the
concentration
bonds
be
the
two
half-life
processes
are
and
is
at
together
polyribosomes
molecules
Y
ou
can
cytoplasm.
similar
of
foc us
nuclear
many
T
ranscription
selection
many
mRNA
pores
natural
are
S tudy
many
and
align

against
to
pairing
that
in
transcription
between
the
template

strand
in
DNA
and
the
newly formed
DNA
mRNA.
bases
of
the free
nucleotides
adenine,
guanine,
cytosine,
base
pairing
name
type
of
of
A–T
enzyme
involved
guanine,
cytosine,
and C–G
DNA
polynucleotide
adenine,
thymine
A–U
polymerase
RNA
DNA
uracil
and C–G
polymerase
S tudy
mRNA
foc us
produced
rRNA
quantity
a
of
DNA
involved
in
all
nucleus
the
DNA
in
the
only
nucleus
the
genes
active
DNA
that
at
of
the
is
are
the
also
some
tRNA
time
and
tRNA
produced
(see
by
permanent
(see
page
page
62)
are
transcription. There
70)
base
and
pairing
in
in
rRNA.
Summary questions
1
State
what
2
Draw
a ow
3
Suggest
4
Explain
a
short
of
5
the
of
per
1.4.
1
transcribed
not
to
before
show
polymerase
time,
cell
to
it
the
transcription
RNA
once
Figure
needs
chart
why
why
cell
period
DNA
Use
a
while
can
carry
stages
of
a
gene
travels
DNA
of
out
transcription.
transcription.
does
along
a
not
stop
region
polymerase
only
of
at
a
stop
DNA
travels
triplet.
many
along
a
times
in
region
cycle.
explain
why
only
one
polynucleotide
of
a
gene
is
both.
69
1.5
Protein
synthesis
T
ranscription
Learning outcomes
template.
On
completion
should
be
able
of
this
section,
the
to:
dene
the
terms
first
and
describe
into
a
how
to
mRNA
is
translated
polypeptide
explain
is
a
the
roles
pool
about
of
which
mRNA
Once
a
in
mRNA
is
the
a
or
copy
is
produced
of
the
cytoplasm
polypeptide.
‘identified’
acid
ribosomes
of
in
mRNA,
of
of
ten
not
For
‘labelled’
this
using
it
to
the
from
DNA
can
code
be
DNA
for
translated
happen,
same
a
amino
three
base
into
acids
molecules
do
not
have
bases,
they
are
attached
codes.
to
RNA
amino
of
have
the
the
that
do.
acids
twenty
ability
of
This
all
amino
to
process
20
types
acids
make
is
in
have
them
amino
the
to
from
acid
activation .
cytoplasm.
be
present
anything
In
in
else.
There
humans,
the
diet
Our
as
cells
we
are
tRNA
able
and
be
of
acids.
in
translation
do

molecule
sequence
amino
molecules

process
amino acid
Since
activation
the
amino
primary
have

is
Each
assembling
you
(3)
to
synthesise
the
other
ten
amino
acids.
Lysine
is
an
example
of
an
protein
amino
acid
we
cannot
make
and
which
must
be
in
the
diet.
synthesis.
Amino
acid
activation
Did you know?
Enzymes
Amino
acids
cannot
such
make,
are
as
lysine,
known
as
which
we
essential
acids
specific
the
amino acids
in
and
the
tRNA
in
tRNA
of
protein
important
as
RNA
molecule
attachment
stage
cytoplasm
transfer
an
for
molecules
this
have
it
a
active
each
amino
synthesis
after
have
molecules
is
type
acid
in
to
which
of
its
that
The
amino
tRNA
the
identified
shape
sites
(tRNA).
its
resembling
acid.
of
tRNA
a
specific
the
amino
recognise
Energy
molecule.
identity
by
accept
enzymes
is
This
amino
the
required
is
the
acid
for
only
is
molecule.
clover
leaf
with
the
following
regions:
Link

a
site
where
amino
acids
are
attached
–
always
with
the
base
sequence
–CCA
This
is
back
the
a
to
good
page
structure
point
12
to
of
an
at
which
remind
amino
to
look
yourself
acid.

two

a
‘loops’
of
nucleotides
formed
by
some
base
pairing
of
‘loop’
with
an
anticodon
–
the
three
bases
that
identify
the
amino
acid.
Figure
3'
1.5.1
shows
a
tRNA
molecule
with
the
methionine
anticodon
UAC.
glycine
A
amino
acid
C
attachment
C
site
5'
C
A
G
C
C
C
A
C
U
hydrogen
bonds
ATP
ATP
AMP
AMP
ATP
AMP
glycine
U
C
C
G
A
C
C
A
C
U
C
A
anticodon
Figure 1.5.1
A tRNA molecule
anticodon
Figure 1.5.2
synthetase
70
anticodon
anticodon
Amino acid activation by a type of enzyme known as an aminoacyl tRNA
Module
The
enzymes
constantly
activate
amino
acids
so
that
there
is
a
2
Genetics,
variation
to
take
part
in
A
and
acyl
that
there
units
of
is
can
a
large
begin.
ribosomes
ribosome
has
two

accepts
supply
mRNA
and
fits
sites
an
of
into
A
activated
combines
a
site
‘groove’
and
a
amino
with
P
the
acids,
large
between
the
the
and
process
small
two.
site
the
tRNA-amino
acid
sites. A
P for
them
P
As
site
you
Figure
holds
read
the
the
lengthening
account
below
A
site.
the
process
The
first
a
the
tRNA-methionine
codon
molecule
therefore
not
with
occupy
complex
remain
ribosome
the
enters
in
(AUG)
so
the
is
the
anticodon
site.
the
place.
moves
not
translation
stages
enzyme
peptidyl
an
transferase
enzyme
made
of
is
If,
A
site
When
that
by
complex
start
codon
then
the
the
UAC
chance,
it
tRNA
enters
and
bond forms
the
whole
will
pair
only
another
does
not
enters
complex
with
it
a
pair
the
A
and
site,
does
carrying
C
C
codes
A
site.
for
G
the
the
G
are
into
A
C
fits
empty
the
G
These
complex
an
and
G
AGC.
UCG
C
is
is
C
it
codon
G
with
tRNA-serine
exposing
U
pairs
a
site
G
so
second
P
U
that
and
the
the
ly
the
A
example,
occupy
g
t-RNA-amino
A
anticodon
to
ser
and
A
our
moves
Now
ribosome
that
both
sites
are
full
the
enzyme
peptidyl
transferase
ribosome
catalyses
the
formation
of
a
peptide
bond
between
the
moves
C -terminal
the
two
of
methionine
amino
acids
and
the
N-terminal
of
serine
to
join
along
the
ribosome
molecule
dipeptide
leaves
(met-ser)
anticodon
peptide
moves
the
CCC
bond
to
the
ribosome
occupies
occupies
forms
third
and
the
the
between
P
now
the
the
codon.
The
second
one
site.
A
empty
tRNA
A
dipeptide
site
and
first
with
and
the
the
another
glycine.
This
U
on
the
C
are
C
that
C
factors
C
elongation
G
requires
A
process
gly
ser
tRNA
carrying
A
elongation
mRNA
together
.
met
Now
ribosome.
for
a
stop
this,
G
reaches
anticodon
G
ribosome
an
G
the
with
G
until
tRNA
C
no
U
is
G
continues
There
A
process
codon.
U
This
so
ribosome
translation
stops
and
termination
factors
remove
the
mRNA
ribosome
molecule.
moves
along
m
e
se
r
tripeptide
g
ly
Dene
2
Make
3
Explain
the functions
mRNA,
tRNA
the following
a
table
to
terms:
compare
and
of
amino acid activation
tRNA
and
translation
mRNA.
the following
peptidyl
and
in
translation:
ribosome,
transferase.
U
A
actively
if
carrying
there
out
were
protein
no
lysine
in
a
human
synthesis.
translation
that
a
cell
provide.
mRNA
b
G
requirements for
G
the
G
of
C
list
G
must
a
U
Make
U
a
G
A
5
C
was
happen
C
that
would
C
cell
what
C
Suggest
G
A
4
mRNA
t
Summary questions
1
Explain
the
role
of
each
item
in
a
rRNA
protein.
C
In
serine
–
in
U
methionine
site.
to
sites.
complex
met
acid
P
1.5.3.
start
tRNA
and
amino-
is ne
Did you know?
Each
peptide
T
o
as A
It
site:
polypeptide.
follow
stands for
peptidyl.
of
ribozyme

foc us
sub-
The
A
P
and
know
translation
selection
translation.
Translation
Now
natural
ready
S tudy
supply
and
your
ribosome
list.
Figure 1.5.3
Translation
71
1.6
Genes
to
Learning outcomes
phenotypes
Chromatin
Eukaryotic
On
completion
of
this
section,
cells
microscope
should
be
able
describe
the
between
relationships
DNA,
chromatin
explain
the
nuclei
known
used
homologous
in
which
chromosome

discuss
the
and
links
is
you
not
and
Where
as
the
between
phenotype
of
can
can
see
often
clearly
see
with
that
the
the
light
appearance
that
is
is
active
The
less
the
stain
associated
tightly
and
areas
coiled
This
it
is
is
with
takes
stain
DNA
staining
being
darkly
histone
up
inactive
densely
DNA
more
areas
than
of
others.
proteins
more
that
are
is
of
to
form
deeply
not
and
being
euchromatin
transcribed.
chromosomes
an
Chromosomes
This
double
precise,
become
structures
tightly
the
visible
happens
two
to
after
as
consisting
make
sister
separate
they
two
have
of
two
sister
chromatids
structures
replicated,
molecules
chromatids .
are
so
of
nuclear
chromosomes
DNA
As
genetically
during
the
that
are
replication
is
very
identical.
foc us
The
chromosomes
metaphase
can nd
protocols for
by
searching
of
are
mitosis
clearly
(see
visible
page
81).
as
If
separate
they
are
structures
during
photographed
at
the
this
stage
extracting
the
the
image
can
be
sorted
to
match
the
chromosomes
into
homologous
term
pairs.
‘learn
DNA
this
some
heterochromatin .
more
packaged
online
you
Y
ou
DNA,
are
DNA
since
transcription.
is
division.
You
that
stain.
karyotype
organism.
S tudy
a
even
Homologous
proteins
nuclei
use
contain
chromatin.
is
terms
nuclei
The
and
chromosomes

if
to:
the

have
you
The
arrangement
of
chromosomes
into
pairs
is
a
karyotype.
The
genetics’.
chromosomes
the
centromere
The
Y
in
sex
each
is
pair
always
chromosomes,
chromosome
chromosomes
is
are
in
X
the
the
and
are
known
as
same
Y
,
homologous
same
are
with
size,
place
not
the
they
and
like
X
have
they
this
as
the
have
only
chromosome.
same
the
a
same
small
The
shape,
genes.
part
of
the
non-sex
autosomes
centromere
The
human
and
two
two
sex
genome
sex
has
about
chromosomes.
chromosomes.
20 000
The
Males
genes
and
chromosomes
have
22
pairs
of
22
are
pairs
of
autosomes
numbered
autosomes
1
and
to
an
22
X
and
and
a
X
Y
Figure 1.6.1
chromosome.
Genes
a
protein to
control
polypeptide
cell
it
will
through
Red
blood
b
cells
The
of
does
16.
of
about
the
haemoglobin
molecular
refer
to
genes
the
not
sickle
shows
a
form
cell
of
are
two
or
a
oxygen
anaemia
some
if
autosomes
is
as
to
be
to
involve
structure
happens
stem
cells
by
a
and
two
in
protein.
X
then
Golgi
added
to
bone
it
may
the
If
it
will
body
marrow.
with
Large
the
it
is
a
other
involve
and
in
pass
where
production
synthesis
translation,
used
make
combining
with
protein
the
or
After
structures.
exported
molecules
also
formed
in
tertiary
reticulum
sugar
may
acids
and
it
quaternary
from
faulty,
occur
transport
having
rearranged
the
is
on
polypeptides
then
faulty
is
page
on
different
proper
of
being
of
cut
insulin.
numbers
assemble
and
Diseases
the
if
they
are
of
is
of
of
into
that
they
faulty.
If
one
haemoglobin
produced
and
haemoglobin
thalassaemias.
polypeptides
phenotype
chromosomes.
production
haemoglobin
affected.
130)
the
are
the
molecule
genes,
the
either
severely
(see
human
consequences
72
of
molecules.
for
genes
amino
endoplasmic
polypeptides
haemoglobin
cytosol;
by
form
polypeptides
and
the
of
secondary
Modification
to
and
a
details
to
into
rough
polypeptides
page
pairs
phenotype
sequence
possibly
glycoprotein.
Link
the
folds
pass
the
modified,
structure
22
chromosomes.
DNA to
more
have
Homologous pair of
chromosomes: the human X chromosomes
For
Females
The
code
for
the
are
table
and
the
Module
Conditions
the
at
in
the
Himalayan
warm
phenotype
that
are
the
colour
the
of
direct
an
Siamese
rabbit
and
of
the
and
is
gene
between
expression
in
melanin
organism
result
interaction
of
inuence
of
temperatures
The
and
body
breed
Siamese
is
all
only
its
action
genes
and
genes.
features,
For
example,
tyrosinase
produced
(for
the
of
cats,
in
both
example,
the
is
environment
Genetics,
variation
and
natural
selection
in
inactivated
extremities.
internal
sickle
2
and
cell
(for
external
anaemia)
example,
the
cats).
Link
Gene
Chromosome
Polypeptide
Consequences of
location
affected
faulty
gene
Two
genes
enzymes
a
globin
16
a-globin
given
that
tyrosine
globin
11
b-globin
11
enzyme:
table
code for
in
and
the
amino
acids,
phenylalanine,
as
b-thalassaemia
shown
TYR
the
involved
a-thalassaemia
metabolising
b
in
are
tyrosinase
in
the
diagram.
albinism
(transmembrane
no
protein
melanin
in
the
skin
in
or
hair
melanocytes)
PAH
12
enzyme:
phenylketonuria
phenylalanine
(PKU)
hydroxylase
AR
X
testosterone
no
receptor
protein
receptor
complete
testosterone
insensitivity
INSR
19
insulin
receptor
no
receptor
(Donohue
syndrome
protein
Summary questions
1
Dene
the
terms
chromosome
syndrome)
relationship
protein
in
diet
2
Draw
a
digestion
in
a ow
named
use
3
that
phenylalanine
between
chart
gene
to
may
the
and
the
two.
show
how
inuence
Find
out
ability
hydroxylase
(You
information from
sections
about
inuence
when
explain
phenotype.
previous
occur
chromatin
the
gut
human
reactions
and
to
in
the
need
this
this
to
and
the
chapter.)
genes
that
the following features:
see
colour;
production
tyrosinase
of factor VIII for
(PAH)
phenylalanine
testosterone
blood
clotting;
receptor. What
do
DOPA
accummulates
these
tyrosinase
phenylpyruvic
4
acid
to
what
protein
in
may
common?
happen
molecules
after
Explain
why
insulin
receptor
developing
proteins
ner vous
have
translation.
5
damage
Outline
to
dopaquinone
causes
genes
enter
the Golgi
body
system
after
translation,
polypeptides
of
but
the
a
and
haemoglobin
b
do
melanin
mutations
in
genes
tyrosinase
cause
for
PAH
blocks
in
and
not.
metabolism,
6
so
reactions
do
not
Explain
of
Figure 1.6.2
the
effects
of
mutations
occur
the
genes:
i
TYR;
ii
PAH;
iii
AR;
The TYR and PAH genes code for enzymes that are involved in metabolising
iv
INSR
on
the
phenotype.
the amino acids phenylalanine and tyrosine
73
1.7
Practice
exam-style
Structure
All
the
questions
questions. You
that
in
this
can find
accompanies
this
section
more
are
short
practice
and
roles
answer
MCQs
on
questions:
of
a
Make
a
simple
the
book.
of
labelled
diagram
of
a
normal
Explain
why
in
and
DNA
there
are four
different
all the
containing
cycle of
DNA
a
medium
containing only
nitrogen. After one
isolated from these
both
isotopes of
cycle
bacteria
DNA. After
replication
in the
medium
a
containing
nucleotides
light
isotope,
half of the
DNA was
similar to that
not five.
produced
c
isotope of
nucleotide.
the
DNA
light
replication
further
b
acids
bacteria were transferred to
the CD
had
1
nucleic
State THREE
ways
in
which
mRNA
in the first
cycle of
replication
and the
rest
differs from
had only the
light
isotope.
DNA.
a
Which
part
of
a
nucleotide
contains
the
element
nitrogen?
2
In
1958, the American
Meselsohn
their
and
a
heavy
In
the
The
many
1950s,
results,
Watson
replication
nitrogen
contained this
and
Francis Crick
Organism
a
bacteria. They
in
all the
Explain
table
grew
c
containing
Predict
would
DNA
the
below,
i
relative
provided
how
replication
isotope. Some of the
determined
the
b
results of
medium
so that
Erwin Chargaff
in
in
in
heavy
summarised
Matthew
published the
generations
isotope of
molecules
3
Frank Stahl
experiments on
bacteria for
researchers
quantities
of
evidence for
the
these
is
results
have
the
that
obtained
conservative;
the four
results
support
the
idea
ii
bases
structure
if
Meselsohn
and Stahl
replication
was:
dispersive.
in
of
DNA
DNA
in
different
proposed
organisms.
by James
1953.
Percentage of
Percentage of
Percentage of
Percentage of
adenine
thymine
guanine
cytosine
24.7
23.6
26.0
25.7
31.3
32.9
18.7
17
.
1
wheat
27
.3
27
.
1
22.7
22.8
octopus
33.2
31.6
17
.6
17
.6
sea
32.8
32.
1
17
.7
17
.3
chicken
28.0
28.4
22.0
21.6
human
29.3
30.0
20.7
20.0
Escherichia coli
that
semi-conservative.
(bacterium)
a
a
yeast
urchin
Explain
the
The
how
the
structure
next
table
of
data
in
the
shows Chargaff ’s
Organism
Percentage of
a
24.0
virus
b
State
how
c
Suggest
d
In
the
would
e
74
the
why
DNA
you
Explain
table
data for
the
the
data for
expect
the
to
the
arrangement
of
nucleotide
bases
in Watson
and Crick’s
model
of
the virus
of A
a virus.
Percentage of thymine
Percentage of
31.2
23.3
nucleotide
a fish,
contain
ratio
data for
adenine
extracted from
why
confirms
DNA.
is
bases
+ T
the virus
different from
28%
cytosine?
+ G : C
in
of
the
the
data for
Explain
your
differs from
all
contain
the
the
to
data for
other
the
cytosine
species.
organisms
in
the first
table.
organisms.
adenine. What
answer.
species
Percentage of
21.5
differ from
nucleotides
guanine
percentage
of
the
nucleotides
Module
4
Lysozyme
is
secretions
is
an
to
composed
folded
The
into
table
enzyme found
break
of
a
down
one
the
in
polypeptide
specific
tears
cell
tertiary
and
walls
of
of
130
other
b
bacteria.
amino
2
Genetics,
Outline
It
DNA
acids
how
leads
receptor
structure.
c
shows:
a
to
variation
sequence
the
of
why
surface,
but
the
the
natural
selection
nucleotides
production
glycoprotein for
Suggest
and
of
the
in
membrane
insulin.
receptor for
receptor for
insulin
is
on
testosterone
the
is
cell
in
the
nucleus.

the
sequence
lysozyme
of
three
amino
acids
in
the
human
polypeptide
S tudy

one
possible
mRNA
that
sequence
codes for
of
nucleotide
these
amino
bases for
acids.
Question
give
arg
foc us
the
cys
all
6b
the
asks for
details
it
says
that
glycoprotein. You
CGU
an
outline,
so
transcription
you
and
do
not
have
to
translation. Also
glu
notice
mRNA
of
UGC
the
membrane
should
refer
to
receptor
the Golgi
is
a
body
in
your
GAA
answer.
template
…
DNA
…
…
In Question
steroid
a
Copy
and
DNA
complete
triplets
on
the
the
diagram
template
to
show
Explain
why
the
human
is fat
a
different
gene for
sequence
of
need
to
know
that
testosterone
is
a
soluble.
strand.
lysozyme
The
diagram
triplets from
shows
the
part
of
the
process
of
protein
may
synthesis
have
you
the
7
b
and
6c
that
occurs
in
the
cytoplasm
of
eukaryotic
the
cells.
answer
you
Lysozyme
have
has
given
a very
in
a
specific
tertiary
structure.
cys
amino
c
Explain
how
the
DNA
in
the
gene for
acid
lysozyme
gly
determines
the
specific
tertiary
structure
of
cys
arg
glu
lysozyme.
5
a
State THREE
from
The
table
that
ways
in
which
transcription
differs
replication.
shows
inhibit
the
modes
replication
and
of
action
protein
of
several
A
drugs
synthesis.
C
C
C
Drug
Mode of
C
action
E
U
G
A
aphidicolin
inhibits
DNA
A
A
C
direction
C
C
G
U
polymerase
B
C
ciprooxacin
inhibits
which
R
rifampicin
the
enzyme
unwinds
inhibits
RNA
D
topoisomerase
DNA
a
Name
b
State
the
the
types
terms
of
RNA
used
labelled A,
to
describe
of
B
the
ribosome
and C.
groups
of
polymerase
nucleotide
bases
at
D
and
E.
(rifampin)
c
T
tetracycline
prevents
to
the A
the
site
attachment
of
of
Explain
t-RNA
ribosomes
correct
the
protein.
to
b
Explain
on
the
effects
replication;
ii
that:
drugs
R
i
drugs A
and T
and C
have
on
have
d
protein
how
the
help
you
amino
acids
sequence
(You
with
in
may
your
refer
that
are
arranged
primary
to
the
into
structure
diagram
of
above
answer.)
Describe THREE features
molecule
become
the
of
a
not found
polypeptide
in
a
DNA
molecule.
synthesis.
c
Drugs
these
R
and T
drugs
only
do
not
affect
bacteria. Suggest
affect
eukaryotic
why
S tudy
Question
6
A
length
of
DNA
with
a
specific
nucleotide
the
code for
the formation
of
the
is
of
a
a
the
hormone
glycoprotein found
cells
in
State
the
the
codes for
liver,
name
the
insulin. The
in
the
muscles
given
to
receptor
cell
the
receptor
surface
and fat
asks
the
you
right
to
explain
sequence,
how
so
the
this
amino
answer
acids
are
needs
of
of
translation.
protein
membrane
storage
length
in
receptor
details
protein for
7c
sequence
arranged
carries
foc us
cells.
tissue.
DNA
that
protein.
75
2
Genetics, variation
2.
1
Mitosis
of
this
section,
started
life
be
able
distinguish
cell

between
nuclear
and
division
state
that
cell
embryo
many
mitosis
nuclear
division
genetic
stability
is
the
that
type
of
maintains
division
is
cytoplasm
the
the
position
mitosis
and
in
the
cell
discuss
the
role
of
mitosis
also
known
divides
as
into
a
zygote.
two
cells.
Almost
This
asexual
that
repair
This
in
a
size
cell
give
that
produced
hollow
as
the
divides
two
new
occurs
are
maintains
development,
When
a
surface
cell
ball
zygote
its
cells
identical
of
cells
but
nucleus
cells,
as
genetic
the
reaches
membrane
carbon
and
each
is
now
with
each
formed.
growth
a
in
first
and
nucleus.
number
other
This
composed
divides
increase
to
is
and
to
of
then
the
Mitosis
like
the
this.
is
The
parent
stability
cells
a
in
the
certain
embryo
size
it
is
gain
nutrients
unable
to
and
support
grow
itself
as
in
the
dioxide
is
fast
not
large
enough.
enough
This
is
to
absorb
because
as
enough
cells
oxygen
become
or
larger
surface
area
does
not
increase
enough
to
support
the
increase
in
the
cloning.
volume
the
of
protoplasm
surface
cells
divide
unicellular
yeast.
1
to
division
are
same
time
a
reproduction,
the
replacement,
the
Each
until
in
lose
growth,
cell,
zygote
cycle
cell

a
cell
size.
division
egg
of
Later
replication,
fertilised
fertilisation
divides
nuclear
nucleus.
describe
a
continues
about
cells.
nuclei

after
to:
by

as
you
immediately
should
selection
Cell division
Y
ou
completion
natural
(1)
Learning outcomes
On
and
area
to
into
two
volume
after
eukaryotic
Their
(cytoplasm
nuclei
ratio
plus
becomes
growing
organisms,
divide
by
nucleus).
for
a
such
mitosis
smaller
.
while
as
and
As
and
This
you
Amoeba,
then
cells
the
increase
is
one
can
reason
see
this
Paramecium
cell
divides
in
size
why
in
and
by
binary
nuclear division
fission
Figure
2
cycle.
this
or
by
2.1.2
This
budding.
shows
shows
These
the
are
events
that
after
a
forms
that
cell
of
occur
is
asexual
in
a
formed,
reproduction.
stem
the
cell
during
following
one
events
cell
occur
in
sequence:

growth

DNA
of
cytoplasm
replication

mitosis

cytokinesis
(cytoplasmic
3
division).

growth
DNA
of
cytoplasm
replication
occurs
in
the
‘S’
phase
of
interphase.
‘S’
stands
for
4
synthesis.
The
molecules
are
molecules
G
‘G ’
phases
made
such
to
as
are
growth
synthesise
nucleoside
phases
new
during
membranes
triphosphates
are
which
and
biological
new
made
in
organelles.
In
preparation
1
cytokinesis
for
replication
attached
to
and
tRNA
transcription.
molecules
Amino
ready
for
acids
are
synthesised
and
translation.
5
Replication
almost
information
parent
Figure 2.1.1
cell.
always
inherited
If
by
replication
gives
the
is
rise
two
not
to
identical
daughter
like
this
DNA
cells
then
is
the
so
the
identical
cells
may
genetic
to
that
of
the
differ
This Amoeba is dividing into
genetically
and
not
function
together
in
a
tissue.
The
immune
system
two by binary fission. The nucleus divides
detects
before the cell divides into two.
cells
expressing
Occasionally
reading
Link
Use
the
to nd lm
of
and
stem
rate
of
for further
page
144.
during
polymerase.
cells,
can
that
lose
Some
have
the
lost
ability
and
eliminates
replication
of
these
the
to
in
spite
inuence
power
respond
to
of
the
proof
mitosis.
divide,
to
them.
can
signals
start
that
to
divide
control
their
division.
asexually
by
information
budding
refer
multicellular
organisms,
mitosis
is
involved
in:
and

growth

repair

replacement

asexual
of
cells
and
tissues
to
other
76
cells
occur
proteins
dividing. Yeast
In
reproduces
mistakes
DNA
Differentiated
internet
Paramecium
by
different
following
damage
wounding
or
144–7).
reproduction
(see
pages
Module
In
multicellular
to
form
out
specific
continue
and
skin
functions.
there
white
divide
time.
cells
If
These
dividing
example,
red
organisms
tissues.
cells.
damaged
cover
the
animals,
to
cells
the
produced
differentiate
mitosis
replace
is
In
stem
blood
to
skin
that
by
are
cells
cells
Stem
cells
by
wound
a
the
in
the
cut
division
and
the
base
the
same
replace
for
of
that
the
the
are
For
cells
damaged
off
are
classied
in
all
divide
of
the
the
to
form
cells
they
cells
can
stem
plants,
are
areas
and
the
Cell
The
meristematic
where
these
cambium
cells
cells
that
are
are
gives
the
equivalent
found:
rise
to
examples
xylem
and
of
stem
are
root
phloem
changes
cells)
cells.
that
occur
mitotic
to
a
cell
cell
between
cycle .
During
one
the
division
cell
to
form
two
daughter
nuclei
followed,
in
the
(such
cytoplasm
to
give
two
daughter
cells
each
tips,
and
the
cases,
with
cells
shoot
nuclear
division
is
not
followed
by
in
fungi
that
have
hyphae
(long
thin
types;
of
of
stem
adult
marrow
one
or
two
the
next
nucleus
by
the
its
own
foc us
are
not
call
interphase
cytoplasmic
threads)
that
a
‘resting
divides
cell
is far from
being
‘at
rest’
division
interphase:
DNA
is
replicated,
nucleus.
division
are
are
synthesised,
as
membranes
happens
cell
bone
cell
tips
macromolecules
Sometimes
range
Embryonic
all
as
the
stem
types.
during
of
produce
of
tissues.
cycle
most
to
can form.
produce
stage’. A
first
according
S tudy
the
types
Meristems
Do
as
selection
tissues.
cycle
known
natural
different
cells
tissue
In
and
Did you know?
There
to
epidermis
variation
carry
replacement
rubbed
stem
the
cells.
the
Genetics,
together
to
ability
more
marrow
remain
specialised
retain
more
surface
then
then
cell
become
cells
bone
cells
at
and
stem
produce
in
by
to
2
and
organelles
are
not
made.
subdivided
into
cells.
cytokinesis
p
h
a
s
na
pa
ah
es
m
e
t
a
p
h
a
s
e
o
esa
hpo
let
mitosis
Link
Prokaryotes
e
cell
since
G
G
do
not
divide
by
mitosis
differentiates
they
linear
phase
do
not
have
chromosomes.
nuclei
See
and
page
144
1
phase
2
for
stem
S
phase
replication
cell
a
description
binary ssion
in
of
replication
and
bacteria.
continues
of
to
divide
DNA
Figure 2.1.2
The mitotic cell
cycle. Mitosis takes about
5–10 per cent of the cycle.
Summary questions
The
rate
of
cell
division
is
controlled
by
proto - oncogenes
that
stimulate
1
cell
division
and
tumour
suppressor
genes
that
slow
cell
Explain
the
nuclear
A
mutated
proto - oncogene,
uncontrollably.
If
a
tumour
called
an
oncogene,
suppressor
gene
stimulates
mutates
it
cells
becomes
to
the
rate
of
cell
division
to
increase.
Cells
that
start
to
and
divide
Suggest
are
often
removed
by
the
immune
system;
if
not
they
into
tumours,
such
as
benign
and
malignant
to
a
explain
cell
what
that
does
would
not
may
receive
grow
and
divide
happen
uncontrollably
between
cell division
inactive,
2
allowing
difference
division.
a
nucleus
during
cell
cancers.
division.
Mitosis
ensures
that
each
new
cell
has
exactly
the
same
genetic
3
information
as
its
parent
cell.
All
the
cells
in
the
body
(with
the
Explain
why
important
of
gametes)
have
identical
genetic
information
so
that
they
can
all
a

two

the
result
of
replacement.
Explain
in

number
other
genetic
nuclei
of
and
are
produced
chromosomes
the
stability
is
same
as
in
the
maintained
the
in
the
daughter
cells
as
daughter
parent
because
in
the
a
nuclei
are
the
same
the
genetic
is
no
genetic
a
asexual
reproduction
differs from
unicellular
organism,
as
such
as
eukaryotic
Amoeba
or
Paramecium
nucleus
parent
in
information
is
the
Outline
the
events
that
occur
cell
during
there
how
prokaryote
that
5
same

is
repair
mitosis:
daughter
each
stability
growth,
efficiently.
4
As
during
work
and
together
genetic
exception
the
mitotic
cell
cycle.
variation.
77
2.2
Mitosis
(2)
DNA
Learning outcomes
Y
ou
On
completion
should
be
able
of
this
section,
you
can
garlic.
to:
name
the four

describe
stages
of
processes
The
a
that

make
stages
the
of
cells
growing
meristem.
tip
cell
Score
the
garlic
of
to
show
2
After
mitosis
from
of
the
yourself
root
shoots
this
tip
and
of
roots
Here
is
a
procedure
underside
of
a
clove
to
if
a
is
followed
you
make
plant,
where
follow
such
a
mitosis.
temporary
as
mitosis
with
by
onion
is
or
localised
cloves
of
is
garlic.
of
garlic
with
a
sharp
knife
and
suspend
3
Cut
a
over
day
water
remove
so
the
some
base
just
intact
touches
the
water
surface.
off
10–20 mm
on
a
watch
of
the
glass
root
(or
Heat
Put
in
(The
of
acid
shallow
a
small
dish)
for
volume
10
of
ethanoic
minutes.
–3
10–25 cm
bath.
1 mol dm
hydrolyses
hydrochloric
the
DNA
acid
forming
to
60 °C
in
deoxyribose
a
water
aldehydes
foc us
which
carefully
at
Figure
2.2.
1
and
identify
the
react
holds
plant
W
ash
the
with
cells
the
stain,
and
hydrolyses
the
middle
lamella
that
together
.)
and
5
2.2.2
tips.
other
3
S tudy
roots.
the four
4
Figure
for
and
mitosis.
acid
Look
cycle
mitosis
diagrams
stages
the
of
the
occur
the
during
see
during
mitosis
1
the
replicated
preparation
called

is
root
tips
in
cold
water
for
4–5
minutes
and
dry
the
hot
on
filter
stages
paper
.
of
mitosis
in
the
photomicrograph.
6
Then
try
Summary
question
Use
a
mounted
needle
to
transfer
the
root
tips
to
3.
hydrochloric
7
W
ash
filter
8
Use
the
root
the
Use
a
Add
a
blue
Break
12
Place
of
leave
again
for
in
5
cold
minutes.
water
for
4–5
minutes
and
dry
on
a
remove
the
of
to
remove
slip
for
2
with
over
gently
slip
all
keep
but
the
two
root
tips
onto
a
clean
2 mm
gently
the
growing
root
tip.
(acetic- orcein)
stain
or
toluidine
minutes.
a
the
to
from
tips.
ethano - orcein
leave
tissue
press
cover
but
drop
and
cover
and
the
to
rest,
small
up
needle
slide.
the
stain
11
slip
tips
mounted
scalpel
Discard
10
and
paper
.
microscope
9
acid
mounted
root
spread
with
needle.
tips.
the
the
Place
cells.
blunt
filter
paper
over
Alternatively,
end
of
a
the
tap
mounted
the
cover
surface
needle
or
pencil.
13
Use
the
those
low
in
power
Figure
Y
ou
of
may
prepared
slides.
be
the
show
what
plant
to
search
form
also
that
way
–
a
the
the
the
during
cells
they
furrow
drawings
above
diagrams
happens
and
the
make
described
from
Plant
spindle
not
Figure 2.2.1
cell.
to
way
that
made
chromosomes
the
microscope
asked
in
Note
drawings
to
the
slide
for
cells
like
2.2.1.
to
the
not
have
across
have
cell
the
chromosomes
an
cell
are
so
the
during
in
have
not
diagrams
centrioles
animal
drawn
are
are
cell,
centrioles
walls
you
prepared
2.2.2
They
nucleus,
in
slides
from
Figure
microscope.
mitosis
do
in
from
or
for
and
not
a
organising
membrane
cytokinesis.
a
does
Note
diagrammatic
Photomicrograph of plant cells dividing by
they
do
not
look
like
this
in
real
cells
as
you
can
tell
mitosis
by
In
plant
cellulose
of
the
with
78
cells
of
cell
an
a
cell
and
plate
animal
looking
plate
other
to
cell.
forms
cell
divide
carefully
wall
the
at
the
across
the
materials.
cell
into
photograph.
middle
of
the
Membrane
two.
There
is
cell.
forms
no
This
on
furrow
is
made
either
as
side
there
is
Module
2
Prophase
centriole
DNA
is
wound
chromatin
chromatids
Centrioles
envelope
the
up
so
it
condenses.
attached
move
to
breaks
is
packaged
Each
to
each
opposite
up
into
into
other
poles
small
at
of
pieces
S tudy
chromosomes. The
chromosome
a
has
Microtubules
centromere.
the
cell. The
that
foc us
two sister
protein
nuclear
disperse
through
cytoplasm.
make
of
hollow
the
and
are
made
molecules
globular
together
tubes. They form
cytoskeleton
can
of
joined
quickly
be
(cell
to
part
skeleton)
assembled
and
Metaphase
broken
Chromosomes
cell,
which
is
metaphase
by
to
called
pole,
others
so
across
the
organise
that
attach
to
the
DNA forming
the
the
middle
equatorial
microtubules. Some
chromosomes. The
replicated
themselves
plate. Centrioles
assembling
pole
arrange
sometimes
the
spindle
centromeres
chromatids
in
mitosis.
the
of
apparatus
extend from
the
centromeres
can
as
plate or
microtubules
the
of
down
separate
in
is
the
next
stage.
S tudy
foc us
Anaphase
Spindle
microtubules
are
anchored
at
the
centrioles
so
when
Look
they
are
broken
down
they
shorten
pulling
the
at
videos
chromatids
opposite
apart. The
poles
chromatids
with
have
chromosomes,
sister
the
separated
each
chromatids
centromere
they
composed
are
of
pulled
leading. Once
become
one
animations
and
time
lapse
sister
of
mitosis
online.
to
the
sister
single-stranded
molecule
of
DNA.
Telophase
Chromosomes
arrive
reappears. The
nuclear
endoplasmic
at
the
poles
envelope
and
uncoil. Chromatin
reforms from
pieces
of
rough
reticulum.
S tudy
foc us
Cytokinesis
During
cells
a
which
The
or
after
ring
of
telophase
the
cytoplasm
microtubules forms
contracts
to
draw
membrane fuses
so
in
the
below
divides.
the
membrane
separating
the
In
cell
to form
two
new
animal
membrane
a furrow.
You
must
stages
them.
of
be
to
identify
and
Remember
the
sequence
interphase
and
cells.
cytokinesis
Figure 2.2.2
able
mitosis
are
not
stages
of
mitosis.
The stages of mitosis in an animal cell.
Summary questions
1
Explain
plant
why
the
cells
in
the
diagrams
on
this
page
are
animal
cells
and
not
cells.
2
Explain
3
Identify
how
the
mitosis
stage
of
maintains
the
genetic
mitotic
cell
stability.
cycle
shown
by
each
cell
in
Figure
2.2.
1.
4
Make
walls
5
a
drawing
as
Arrange
cycle.
two
your
(You
of
lines
one
with
drawings
may
need
cell from
a
gap
so
to
they
cut
each
between
up
show
your
stage.
(Remember
to
show
the
cell
them.)
the
stages
drawings
as
they
occur
in
and
stick
them
into
the
cell
your
S tudy
notebook
in
the
correct
When
6
List
what
happens
to
a
chromosome
during
a
complete
mitotic
cell
Describe
what
happens
to
nuclei,
nuclear
envelopes,
centrioles
and
answering
Summary
question
cycle.
6,
7
foc us
sequence.)
the
do
not forget
the
three
stages
of
cell
interphase.
membrane
to
make
during
sure
you
one
complete
describe
what
cell
cycle. You
happens
to
could
each
tabulate
structure
in
your
each
answer
of
the
stages.
79
2.3
Life
cycles
Learning outcomes
Meiosis
The
On
completion
of
this
section,
other
type
chromosomes
should
be
able
state
that
nuclear
meiosis
division
is
the
that
type
halves
of
nuclear
a
division
nucleus
is
is
meiosis,
halved.
This
is
in
which
essential
the
in
number
of
organisms
every
number
time
two
so
that
gametes
the
fuse
number
of
chromosomes
does
not
that
double
together
.
human
life
cycle
starts
at
conception
when
a
sperm
fertilises
an
ovum
and
(egg
variation,
sexually
the
The
chromosome
promotes
in
to:
reproduce

of
you
not
cell).
The
fertilised
egg
or
zygote
has
two
sets
of
chromosomes
–
a
genetic
paternal
set
inherited
from
the
father
and
a
maternal
set
inherited
from
the
stability
mother
.

describe
the
human
life
produced
cycle
retain

explain
the owering
plant
This
cell
from
the
is
this
ability
diploid
diploid
to
as
it
cell
divide.
has
by
They
two
sets
mitosis
of
are
differentiate
chromosomes.
also
to
diploid.
become
But
All
the
not
cells
all
specialised
and
life
often
lose
the
ability
to
divide.
Some
cells
remain
undifferentiated
during
cycle
development

describe
the
role
of
meiosis
in
and
enter
the
developing
sex
organs
as
the
gamete-forming
life
tissue.
These
cells
are
the
germ
line
cells.
Cells
like
this
in
the
ovary
cycles.
divide
Did you know?
by
just
before
two
start
are
around
specialised
cells
200
in
different
the
human
and
is
a
plants
by
In
very few,
producing
but
biological
a
they
greater
are
will
see
have
the
of
one,
role
sets
that
two,
of
refers
of
cells
to
is
involved
organisms
three, four
is
to
or
number.
Mitosis
ploidy
number,
whatever
to
of
can
do
not
The
cells
gametes).
process
in
the
that
making
until
month
form
Sperm
after
to
cells
They
of
stop
puberty
form
that
ova
sperm
at
when
a
time
one
or
(female
divide
production
millions
production
these
generates
have
two
Each
chromosome.
22
plus
an
or
a
correspond
abbreviations
cells
of
have
gametes
one
set
of
variation
in
the
by
starts
every
meiosis
at
to
puberty
day.
to
halve
the
number
chromosomes.
nuclei
X
Y
set
of
of
chromosomes;
chromosomes
Humans
have
chromosome
chromosome.
with
n
sets
that
the
and
size
2n
are
of
23
and
the
used
contains
are
They
of
are
produced.
males
numbers
organism
to
signify
of
as
nuclei
one
chromosomes
human
The
haploid
Species
the
maintains
in
have
example
a
set
having
one
of
with
22
each
plus
an
in
you
the
haploid
can
and
see
in
set
females
chromosomes
a
X
set
table.
diploid.
Haploid
number
the
Diploid
(n)
number
that
Drosophila melanogaster
4
8
23
46
12
24
10
20
20
40
28
56
39
78
be.
human,
Homo sapiens
Pride
Barbados,
Field
of
mustard
Caesalpinia pulcherrima
(‘fast
elephant,
Loxodonta africana
dog,
mouse,
Brassica rapa
house
in
common
multiple
with
sets
Mus musculus
Canis familiaris
adder’s tongue fern,
*
plant’)
European
domestic
80
line
each
meiosis.
chromosomes
nuclei
fruit y,
happens
germ
(male
state
by
more;
halve
ploidy
so
Meiosis
chromosome
the
chromosomes. You
and
meiosis
testis,
cells
chromosomes.
type
having
number
this
approximately
continuous
Sets of
foc us
–ploid
in
divide
of
of
sufx
remain
to
capable
variety
Diploid
The
start
comparison
molecules.
S tudy
then
body.
haploid.
of
and
the
chromosomes
have
and
divide
sperm
Meiosis
Flowering
birth
to
gametes).
produce
There
mitosis
of
Ophioglossum reticulatum
many
ferns,
this
chromosomes,
species
not
just
is
likely
two
sets.
630
to
be
polyploid,
1260*
so
there
are
(2n)
Module
The
process
The
fact
that
it
gains
of
that
is
not.
one
type.
the
Meiosis
At
egg
set
nucleus
nucleus.
maternal
The
is
pollen
rise
within
Pollen
to
the
set
of
and
the
apart,
fusion
and
plant
life
since
cells
the
is
the
divide
and,
is
random
tell
ensures
since
it
came
maternal
males
the
X
cell
that
from
in
the
of
came
and
and
natural
selection
Did you know?
Not
chromosome
chromosomes
it
process.
variation
implies
daughter
of
Genetics,
XX
each
all
the
is
animals
same
male
have
way
as
and XY
sex
determined
humans;
in
birds
is female, for
example.
from
the
paternal
chromosome
is
origin.
of
are
a
type
origin
different
meiosis
spore
gamete
In
in
millions
Flowers
by
female
female
quite
1600
ancestor
.
not.
a
each
nuclei
since
to
not
that
two
in
paternal
paternal
is
are
possible
often
is
cycle
it
that
grain;
Y
is
is
is
chromosomes
each
gamete
there
of
so
with
maternal
set
it
most
the
of
that
is
set
controlled
chromosomes
other
but
and
number
complete
carefully
restored
common
contain
the
gives
a
is
one
Occasionally
surprising
shared
They
chromosome
chromosomes
origin
owering
hardly
we
in
is
of
chromosomes
the
gains
fertilisation,
number
One
sperm
cell
complete
represented.
diploid
halving
each
2
to
that
years
made
to
for
form
of
(1.6
sexual
spores.
multinucleate
unlike
the
humans.
billion
pollen
This
years)
is
since
reproduction.
The
male
structure
grain,
is
spore
that
retained
ower
.
grains
are
transferred
from
ower
to
ower
or
,
sometimes
within
Link
the
a
same
tube
ower
.
towards
If
the
pollen
transfer
female
spore.
is
successful
Inside
the
then
pollen
a
pollen
tube
is
a
grain
grows
nucleus
that
This
divides
female
other
by
mitosis
gamete
nuclei
nucleus
to
then
temporary
to
to
form
give
a
divides
store
form
of
a
two
diploid
triploid
by
male
in
zygote
and
endosper m
mitosis
energy
gamete
a
to
give
a
nuclei.
the
One
other
nucleus.
triploid
fuses
fuses
This
tissue
with
with
triploid
that
acts
is
an
outline
of
the owering
the
plant
life
cycle,
more
detail
which
is
described
in
two
on
pages
148
to
153.
(3 n)
as
a
seed.
Summary questions
adult flowering
plant
1
Dene
and
2
the
terms
haploid,
diploid
triploid
State
the
number
of
flower
chromosomes
mitosis,
growth
in
the
endosperm
and
tissue
development
of
Pride
of
Barbados,
Caesalpinia pulcherrima
stamens
carpels
3
Name
ten
specialised
cells
in
humans.
pollen
sacs
ovules
4
Explain
in
life
why
meiosis
is
necessary
cycles.
meiosis
seedling
5
Make
cycle
pollen
grains
embryo
a
meiosis
seed
and
the
life
where
and
gamete
Some organisms
cycles with
as
fertilisation
embryo
zygote
mitosis
occur
on
diagram.
germination
6
female
show
Indicate
dispersal
your
gamete
to
humans.
sac
mitosis
male
diagram
of
have
life
short diploid
meiosis occurs
soon
stages
after
in
fertilisation. These organisms
embryo
are
seed
haploid for
mitosis,
growth
cycle.
such organism
is
Plasmodium
inside fruit
that
Figure 2.3.1
life
and
One
development
most of their
causes
malaria.
Find
a
life
The owering plant life cycle
cycle diagram for this organism
and
suggest the
advantages
disadvantages of
most of the
life
being
and
haploid for
cycle.
81
2.4
Meiosis
Meiosis
Learning outcomes
two.
On
completion
should

be
state
able
that
divisions,
of
this
section,
The
divisions
you
name
the
meiosis
meiosis
consists
I
and
of
during
obvious
with
difference
mitosis
is
that
so
the
it
is
easy
nucleus
to
goes
confuse
through
the
two
meiosis:

meiosis
I
meiosis
stages
of
meiosis
I
the
processes
that
–

meiosis
II
homologous
chromosomes
separate
–
chromatids
separate.
II
main
ways
in
which
meiosis
differs
from
mitosis
are
as
follows:
and

describe
most
in
similarities
two
II

many
to:
The

has
meiosis
has
meiosis
II
two
divisions
of
the
nucleus
known
as
meiosis
I
and
occur

mitosis
has

meiosis
only
one
division
meiosis.
I
involves
the
pairing
and
separation
of
homologous
chromosomes
S tudy
Take
care
mitosis.
and
lose
is
homologous
chromosomes

there
are
four

there
are
two

the
chromosome
number
is

the
chromosome
number
remains

daughter
nuclei
are

daughter
nuclei
produced
daughter
do
not
nuclei
at
associate
the
end
with
of
each
meiosis
other
in
mitosis
II
foc us
over
It

writing
easy
marks
to
as
a
meiosis
misspell
daughter
nuclei
at
the
end
of
mitosis
and
halved
in
meiosis
I
them
the
same
in
mitosis
result.
number
as
the
haploid
parent
in
in
meiosis
mitosis
have
the
same
chromosome
nucleus
Link

daughter
parent
If
you
are
unsure
about
in
mitosis
and
what
it
over
pages
daughter
you
what
once
nuclei
and
II.
look
produced
the
parent
through
the
thing
This
halves
does
The
in
from
each
other
and
from
the
in
mitosis
are
genetically
identical
to
each
nucleus
in
The
not
egg
162
in
this
the
but
egg
of
It
because
an
not
2.4.2
from
do
the
in
two
starts
of
egg,
daughter
meiosis
again
and
II
Figure
that
cells
the
The
in
meiosis
haploid
animals
in
2.4.2,
if
chromosome
mitosis.
halve
show
the
I
think
divides
number
divide
in
chromatids
an
that
the
meiosis
of
each
number
II.
animal
daughter
spore
follow
cell
chromosome
meiosis
in
a
cells.
cell.
In
this
Details
production
in
case
of
plants
are
respectively.
takes
for
might
the
in
in
four
differentiate
cells
meiosis
half
when
they
does
148
state
the
as
of
Y
ou
have
again
production
and
beginning
formation
nuclei
Figure
cells
arrested
above,
I.
humans
potential
until
in
diagrams
happen
separate
produced
haploid
process
in
in
pages
the
chromatids.
happen
meiosis
are
meiosis
the
daughter
diagrams
sperm
to
will
chromosome
before
each
over
the
into
40
years
divides
to
birth,
menstrual
division
cytoplasm
sperm
months
of
cells
but
is
cycle.
before
the
(see
produce
arrested
Some
they
nucleus
unequally
to
page
mature
eggs
is
the
may
large
whole
Meiosis
meiosis
remain
meiosis.
same
one
The
sperm.
during
complete
give
162).
as
I
in
In
the
shown
cell
(the
Stages of meiosis during
formation of pollen grains in a owering
82
to
happens
and
same
plant
different
76–79.
As
Figure 2.4.1
genetically
meiosis
is for,
other
look
are
in
what

happens
nuclei
nucleus
secondary
a
nucleus.
oocyte)
and
three
tiny
cells
that
each
consist
of
little
more
than
Module
Meiosis
early
prophase
Genetics,
variation
and
natural
selection
I
Prophase
I
2
I
centriole

chromosomes
in

the
light
homologous
chiasmata
prophase
I
details);

at
the
join,
metaphase
I
end
of
move
to
I
move

the
paternal
anaphase
all facing
microtubules
Telophase
the
of
hold
parts
after
thicker;
they
(or
the
together;
crossing
spindle
in
over
over
breaks
endoplasmic
other
diagram
chromosomes
in
are visible
is
maternal
unshaded
(see
non-sister
page
85 for
more
complete
up
into
small
reticulum;
sacs
of
centrioles
replicate
microtubules
metaphase)
(in
this
are
crossing
chromosomes
bivalents
in
chromosomes
envelope
the
and form
equatorial
same
to
nuclear
part
poles
other
attach
of
plate
each
words
bivalent
the
position
paternal
themselves
chromosomes
are
pole)
to
the
centromere
chromosomes
microtubules
poles
of
each
chromosome
if
this
was
(each
towards
anaphase
with
the
of
two
poles;
chromatids)
chromatids
are
pulled
would
be
by
the
pulled
to
mitosis
I
chromosomes

the

of
the

nuclear
number
I
and
I
opposite
telophase
the
I
maternal
double-stranded
shortening
I
shorter
bivalents;
paternal
exchange
become
to
and
independently

become
to form
the
become visible
opposite
bivalents
Anaphase
they
pair
and
and
prophase
Metaphase

that
chiasma) form
break
which

not
shaded
chiasmata
membrane,
and
are
(singular
chromatids
late
so
chromosomes
chromosomes

condense
microscope
of
reach
the
envelope
opposite
reforms
chromosomes
cytokinesis
occurs
cytoplasmic
–
the
bridges
of
to
the
cell
poles
make
surface
between
two
parent
the
daughter
cell
–
these
nuclei
nuclei
membrane forms
that
are
have
half
the
haploid
a furrow
leaving
small
cells
Interphase
An interphase may occ ur between the divisions of meiosis
I and II in which case the
chromosomes uncoil. Cytokinesis may also occur at this stage, but not in all organisms .
prophase
Meiosis
II
II
Prophase

II
centrioles
meiosis

nuclear
replicate
and
move
to
the
poles
that
are
at
right
angles
to
those
in
I
envelope
Metaphase
breaks
up
as
in
prophase
I
II
Summary questions
metaphase
II

individual
double-stranded
chromosomes
align
on
the
1
equator
with
their
Explain
that
randomly

why
the
microtubules
attach
to
i
the
halves
ii
does
during
not
meiosis
Anaphase
important
number:
meiosis
halve
I;
during
II.
II
II

sister
the
chromatids
centromere
break
and
apart
move
at
2
Describe
what
opposite
poles
by
shortening
anaphase
as
meiosis
nuclear
envelopes
haploid
genetically
Make
reform
nuclei
that
different
to
to
what
give
are
a
table
and from
cytokinesis
all
the
happens
compare
what
meiosis
with
I
to
in
meiosis
include
II.
similarities
one
parent
may follow,
but
well
as
differences.)
cell;
not
in
4
Identify
the
stage
of
meiosis
organisms
shown
Figure 2.4.2
to
during
(Remember
as
another
I
II.
II
II
four
a
in
happens

to
meiosis
I
3
Telophase
during
of
and
microtubules
happens
to
chromosome
telophase
is
chromosome
arranged
centromeres
anaphase
it
chromatids
The stages of meiosis in an animal cell to produce sperm cells
in
describe
the
Figure
what
is
2.4.
1
and
taking
place
to
chromosomes.
83
2.5
Segregation
Learning outcomes
completion
of
this
section,
individual
be
able
one
state
give

that
rise
processes
to
describe

explain
over
in
heritable
the
segregation
meiosis
chromosomes
organisms
another
.
With
produced
by
the
exception
sexual
the
same
of
reproduction
identical
twins
are
we
different
are
genetically
to:
unique.

over
you
from
should
crossing
Segregation of
All
On
and
process
of
meiosis
variation
of
random
chromosomes
in
types
All
of
genes
between
known
alleles
members
determine
individuals
as
are
of
alleles
are
that
expressed
the
environment.
the
environment
the
in
features
caused
we
have
the
Genes
species
by
the
of
each
provide
the
the
(see
same
species.
different
inherited
phenotype
have
depends
Genetic
versions
page
72).
on
inheritable
genes
of
genes,
way
these
interaction
variation.
the
differences
the
The
the
since
The
with
effect
of
I
the
process
during
of
prophase
on
the
expression
of
those
genes
is
not
inheritable.
crossing
I
During
of
meiosis
information
meiosis.
these
is
first
of
The
chromosomes
daughter
each
I;
Cell
changes
that
changes
nucleus
or
is
are
to
from
the
one
Pairing
of
segregation,
A
chromosomes
one
halving
arranged
receives
chromosome.
separation,
occur
passed
of
into
set
generation
of
the
homologous
to
pairs
occurs
in
the
the
genetic
next.
The
number
.
so
with
that
one
chromosomes
chromosomes
Cell
rearrange
cells
chromosome
chromosomes
homologous
of
to
of
each
example
occurs
in
anaphase
of
prophase
I.
B
diploid
(2n

first
cell
4)
meiotic
division
second
meiotic
division
haploid
Figure 2.5.1
haploid
cells
cells
Random segregation of homologous chromosomes in meiosis I. Maternal chromosomes are shaded darker; paternal
chromosomes are lightly shaded.
The
S tudy
arrangement
is
entirely
random.
homologous
Make
sure
you
know
the
Check
and
the
the
terms
gene
glossary for
always
paternal
try
to
use
pairs
In
of
Figure
and
maternal
2.5.1
you
chromosomes.
can
chromosomes
They
see
can
this
at
metaphase
happening
either
line
up
as
with
I
two
shown
in
difference
cell
between
of
foc us
and
the
A
or
as
in
cell
B.
There
is
a
50%
chance
chance
they
will
that
they
will
be
in
allele.
alignment
A
and
This
rise
a
50%
be
in
alignment
B.
meanings
them
correctly.
gives
different
to
inherited
mixtures
of
variation
maternal
and
because
paternal
each
nucleus
contains
chromosomes.
Link
Y
ou
II
Random
segregation
in
can
see
Figure
the
results
of
this
in
the
haploid
nuclei
at
the
end
of
meiosis
2.5.1.
of
23
chromosomes
results
of
the
is
responsible for
dihybrid
cross
as
the
shown
Random
segregation
combinations
of
during
maternal
meiosis
and
in
humans
paternal
can
generate
chromosomes
2
different
(8 388 608).
At
23
on
pages
84
98–99.
fertilisation
the
in
zygote.
a
human
number
of
possible
combinations
is
therefore
2
23
×
2
Module
2
Genetics,
variation
and
natural
selection
Crossing over
When
wind
homologous
around
chromatids
between
possible
to
touch
see
I
is
over
This
Crossing
over
chromatids.
nucleotide
this
is
were
to
nucleotides
are
many
Genes
in
the
are
a
of
close
crossing
over
and
crossing
over
does
over
the
that
to
so
and
of
prophase
point
sections
has
at
occurred
where
are
chromosomes
part
that
has
to
I
exchanged
it
is
the
The
that
they
two
separate
as
chiasmata.
would
or
,
on
so
maternal
alleles
are
occur
if
breakage
occurs
may
be
in
gained
that
the
not
early
in
at
lost
to
be
by
Did you know?
a
gene.
of
there
and
split
is
average
the
just
than
Loss
as
on
The
for
gene
harmful
not
part
single
all.
switched
tend
‘clusters’.
or
a
resulting
as
are
and
genes.
within
protein
just
chromosome
together
origin
occurs
no
genes
in
different
not
it
and
likely,
how
of
precise
point
more
genes
a
of
genes
be
crossover
divide
over
one
as
human
of
chiasmata
of
Nos
small
21
and
chiasmata
chromosomes
two. There
chromatids
such
number
large
is
rarely
between
more
the
chromosomes,
22.
off.
up
by
Occasionally
them.
A
A
pair
each
chromatids
are
control
inherited
occur
another
that
between
together
are
the
combinations
protein
DNA
At
breaks
as
non-sister
mutation
regions
beginning
over
at
inactive
the
exchange
one
precisely
added
happen
sections
that
very
crossing
or
an
to
different
fact,
produce
DNA
and
between
at
together
.
Later
chromosomes
occurs
pair
stay
the
crossing
gives
lost
other
attached
gives
In
they
breakage
DNA
called
paternal.
so
chromatids.
where
of
Crossing
would
each
remain
exchange
prophase
If
chromosomes
other
non-sister
chromatids
and
each
B
A
B
B
of
A
b
a
B
a
b
A
b
a
B
a
b
homologous
chromosomes
a
b
Summary questions
chiasma
1
Figure 2.5.2
Explain
what
is
meant
by
the
Crossing over between chromatids of a homologous pair and the effect on
term
heritable variation.
the alleles of two genes, A/a and B/b
Crossing
over
segregation
that
or
no
ever
adds
of
two
will
even
more
chromosomes.
humans,
have
the
with
same
variation
As
the
a
to
that
generated
result
of
all
this
exception
of
identical
by
variation
twins,
2
random
it
is
have
ever
Dene
is
thought
of
had
the
used
to
term
a
State
when
effects
that
of
an
generation.
random
segregation
individual
We
have
has
seen
and
inherited
four
ways
crossing
before
in
which
over
are
passing
to
‘shufe’
them
meiosis
on
to
generates
the
the
b
random

is
the
alleles
of
random
and
If
a
so
daughter
nuclei
contain
one
of
mixture
is
receive
show
of
random
paternal
cross
and
over
chromosomes
segregation
maternal
during
that
so
a
cells
a
I
halves
of
a
State
chiasmata
of
are
I
so
mixture
of
chromatids
of
maternal
is
also
and
random
paternal
–
often
DNA
b
describe
paternal
crossing
Make
one
the
the
chromosome
to
In
order
restore
gamete
the
the
and
body
for
the
are
end
number
,
meiosis
replication
diploid
not
are
by
not
to
I,
why
the
If
a
next
each
occur
number
.
identical.
inherited
that
of
is
there
a
need
Also
chromosome
these
chromatids
crossing
chromosome
generation
genetically
identical
has
for
over
with
there
and
will
occurs
two
will
will
two
the
other
be
not
that
occurs,
on
the
some
effect
the
process
of
over.
diagrams
of
crossing
alleles
B/b;
of
to
show
over
three
genes:
C/c.
Explain
the
in
cycle.
a
life
advantages
of
meiosis
to
the
groups
work
over
a
chromatids
two
crossing
chromatids
sister
have
so
I.
and
that
while
prophase
when
between
chromosomes
prophase
are
a
c
sister
mixture
At
chromatids
in
during
A/a;
division?
separate
in
why
formed
not.
chromatids.
sister
Explain
daughter
6
second
process
segregation.
a
segments
segregation
meiosis
segregate
chromosomes
nuclei
maternal
is
gene
5
contain
chromatid
one
one
chromosomes
homologous
the
the
and
variation
alleles
daughter

of
homologous
nuclei

chromosomes
meiosis,
inheritable:
pair

of
during
describe
next
4
that
it
promotes variation
occurs
genes
as
behaviour
chromosomes.
segregation
The
the
genotype.
3
Meiosis
segregation
describe
is
7
Explain
the
why
same
identical
twins
have
genotype.
of
together
.
85
2.6
Nuclear
division
This
summary
chapter
concerns
two
forms
of
nuclear
division,
mitosis
and
Learning outcomes
meiosis.
On
completion
should

use
be
able
and
mitosis

of
make
and
identify
this
section,
you
It
to:
the
is
a
good
mitosis
tables
to
each
events
stage
make
show
models
what
mitosis
of
to
the
and
in
about
explain
nuclear
and
differences
process
DNA
Mitosis
Meiosis
the


condenses
each feature
at
the
start


1
2
division
of
divisions
of
the
nucleus
in
importance
this
of
table
The
each
of
chromosome
the
daughter
number
same
nuclei
as
the
parent
(meiosis
I
and
meiosis
II)
half
number
the
parent
of
nucleus
the
nucleus




in
meiosis


in
both


in
meiosis
I


in
meiosis
II
only


in
meiosis
II
only

(promoted
division.
homologous
pair
to form
crossing
chromosomes
bivalents
over
occurs
chromosomes
at
the
are
metaphase
random
chromatids
opposite
genetic
arranged
move
of
variation
daughter
occurs
divide
poles
to
the
among

nuclei
(maybe
errors
in
a
little
if
replication)
crossing
of
and
1
the
meiosis
Make
II.
a
Y
ou
(see
divisions
cell
table
above
with
the
table
you
drew
to
by
over,
random
Compare
I
plate
segregation
centromeres
86
between
during
meiosis.
foc us
the
similarities
envelope
number
Think
the
table.
‘disappears’
of
S tudy
a
occur
chromosomes
happens
and
in
meiosis
nuclear

summarise
Feature
that
of
to
meiosis
compare
meiosis
during
during
idea
and
segregation
chromosomes)
compare
meiosis
I
II.
new
table
should
Question
be
3
that
able
on
compares
to
page
think
83).
of
mitosis
other
with
meiosis
features
to
add
I
and
to
meiosis
the
table
Module
The
table
that
occur
2
below
Match
and
one
each
letters
once,
is
during
list
event
to
more
a
of
meiosis
with
identify
than
stages
(1
to
a
or
meiosis
(A
to
H)
and
a
list
of
Genetics,
variation
natural
selection
events
or
events
not
at
stages
and
all.
of
meiosis.
stages;
Some
you
events
Use
may
the
use
occur
in
numbers
each
more
letter
than
stage.
S tudy
Event during
pairing
and
10).
stage
the
once
of
2
of
meiosis
chromosomes
Number
Stage of
meiosis
1
prophase
2
metaphase
3
anaphase
4
telophase
5
prophase
6
metaphase
7
anaphase
8
telophase
Devise
A
I
for
condensing
nuclear
of
chromosomes
envelope
bivalents
crossing
align
on
reforms
equator
of
cell
over
centromeres
separation
of
divide
homologous
foc us
Letter
your
own
matching
question
mitosis.
B
I
C
I
D
I
E
II
F
II
G
II
chromosomes
separation
of
sister
chromosomes
align
equator
cell
four
3
of
the
nuclei
The
on
the
10
content
shows
the
H
II
9
are formed
DNA
graph
chromatids
of
cells
changes
changes
that
throughout
the
cell
cycle.
This
occur
.
5
fo
yrartibra
/AND
stinu
7
6
4
ssam
3
2
1
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
time/hours
Figure 2.6.1
Explain
Changes in DNA content in a cell during a mitotic cell cycle
what
changes
in
happens
the
at
quantity
each
of
stage
DNA
of
the
shown
in
cell
cycle
Figure
to
bring
S tudy
about
Print
4
Make
models
of
chromosomes
using
pipe
cleaners
or
other
out
such
as
knitting
wool,
string
or
modelling
clay.
Use
them
of
the
different
stages
of
mitosis
and
that
the
advantages
chromosomes
during
of
making
nuclear
models
division.
to
What
of
the
notes
occur
in
each
on
stage
the
of
meiosis.
mitosis
Explain
photos
mitosis. Write
to
events
model
separate
suitable
stages
material
foc us
2.6.1.
show
are
the
the
behaviour
limitations
of
of
these
revise
on
separate
match
the
cards. When
photos
with
you
the
notes.
models?
87
2.7
Practice
Mitosis
This
section
can find
1
The
contains SAQs
MCQs
on
diagram
the CD
shows
a
on
at
and
mitosis
the
back
mitotic
cell
exam-style
and
of
meiosis
meiosis. You
this
questions:
The
book.
next
photograph
lymphocyte
in
is
another
an
electron
stage
of
micrograph
of
a
mitosis.
cycle.
cytokinesis
mitosis
G
1
(first
growth
phase)
G
2
(second
growth
phase)
S
(synthesis
phase)
b
a
Outline
the
processes
that
must
happen
Describe
during
interphase
before
a
cell
divides
by
what
is
happening
in
the
lymphocyte
during
the
stage
shown
in
the
electron
mitosis.
micrograph.
b
Name
the
stage
of
mitosis
in
which
each
of
the
c
following
Explain
the
advantages
occurs:
of
using
a
light
S tudy
i
chromosomes
chromosomes
move
to
c
the
v
at
centromeres;
condense;
opposite
reforms;
of
split
poles;
iii
iv
chromosomes
sister
ii
microscope
chromatids
nuclear
the
envelope
assemble
at
the
equator
than
role
of
mitosis
in
the
growth
the
Look
rather
lm
electron
at
of
some
time
mitosis
lapse
before
answering Question
2c.
of
3
and
A
student
made
a
series
of
sections
through
the
plants.
root
d
of
microscope.
the
animals
behaviour
foc us
study
chromosomes
cell.
Explain
to
State THREE
other
roles
of
mitosis
in
animals
tip
meristem
of
an
onion. The
student
counted
and
the
number
of
cells
in
each
stage
of
the
cell
cycle
plants.
and
e
Suggest
what
might
happen
to
the
daughter
presented
the
end
of
one
mitotic
cell
The
two
photographs
show
in
a
that
stages
of
the
it
cell
takes
13
hours
Number
Percentage
Length of
of
of
time of
cycle
anaphase
telophase
BETWEEN
the
photographs.
88
two
to
stages
the
of
to
cell
metaphase
happens
25 °C
Stage of
prophase
what
at
mitosis.
interphase
Describe
student
cycle.
cells
cells
each
a
table. The
cycle.
complete
2
results
cells
discovered
at
the
in
stage
stage/min
254
45
16
7
23
chromosomes
mitosis
shown
in
the
total
345
100
each
780
Module
a
Copy
the
of
and
the
total
length
b
c
complete
number
of
Suggest
of
the
about
stage
in
and
the
in
number
time
make
the
Describe
cells
of
table
each
counted;
each
what
ii
calculating
as
a
6
percentage
calculating
The
the
length
student
of
time
the
diagram
organisms
of
could
of
Genetics,
shows
reinhardtii, a
different
that
relative
cell
i
stage.
conclusions
the
by:
stage
2
this
variation
the
life
single-celled
divide
to form
mating
species
strains:
is
cycle
natural
of
gametes
and
selection
Chlamydomonas
organism. The
+
that
–. The
adult
are
of
haploid
number
17
.
each
diploid
zygote
cycle.
happens
immediately
and
after
to
a
root
tip
cell
during
fertilisation
telophase.
+
adult
gamete
cell
4
a
At
the
end
of
interphase
of
the
mitotic
cell
cycle,
division
human
cells
have
6
picograms
of
DNA
in
each
–
nucleus. The
diploid
number for
humans
is
a
Copy
and
complete
the
table
to
show
how
and
human
how
nuclei
many
at
chromosomes
different
stages
of
there
Copy
are
the
mitosis
b
and
meiosis.
c
Mass of
nuclear
per
division
pg
DNA
State
diagram
mitosis
number
the
Explain
and
indicate
where
occur.
of
chromosomes
in
the
zygote
gametes.
all
the
gametes
organism
why
are
genetically
d
nucleus
Describe
how
organism
prophase
cycle
produced from
identical
to
one
each
other.
chromosomes
per
and
the
in
adult
Number of
nucleus/
life
in
and
Stage of
adult
much
meiosis
DNA
gamete
46.
the
life
cycle
differs from
that
of
of
this
single-celled
humans.
of
7
The
human
diploid
number
is
46.
Human
mitosis
chromosome
end
of
Y
telophase
of
a
mitosis
No.
chromosome,
Make
a
anaphase
I
I
is
No.
diagram
segregation
prophase
1
of
of
the
22
to
largest
is
the
show
and,
the
smallest.
how
chromosomes
meiosis
apart from
leads
random
No.
1
and
No.
22
at
to variation.
of
b
i
Make
a
diagram
to
show
crossing
over
meiosis
between
prophase
II
chromosome
of
ii
meiosis
c
end
non-sister
Explain
Describe
how
what
No.
chromatids
of
1.
crossing
happens
over
to
increases variation.
chromosomes
No.
1
of
and
telophase
No.
22
during
anaphase
I
and
anaphase
II
of
of
II
meiosis.
meiosis
8
b
Explain
during
c
how
the
Explain
growth
how
variation
mitosis
of
meiosis
within
a
maintains
an
genetic
a
stability
give
rise
to
b
a
Explain
what
is
meant
by
the
animals.
terms
Use
your
term
c
5
diagram
metaphase
and fertilisation
of
a
chromosomes
animal.
population
Make
haploid
i
I
of ONE
as
in
they
how
of
homologous
appear
at
meiosis.
diagram
homologous
State
pair
would
the
to
explain
when
what
is
applied to
chromosomes
meant
by
the
chromosomes.
you
have
drawn
and
behave
differently
Explain
why
during
mitosis;
diploid
ii
The
Indian
muntjac
deer,
Muntiacus muntjak,
has
meiosis
lowest
diploid
muntjac
b
deer
Draw
number
have
diagrams
chromosomes
arrangement
a
to
in
at
of
any
diploid
mammal.
number
compare
the
metaphase
anaphase
I
of
of
of
the
behaviour
of
chromosomes
the
is
different
to
that
in
mitosis.
Female
six.
arrangement
mitosis
meiosis
with
in
of
the
this
species.
c
Describe THREE
ways
chromosomes
during
chromosomes
in
in
which
meiosis
the
behaviour
differs from
of
that
of
mitosis.
89
in
2
Genetics, variation
3.
1
Introduction
Learning outcomes
completion
should

be
dene
able
the
genetics,
of
this
section,
all
that
to
terms
inheritance,
features
our
‘skip
Inheritance
we
inherit
children.
features
People
from
our
sometimes
parents
say
that
and
pass
certain
on
such
human
a
is
generation’
the
from
passing
grandparents
of
features
from
human
features
that
to
one
their
grandchildren.
generation
to
another
.
genotype,
is
a
list
of
some
are
inherited
to
a
greater
or
allele
the
relationship
genotype
and
extent.
between

the
know
features
lesser
explain
inheritance
you
Here

selection
to:
phenotype,
gene and
natural
genetics
Human
We
On
to
and
phenotype
hair
colour
,
length
and
style

brachydactyly
(short
ngers
and
of
toes)
an

skin

free
and
eye
colour
organism.
S tudy
or
attached

intelligence

blood
groups,
ear
e.g.

polydactyly

freckles
(six

hitchhiker ’s

ability
ngers
ABO,
on
the
thumb
MN
Rhesus
to
taste
phenylthiocarbamide
out
features
and
how
the
listed
phenotypic
here
are


controlled
the
the
features
only
are
These
was
in
his
choice
and features
because
plants
he
had
tend
to
to
is
alleles
the
of
observed
that
cross-pollinated
he
chose
by
are
hand
mid-19th
sativum
At
time
the
and
inherited
it
are
gene
human
features
of
an
with
and
organism
other
biochemistry,
than
its
genes.
physiology,
anatomy.
of
an
will
Mendel
organism;
see
in
the
(1822–84)
it
usually
following
carried
refers
to
pages.
of
the
inheritance
of
different
features
in
out
the
a
garden
pea,
no - one
understood
involved
some
sort
how
of
features
blending
were
from
inherited
both
and
parents.
many
Mendel
the
rst
to
state
that
features
are
controlled
by
discrete
entities
that
passed
on
from
inheritance
parent
a
to
repeat
chromosome
experiments
to
offspring.
using
that
specially
complete
can
vary
We
He
now
deduced
for
the
to
give
dene
a
the
production
different
gene
particulate
of
a
as
a
length
nature
polypeptide.
forms
of
the
of
DNA
The
published
35
days. The
harvested
and
seeds
it
then
is
have
1866
not
in
a
are
known
polypeptide
scientic
appreciated
as
journal
until
his
alleles.
without
paper
a
was
the
beginning
of
the
20th
century.
In
1905,
William
and
coined
study
of
the
term
variation.
genetics
T
oday
the
to
mean
term
the
covers
all
study
the
of
aspects
germinated
possible
than
one
at
(1861–1926)
to
genes,
their
effects,
methods
of
control,
inheritance
and
DNA
get
technology,
much faster
in
was
forms
can
of
so
results
work
different
life
inheritance
immediately
his
His
These
bred
their
Bateson
that
genes.
codes
differently.
readership.
rediscovered
within
that
sequence
function
Mendel
Mendel’s
wide
plants’
involving
foc us
possible
relying
generation
such
as
genetic
engineering
and
gene
therapy.
on
per
Mendel
were
had
no
discovered
conrmed
90
one
many
Some
genotype;
environment.
you
Gregor
by
our
a
that
year.
as
controlled
(polygenic);
give
the
in
nucleotide
plants
genes
to
(either/or) fashion.
S tudy
results
two
phenotype.
can
on
cycle
or
do
human
inherited
pea
but
of
‘fast
features
constitution
century,
study
Pisum
are
discrete
one
our
appearance)
genetic
are
genes
and
to
the
have
was
was
features
the
of
we
Some
many
genes
all
part
that
effect.
by
anything
the
assumed
be
span
of
study. This
self-pollinate
to
are
Genotype
systematic
plant
both
(outward
the
lucky
no
morphology
In
Mendel
refers
are
genes
some
by
features
above
the
has
and
inuenced
Phenotype
Did you know?
listed
by
environment
(monogenic)
is
hand
inherited.
controlled
It
(PTC)
height
All
be
toes)
face
foc us
and
Find
and
lobes
as
idea
in
the
about
the
the
1870s
material
of
mechanism
and
it
was
of
not
inheritance.
inheritance.
until
1952
Chromosomes
that
DNA
was
Module
Animal
and
Barbadian
blackbelly
in
the
they
17th
chose
features
The
and
the
at
but
crossed
are
Jamaica
to
and
Hope
to
is
on
to
the
cattle
a
breeds,
European
hardiness
Farmers
produce
adapted
breed
descended
offspring
conditions
European
the
Hope
suitable
Farm
not
are
centuries.
Jamaica
T
wo
with
resistance
of
Hope
conditions.
milk
most
Genetics,
variation
to
of

heat

grow

disease

breed

give

have
Barbadian
natural
selection
80%
brought
sheep
continue
began
in
the
that
to
to
to
breed
breed
and
Barbados
from
animals
15%
and
with
The
of
genotype
and
the
5%
20th
tropical
high
Zebu
features
Zebu
of
to
give
African
the
conditions.
years
adapted
Holstein,
introduce
Jersey
,
early
was
conditions.
to
sheep
island.
Jersey
tropical
about
to
breed
tropical
breeds
from
selected
yields
cattle
of
were
disease
of
the
current
Holstein.
Figure 3.1.1
Features
and
breeding
sheep
18th
adapted
breeding
century
plant
2
blackbelly
Barbadian blackbelly sheep
sheep:
tolerant
coarse

heat

good
instead
parasite
throughout
lean
and
more
Features
hair
and
of
of
wool
the
year
(unlike
mild-avoured
stamina
Jamaica
(so
avoid
overheating
in
the
tropics)
resistant
and
Hope
are
other
meat
more
breeds
even
agile
on
of
poor
than
sheep)
food
most
breeds
of
sheep.
cattle:
tolerant
resistance
to
ticks
(insect
external
parasites)
and
tick-borne
diseases

high

survive
Many
of
carcass
and
milk
yield
on
the
are
presence
so
or
important
interested
to
in
plant
bananas,
to
degradation
farming
the
of
breeders
to
these
arid
of
such
wipe
that
We
the
in
a
improve,
and
cattle,
few
are
This
makes
milk
by
features,
controlled
generations.
as
yield
many
and
genes
improvement
Qualitative
are
breeds.
such
controlled
by
These
Commercial
such
single
features
farmers
as
genes
are
are
and
more
more
features.
as
crop
we
to
has
can
wheat
out
diseases;
land
to
involved.
named
conditions
practices.
understanding
are
only
of
try
features
environment.
horns
take
diseases,
tolerate
breeders
factors
quantitative
threaten
resistance
by
absence
may
that
quantitative
many
improvement
and
are
inuenced
as
pasture.
features
weight,
difcult
Some
poor
also
cope
of
need
secure
our
and
with
happened
only
genetics
rust
plants.
black
We
crops
as
a
grow
change
result
future
livestock
crops
that
climate
the
Sigatoka
need
of
of
in
food
and
attacks
have
saline
and
soils
the
irrigation
our
animals
that
that
and
poor
supply
crop
by
plants.
Summary questions
1
Explain
what
phenotype,
2
Explain
how
adapted
3
Explain:
apply
to
to
i
is
meant
genotype,
by
Barbadian
tropical
the
terms
genetics;
ii
the following
gene
and
terms:
inheritance,
genetics,
allele.
blackbelly
sheep
and Jamaica
Hope
cattle
are
conditions.
qualitative features
why
it
is
difcult
to
and
quantitative features
breed
cattle
to
improve
as
they
their
milk
yield.
91
3.2
Terminology
Learning outcomes
Genes
In
On
completion
of
this
in
section,
a
and
be
able
differentiated
state
that
a
DNA
that
codes for
production

state
that
gene
of
a
the
is
a
length
of
polypeptide
is
of
a
gene
on
make
the
are
cell
each
DNA
the
lengths
of
chromosome
molecule.
Genes
is
single-stranded
are
the
sections
of
and
so
this
there
but
of
code
are
control
DNA,
binds.
a
to
variety
uses.
lengths
of
promoter
genes
Some
of
between
is
that
are
may
areas
be
do
turned
sequences
there
it
In
DNA
transcription
as
between
of
polypeptides.
other
when
known
In
for
DNA
not
on
to
of
these
code
and
for
off.
which
There
RNA
non-coding
DNA
redundant.
a
diagrams
crosses
have
cells
genes
polymerase
It
genetic
results
by
polypeptides,
chromosome

one
used
str uctural
the
locus
are
that
position
of
to:
that

chromosomes
you
composed
should
genetics
to
and
explain
is
possible
position
shows
make
of
the
to
a
pinpoint
gene
loci
of
on
a
the
position
chromosome
some
of
the
genes
of
is
on
each
its
a
gene
locus
on
a
chromosome.
(plural
human
X
loci).
Figure
The
3.2.1
chromosome.
predictions.
a
glycoprotein
mitochondrial
protein
needed for
muscle
contraction
Humans
protein
which
have
46
includes
chromosomes
ribosomal
factor VIII
blood
clotting
factor
protein
During
meiosis
homologous
pigment
absorbing
chromosomes
separate,
so
that
each
nucleus
gene.
See
information
on
receives
page
one
84 for
pigment
absorbing
allele
more
cells
in
the
Figure 3.2.1
retina
were
is
hybrid is
varieties
different
used for
crosses
and for
the
the
crosses
in
a
gene
allele
between
of
a
All
their
same
between
for
tall
the
patterns
drawing
Each
the
of
band
are
you
stained
an X
can
to
banding
see
in
this
a
region
containing
purple
the
plants
of
many
page
99
–
of
as
light
the
retina
be
of
in
gene
were
in
the
of
has
gene.
In
the
this
next
ratio
allelic
one
his
I
+
of
tall
–
Each
results
the
the
retain
pea
you
and
gametes
law
he
page
at
the
with
owers;
When
all
will
purple
called
of
84).
discovered
plants
of
of
separation
looked
white
Mendel
there
dwarf.
the
(see
genes
as
dwarf
that
Alleles
the
consisted
dwarf
another
.
assortment
law
owers.
which
plants
and
‘blending’
he
with
purple
and
these
meiosis
when
plants
hybrid
these
produce
rst
two
generation
(tall
give
no
pea
stating
tall
the
self-
plants
dwarf.
to
when
plants
with
by
–
result
of
of
as
9 : 3 : 3 : 1,
pairs
from
independent
way
dwarf
for
is
the
example,
plants
the
is
inheritance
For
to
meiosis
anaphase
same
alleles
There
called
tall
results
allele
of
When
of
showed
plants
produce
tall.
order
always
pea
varieties
to
were
two
during
with
tall
the
independently
law
the
dwarf
consisted
segregation
only.
were
and
formation.
the
crossed
it
that
As
different
Mendel’s
over
during
self-pollinated
that
this
Mendel
investigated
one
and
separate
This
behaved
tall
explain
for
plants
generation
generation
gamete
alleles .
pea
generation.
crossed
e.g.
dominant
alleles
of
after
He
height
chromosome
means
the
We
alleles
phenotypes
segregated
law
92
in
lines
this
next
3 : 1.
generation
were
possible
the
in
generation.
owers
next
two
gene
inheritance
chromosome.
represents
chromosome
genes.
green
cells
bred
features,
during
Mendel
each
of
The
hybrid
When
characteristic
that
cone
inbred.
plants
must
identity
the
that
be
controls
has
homologous
Did you know?
the
that
inheritance.
of
can
ratio
segregation
show
are known
genetics
pure
alternative
individual
species.
Chromosomes
and
non-sex
protein for
generation
self-pollinated
plants
Did you know?
laws of
they
offspring.
species
chromosomes
clotting
44
A human X chromosome showing some of the gene loci
established
showing
different
in
characteristic
pollinate
of
male). The
this.
same
offspring
=
of
Mendel
term
in
sex
female
autosomes
protein for
Mendel’s
The
blood
protein
red
light
two
=
each
cone
haploid
IX
(XX
protein
XY
Link
chromosomes,
the
all
of
these
four
see
+
this
on
white)
his
second
Module
2
Genetics,
variation
Genetic diagrams
Genetic
diagrams
are
S tudy
used
to
show
how
the
genes
for
different
inherited.
These
should
be
set
out
clearly
so
that
teachers
The
rules
can
for
follow
your
making
reasoning;
genetic
you
diagrams
should
are
not
explained
take
any
short
1:
Each
not
Describe
gene
given
height,
Step
2:
There
the
controls
in
the
of
Identify
will
tell
description
a
or
these
on
be
at
diagrams
Make
sure
investigated
stem
and
that
you
genes
ower
state
that
this
control
3:
Choose
least
two
alleles
allele
genetic
symbols
if
it
a
capital
recessive
letter
allele.
codominance
superscripts
Step
The
4:
Give
Use
or
for
for
the
is
for
each
dominant
gene.
or
it
The
will
this
consisting
them
to
has
start
do
individual
two
this.
two
two
T
est
a
study
guide
and
in
obvious
from
letter
,
(see
not
then
each
96
alleles,
of
even
may
homozygous
a
if
lower
different
capital
and
the
denitions
genotype
on
of
page
phenotype
the
gene
they
recessive
letter
letters.
letter
for
If
for
there
the
the
the
is
studying
gene
and
one
in
control
or
a
narrow
90.
Here
sense
two features
and
the
gene
to
they
that
or
refer
we
genes
to
are
that
them.
parents.
concerned.
are
The
the
individuals,
involve
case
used
102).
of
the
a
chromosome.
homozygous
crosses
and
two
use
genotype
alleles
of
allele
pages
and
the
at
alleles.
alleles,
copies
of
with
with
same
of
this
Link
information
be
Look
dominant
alleles
consists
and
by
the
in
examination.
colour
.
cross.
the
phenotype
diploid
diagrams
the
multiple
the
genotype
for
when
genetic
is
are
Use
using
plant
and
Step
carefully
features.
which
the
the
steps
questions
concerned.
feature.
Mendel
allelic
you
of
genes
certain
owers
the
always
will
gene
question.
position
provided
the
foc us
cuts.
below.
your
Step
selection
and
answering
examiners
natural
features
Follow
are
and
same.
but
crossing
a
Each
genotype
do
cell
Some
not
is
reects
genetic
expect
all
of
heterozygous
individual.
Link
Step
5:
State
Gametes
number
.
are
two
all
the
Step
from
in
6:
Use
fusion
a
genotype,
Step
7:
not
the
gametes.
meiosis
be
one
to
of
one
down
square
at
of
will
down
gametes
each
the
genotypes
W
rite
write
Punnett
of
the
there
circle.
just
of
because
write
crosses
each
same
genotype
haploid
Always
monohybrid
be
the
the
letter
,
show
in
different
genotype
all
fertilisation.
actual
halving
gametes
in
the
This
numbers
of
a
the
If
chromosome
inside
circles.
dihybrid
types
of
crosses
there
gamete.
If
you
that
In
will
they
are
then
out
the
different
writing
sex
include
a
the X
chromosomes
genetic
linkage
in
as
diagram
on
page
97
and Y
the
genotypes.
circle.
possible
square
genotypes
gives
the
that
result
probability
of
S tudy
foc us
offspring.
Do
W
rite
are
shows
genotypes
and
give
the
phenotype
of
not
use
criss-cross
lines
to
show
each
the
possible
genotypes
as
it
is
easy
one.
to
Step
8:
answer
W
rite
as
a
out
the
probability
of
each
phenotype
and
express
make
mistakes
the
ratio.
Link
Sometimes
you
numbers
for
numbers
by
will
be
different
the
given
the
categories,
smallest
numbers
so
number
to
called
nd
of
offspring.
categoric
the
overall
Note
data.
that
Always
phenotypic
these
are
divide
You
will
see
on
pages
104
to
107
that
ratio.
a
statistical
categoric
test
is
applied
to
data.
Summary questions
1
Dene the following terms:
2
Explain
what
breeding
3
Explain
and
the
is
meant
by
autosome,
sex chromosome,
the following:
inbreeding,
haploid
and
interbreeding,
diploid.
cross
hybridisation.
terms
gene
and
locus.
93
3.3
Monohybrid
Learning outcomes
cross
Confirming
The
On
completion
of
this
section,
fruit
be
able
state
that
involves
a
the
monohybrid
inheritance
cross
of
the
Morgan
terms
as
to
located
dominant,
are
and
peas.
on
many
in
New
theories
segregation
ies
dene
century
Mendel’s
one
gene

Hunt
melanogaster ,
(1866–1945)
was
for
the
animal
studying
chosen
genetics
by
early
in
the
to:
20th

Drosophila
ratios
you
Thomas
should
y,
Mendel’s
Y
ork.
about
Morgan
inheritance,
independent
He
also
to
by
but
assortment
provided
chromosomes
advantages
originally
in
fact
out
he
applied
evidence
investigating
using
set
for
Drosophila,
as
one
that
that
(see
big
the
much
theory
linkage
but
disprove
found
just
the
sex
to
to
laws
genes
page
of
fruit
are
97).
There
disadvantage
–
it
recessive, homozygous and
ies!
In
spite
of
this
they
are
still
bred
for
use
in
schools
and
colleges
and
heterozygous
are

make
genetic
interpret
diagrams
monohybrid
used
in
research
In
a
population
In
Pure-bred
the
and
development.
fruit
of
ies
these
fruit
When
do
ies
male
some
not
with
and
emerge
survive,
small
female
from
but
in
wings
ies
pupae
and
from
with
captivity
long
these
very
they
small
do.
wings
were
pure-bred
lines
were
foc us
crossed
stages
of
wild
lines
established.
The
genetics
to
crosses.
wings.
S tudy
into
in
the
life
cycle
of
a fruit
the
together
offspring
three
all
quarters
had
of
long
them
wings.
had
When
long
these
wings
and
fruit
a
ies
quarter
were
had
bred
short
wings.
y
are
adult.
the
to
egg,
(maggot),
Metamorphosis
pupal
an
larva
stage
as
the
pupa
occurs
larva
and
during
changes
adult.
This
feature
protein
the
gene,
The
genetic
Take
care
foc us
over
represent
There
choosing
genes. You
letters
should
are
controlled
inuences
long
inheritance
S tudy
is
that
and
short,
diagram
of
two
one
alleles:
(w).
V
estigial
parental
phenotypes
–
a
with
known
shows
the
long
gene
development
are
below
gene
vestigial
by
the
gene
wing
means
a
(also
very
feature
too
letter
unless
similar
your
of
to
the
the
the
this
capital
coding
The
two
for
a
forms
of
alleles.
wing
cross
length
known
as
in
wild
involving
D.
the
melanogaster .
type)
( W)
and
small.
male
female
×
letter
wing
(wild
type)
vestigial
genotypes
parental
gametes
the
case
WW
wing
ww
looks
letter
might
parental
+
W
in
w
cause
choose
genotype
Ww
1
phenotype
F
another
DNA
choose
case
which
is
of
wings.
to
F
If
the
dominant
lower
handwriting,
confusion.
length
monohybrid
for
long
the rst
as
a
of
all
long
wing
(wild
type)
1
letter.
F
phenotypes
long
wing
×
long
wing
1
genotypes
F
Ww
Ww
1
Link
gametes
F
w
W
1
Look
back
genetic
to
the
diagrams
advice
on
on
page
w
W
,
+
,
making
male
93.
W
gametes
w
W
WW
Ww
w
Ww
ww
female
gametes
F
genotypes
and
phenotypes
WW
2Ww
ww
2
long
phenotypic
F
2
94
ratio
3
long
wing
wing : 1
long
wing
vestigial
wing
vestigial
wing
Module
The
checkerboard
or
Punnett
square
is
the
best
way
to
show
the
2
Genetics,
variation
the
that
next
the
generation
Punnett
–
even
square
when
shows
the
there
are
possible
few
genotypes
outcomes
–
involved.
the
represent
genotypes
During
actual
and
organisms.
phenotypes
meiosis
in
the
in
the
ies,
F
It
shows
next
the
the
probabilities
of
separation
gives
rise
gametes
is
to
segregation
variation
with
genotype
W
(WW),
homozygous
or
ies
that
of
since
w
to
a
F
alleles
pair
ies
are
and
F
1
lial
and
only
be
stand for rst
2
second lial. They
should
generation.
separate
separate
of
gametes
give
which
recessive
terms
different
because
they
are
used
during
alleles .
with
with
the
the
meiosis
Notice
allele
also
W
( Ww)
and
the
parental
are
homozygous.
This
that
can
homozygous
heterozygous
I.
when
on
individuals
chromosomes
foc us
do
1
homologous
selection
Note
genotypes
The
not
natural
genotypes
S tudy
of
and
fertilisation
fuse
with
dominant
ies
S tudy
which
foc us
are
( ww).
F
is
not
used
here
because
we
do
1
not
If
the
cross
is
carried
out
by
using
females
with
long
wings
and
know
the
ies. Only
with
short
shows
the
wings
that
the
(the
gene
chromosomes
reciprocal
for
that
wing
cross)
length
determine
Monohybrid test
is
the
same
not
results
linked
with
are
the
obtained.
use
with
we
the
know
which
recessive
inheritance
of
of
an
are
This
is
recessive,
characteristic
individual
involves
are
we
know
homozygous
that
all
an
individual
with
or
the
dominant
heterozygous.
crossing
that
recessive.
However
,
characteristic
could
male
fruit
y
homozygous
genotype
of
with
is
long
recessive.
the
the
of
to
the
be
foc us
the
test
cross
We
can
nd
out
by
the
individual
with
the
doing
unknown
homozygous
wings
The
is
also
be
done
a
showing
the
dominant
test
and
males
which
are
genotype
recessive. The
results
recessive.
crossed
genetic
could
be
would
A
of
individuals
homozygous
with
one
both
homozygous.
sex.
phenotype
cross.
of
if
cross
allele
dominant
F
2
known
with females
homozygous
and
1
parents
This
genotype
F
This
S tudy
Once
genotype
males
with
diagram
a
female
shows
how
that
to
be
the
same.
is
work
out
the
male.
Summary questions
phenotypes
male
female
×
long
wing
genotypes
(wild
type)
vestigial
–
W
wing
1
Explain
ww
allele,
gametes
+
–
W
the following
monohybrid cross,
terms:
dominant
recessive allele,
w
,
homozygous,
heterozygous
and
test cross.
male
gametes
2
Plants
rapa
but
female
w
gametes
Ww
–
offspring
offspring
genotypes
=
Ww
phenotypes
w
if
ww
50%
long
50%
short
–
=
Ww
wing :
all
some
Brassica
a
a
long
rosette
stem,
habit
stem
all. When
does
pure
not
in
bred
grow
long-
W
stemmed
plants
are
pure
rosette
crossed
with
Ww
long
(wild
grow
have
the
bred
plants,
all
the
wing
offspring
wing
species
w
at
–
the
normally
which
if
of
–
W
have
long
stems. When
type)
these
plants
are
interbred
three
explanation
quarters
If
all
the
offspring
have
long
wings,
then
the
gametes
that
have
of
the
–
as
must
have
the
dominant
allele,
some
must
of
have
the
offspring
the
recessive
have
short-wings,
allele,
then
the
gametes
given
as
them
fact,
if
any
short
winged
were
symbols
A for
passed
on
recessive
quarter
long
stem
the
and
w
ies
emerge
we
know
that
the
male
rosette,
alleles
and
he
must
be
draw
a
genetic
must
diagram
have
one
rosette. Using
–
a for
In
and
W
of
If
were
been
long-stemmed
given
offspring
to
explain
these
results.
heterozygous.
3
Use
how
a
genetic
you
genotype
plant
of
diagram
would nd
of
the
a
to
out
explain
the
long-stemmed
species
B. rapa.
95
3.4
Codominance
Learning outcomes
completion
of
this
section,
be
able
linkage
four
o’clock
plant
(Marvel
of
Peru),
Mirabilis
jalapa ,
has
three
you
different
should
sex
Codominance
The
On
and
ower
colours.
If
pure
bred
red-owered
plants
are
crossed
with
to:
pure
bred
white-owered
plants
then
the
plants
F
have
pink
owers.
1

dene
and

use
the
terms
codominance
They
sex linkage
genetic
problems
like
diagrams
involving
to
on
solve
codominance
and
sex
different
‘blending
peas.
next
as
are
either
inheritance’
However
,
generation
the
from
if
genotypic
that
these
gives
all
ratio
in
of
the
two
Mendel
parental
disproved
pink-owered
three
the
colours
plants
in
a
monohybrid
are
1 : 2 : 1
cross
phenotypes.
with
his
interbred
ratio.
on
page
This
looks
experiments
This
then
is
the
the
same
94.
linkage.
The
reason
contribute
as
for
to
the
the
codominant
intermediate
phenotype
alleles.
The
of
colour
the
alleles
(pink)
is
that
heterozygous
are
written
both
plants.
as
alleles
They
are
known
follows:
R
=
C
red
W
The
letter
C
represents
the
R
either
the
The
nor
genetic
o’clock
parental
white
gene;
the
.
This
alleles
indicates
are
represented
that
the
alleles
by
are
C
with
neither
recessive.
diagram
plant
=
W
or
superscript
dominant
C
shows
through
two
the
inheritance
of
ower
colour
in
the
four
generations.
phenotypes
red-owered
white-owered
×
plant
R
parental
genotypes
parental
gametes
answer
W
C
W
C
R
Link
Now
plant
R
C
C
W
C
Summary
question
2
to
C
+
R
F
genotype
C
W
C
1
see
the
results
of
a
test
cross
F
phenotype
all
pink
1
involving
codominant
alleles.
F
phenotypes
pink
×
pink
1
R
genotypes
F
C
W
R
C
C
W
C
1
F
Summary questions
gametes
R
W
C
1
R
+
C
1
Explain
term
what
is
meant
by
W
C
,
C
,
male
the
gametes
codominance.
R
W
C
2
A
pink-owered four
plant
was
crossed
C
o’clock
with
a
R
R
white-
C
C
R
R
C
C
W
C
female
owered
plant. Use
a
genetic
gametes
R
W
diagram
of
this
to
test
show
the
outcomes
R
One
of
the
blood
group
the
MN
genotypes
system. The
M
GYPA
codominant.
diagram
parents
group
with
to
N
and
Draw
show
who
MN
W
C
and
phenotypes
C
R
R
C
2C
both
may
different
GYPA
a
blood
W
C
phenotypic
ratio
1
red : 2
pink
pink :1
white
white
2
the
This
are
two
have
have
W
C
are
genetic
how
W
C
two
F
alleles,
W
C
2
systems
red
is
W
C
cross.
F
3
C
C
blood
children
groups.
shows
three
was
that
ower
dominant
Flower
colour
if
alleles
colours
to
the
allele
depends
Enzymes
catalyse
pigment.
The
are
not
the
on
codominant
two,
for
the
as
more
would
be
variation
the
case
if
appears
the
allele
as
there
for
red
white.
production
conversion
of
a
of
pigments
colourless
in
the
substance
petals.
into
the
red
R
State
the
probability
that
a
child
enzymes
coded
for
by
two
C
alleles
are
an
inactive
required
to
produce
W
could
inherit
each
of
the
blood
the
red
pigment.
The
allele
C
codes
for
enzyme.
Where
there
R
groups.
is
one
cells
96
C
to
allele
make
there
some
is
of
only
the
enough
red
enzyme
pigment
which
molecules
gives
the
produced
petals
a
in
pink
the
colour
.
Module
Sex
2
Genetics,
variation
and
natural
linkage
Males
Among
the
ies
in
Morgan’s
collection
were
some
that
had
rather
than
investigated
the
the
usual
wild
inheritance
of
type
eye
red
eyes.
colour
When
the
Females
white
genotype
eyes
selection
phenotype
genotype
results
did
red
X
not
R
X
match
the
prediction
that
there
would
be
a
3 : 1
phenotype
Morgan
ratio
in
the
R
Y
eyes
R
X
red
eyes
red
eyes
as
F
2
with
the
inheritance
of
wing
length.
r
X
When
pure-bred
white-eyed
female
fruit
ies
were
crossed
R
white
Y
eyes
X
r
X
with
r
X
pure-bred
red-eyed
red-eyed
as
red-eyed
and
and
no
When
might
all
male
have
the
white-eyed
this
fruit
been
males
the
next
predicted.
were
females.
generation
F
ies,
Instead
white-eyed.
The
were
generation
expression
crossed
the
all
the
There
of
eye
next
were
females
were
no
colour
white
eyes
were
red-eyed
had
generation
r
X
not
swapped
had
Note
males
sexes.

all
the
following
features
of
sex
linkage:
the
recessive
phenotype
is
1
combinations
of
sex
and
eye
colour
in
approximately
equal
more
numbers.
in
The
inheritance
of
this
gene
was
similar
to
the
inheritance
of
the
The
gene
for
eye
colour
is
on
the
X
chromosome.
equivalent
gene
on
the
Y
chromosome.
This
means
that
There
copies
of
this
gene
in
the
same
way
as
with
genes
that
females
have
males
cannot
autosomes.
their
Males
T
o
only
show
have
one
inheritance
copy
of
a
as
they
only
sex-linked
have
gene
it
one
is
parent,
females
can
the
X
and
Y
chromosomes
and
put
the
symbols
for
but
their
females
be
can
heterozygous
X
usual
therefore
the
carriers
of
the
to
condition,
include
the
from
loci
and
chromosome.
inherit
condition
have

on
than
is
male
two
males
females
recessive
no
in
X

chromosome.
common
alleles
males
can
never
be
as
carriers
superscripts.
The
table
shows
all
the
different
genotypes
for
the

inheritance
of
eye
colour
in
males
inherit
chromosome
Males
are
hemizygous.
chromosome.
These
They
alleles
chromosome
homologous
heterozygous
are
as
in
this
have
are
to
described
allele
always
their
as
one
X
of
each
expressed
as
chromosome.
carriers
when
the
of
the
there
genes
is
the
and
X
that
no
Females
mutant
on
which
allele
is
phenotypes
parental
genotypes
this
red-eyed
male
×
white-eyed
X
found
R
X
the
father
the
loci
X
foc us
female
a
question
says
that
males
and
r
of
a
certain
species
were
r
+
Y
on
have
X
females
gametes
not
their
chromosome.
are
If
r
Y
X
does
are
S tudy
R
parental
Y
from
recessive
example.
parental
their
Drosophila
X
crossed,
that
does
not
necessarily
,
mean
female
that
the
gene
involved
is
gametes
sex-linked. You
clues.
r
See
need
Summary
to
look for
question
other
6
X
below
R
R
X
X
male
and Question
7
on
page
109.
R
X
Summary questions
gametes
r
X
Y
r
F
genotype(s)
X
Y
R
Y
X
4
Explain
the
5
Explain
how
term
sex linkage.
r
X
sex
is
determined
in
1
F
phenotype(s)
white-eyed
male
red-eyed
fruit ies
female
and
in
humans.
1
r
genotypes
F
X
R
Y
×
X
r
X
6
1
F
gametes
r
X
1
R
+
Y
,
Suggest
why
sex
linkage
is
seen
r
X
in fruit ies
X
but
not
in
plants,
,
such
female
as
the four
o’clock
plant,
gametes
Mirabilis jalapa.
R
7
r
X
a
Find
out
about
inheritance
R
r
X
male
X
r
X
r
X
R
genotypes
and
phenotypes
X
and
Y
X
r
X
Y
haemophilia
in
colour
humans.
r
Y
R
X
of
red-green
blindness
R
F
r
X
gametes
Y
the
X
X
r
X
Y
r
X
b
Show,
using
how
man
a
a
genetic diagram,
cannot
inherit
r
X
haemophilia from
his father,
2
red-eyed
white-eyed
red-eyed
white-eyed
male
male
female
female
but
can
pass
it to
his
grandson.
97
3.5
Dihybrid
cross
So
Learning outcomes
far
we
have
Humans
On
completion
should
be
able
of
this
section,
about
you
ies

state
that
dihybrid
the
at
have
about
and
the
at
the
20 000
the
genes
number
inheritance
four
inheritance
different
of
in
that
B.
two
of
code
rapa
genes.
chromosomes,
one
is
for
gene
proteins,
43 000.
Y
ou
that
with
Let’s
might
there
two
fruit
start
predict
are
alleles.
ies
that
about
have
with
since
4000
fruit
genes
on
inheritance
each
involves
have
14 000
looking
to:
looked
inheritance
of
and
that
the
inheritance
pattern
will
not
be
simple.
two
genes
Dihybrid

use
genetic
inheritance
controlled

explain
diagrams
of
by
how
to
show
two features
separate
to
use
a
genes
test
cross
in
Wild
type
have
short
crossed
context
of
a
dihybrid
identify
phenotypic
ies
wings
and
all
have
and
the
long
black
wings
bodies.
offspring
had
and
Pure
the
grey
bodies.
bred
wild
ies
type
of
There
both
are
some
types
phenotype.
that
were
were
crossed
all
combinations
of
features
appeared
When
in
the
these
F
offspring,
cross
in

fruit
1
ies
the
cross
the
the
following
numbers:
ratios.

wild
type
(long
wings

long
wings

short
wings
and
grey

short
wings
and
black
and
black
and
grey
body,
body),
650
198
Did you know?
One
of
the
chromosomes
Drosophila
is
so
small
in
that
the
genes
are found
chromosomes
on
three
not four.
the
approximates
ratio
When
the
you
foc us
see
smallest
number
like
this,
into
the
long
to
have
segregated
The
results
of
body
black
different
S tudy
225
body,
68.
most
This
of
body,
to
a
wings
body
is
ratio
to
also
of
9 : 3 : 3 : 1.
short
wings
about
independently
3 : 1.
of
is
But
This
one
if
about
you
3 : 1
suggests
another
and
look
and
that
are
give
should
that
the
be
you
phenotypic
close
to
will nd
one
in
ratio.
of
this
the
can
ratio
the
two
therefore
see
of
that
grey
genes
on
chromosomes.
genetic
diagram
involves
the
parental
phenotypes
shows
inheritance
of
what
two
happens
in
this
dihybrid
cross
which
genes.
divide
wild
type
male
×
female
with
short
wings
others
and
to
you
the
black
body
It
parental
genotypes
parental
gametes
WWGG
wwgg
ratios
wg
WG
chapter.
+
F
genotype(s)
WwGg
1
phenotype(s)
F
all
long
wings
and
black
body
1
genotypes
F
WwGg
×
WwGg
1
gametes
F
Wg
WG
1
,
wG
WG
,
wg
wG
,
This
is
combined

square
shows
produced
effects
meiosis
that
with four
by
98
wG
wg
the
WG
WWGG
WWGg
WwGG
WwGg
Wg
WWGg
WWgg
WwGg
Wwgg
wG
WwGG
WwGg
wwGG
wwGg
wg
WwGg
Wwgg
wwGg
wwgg
of:
produces
different
fertilisation
combine
gametes
how
gametes
male

wg
foc us
Punnett
variation
,
,
female
S tudy
Wg
,
when
gametes
genotypes
these
randomly.
gametes
Module
F
genotypes
2
Genetics,
variation
and
natural
selection
and
2
genotypes
phenotypes
WWGG
long
WWGg
grey
proportions
S tudy
foc us
phenotypes
1
__
wing,
16
Working
2
__
out
the
genotypes
in
the
F
2
body
16
9
__
should
show
you
why
using
a
16
2
__
WwGG
16
Punnett
square
is
so
useful.
Do
not
4
__
WwGg
use
16
criss-cross
lines for
this.
1
__
long
WWgg
wing,
black
Wwgg
16
3
__
2
__
16
body
16
1
__
short
wwGG
grey
wwGg
wing,
16
3
__
2
__
16
body
16
short
wwgg
black
F
phenotypic
ratio
9
long
wing,
grey
1
__
1
__
16
16
wing,
body
body : 3
long
wing,
black
2
body : 3
black
The
Punnett
square
shows
that
short
wing,
grey
body : 1
short
wing,
body
there
S tudy
are
nine
different
genotypes,
but
Figure
because
of
dominance
there
are
only
four
different
phenotypes
in
9 : 3 : 3 : 1,
which
approximates
to
the
numbers
given
3.5.
1
shows
called
this
independent
assortment ,
which
of
two
means
that
the
segregate
in
meiosis
independently
of
one
another
.
This
is
are
on
different
chromosomes.
Y
ou
can
see
this
in
Figure
3.5.1
some
pairs
you
can
use
chromosome
models
to
model
this
(see
page
the
metaphase
the
maternal
chromosomes
on
align
I.
and
will
align
as
the
as
left
on
and
the
in
others
right. There
they
is
a
B
50%
chance
maternal
a
that
paternal
chromosomes
and
will
align
in
b
each
B
metaphase
a
B
A
b
of
these
ways.
I
b
a
on
during
and
will
A
homologous
87).
shown
A
of
aligning
plate
cells
paternal
also
a
because
In
they
as
two
equatorial
genes
happens
opposite.
chromosomes
Mendel
what
the
result
ratio
foc us
Summary questions
a
A
B
B
1
Explain
the
meaning
of
the
a
B
B
anaphase
a
terms
I
and
b
A
b
dihybrid inheritance
independent assortment.
b
b
a
A
2
B
B
B
Brassica rapa
green
A
a
A
plants
a
The
leaves
or
allele for
yellow
green
dominant. Use
anaphase
have
either
B
leaves.
leaves
genetic
is
diagrams
II
to
show
the
outcomes
in
the
F
1
a
a
A
A
and
F
if
a
pure
bred
plant
with
2
long
b
stems
crossed
telophase
a
a
3
A
B
b
green
leaves
is
with
a
rosette
plant
with
II
yellow
A
and
b
b
The
leaves.
Punnett
square
shows
B
that
there
genotypes
are
in
nine
the
different
F
of
the
2
dihybrid
Figure 3.5.1
cross.
Suggest
how
it
Independent assortment of the alleles of two genes, A/a and B/b
would
a
be
possible
dihybrid
those
cross
so
genotypes
to
carry
that
had
a
out
each
of
different
phenotype.
99
Module
2
Genetics,
variation
and
natural
selection
The
y
next
that
genetic
is
parental
diagram
heterozygous
shows
for
both
phenotypes
what
gene
wild
happens
in
a
test
cross
on
a
fruit
loci.
type
male
female
with
short
×
wings
parental
genotypes
parental
gametes
and
WwG
Wg
WG
Link
you nd
wG
,
difcult
independent
concept
to
assortment
understand,
body
wwgg
,
,
female
If
black
gametes
a
use
wg
the
chromosome
recommended
attach
alleles
sticky
of
referring
the
to
models
on
page
labels
two
87
and
show
genes
Figure
S tudy
to
WG
WwGg
Wg
Wwgg
wG
wwGg
wg
wwgg
the
while
3.5.
1.
male
gametes
foc us
Remember
that
there
probability
that
two
is
a
offspring
50%
and
pairs
genotypes
genotypes
phenotypes
WwGg
long
proportions
phenotypes
1
of
wing,
grey
body
4
homologous
chromosomes
will
align
1
long
Wwgg
themselves
with
the
on
the
metaphase
dominant
alleles
of
wing,
black
body
plate
the
4
1
two
short
wwGg
wing,
grey
body
4
genes
together.
1
short
wwgg
wing,
black
body
4
offspring
S tudy
foc us
The
You
must
state
a
phenotypic
ratio
null
ratio
1 : 1 : 1 : 1
to
you
analyse
use
the
your
long
1
short
the
wing,
grey
body : 1
wing,
grey
cross
ratio
test
body,
for
a
long
1
wing,
short
black
wing,
dihybrid
body :
black
cross
body
with
hypothesis
dominance
before
is
1
chi-squared
at
each
gene
locus.
test
If
data.
you
good
cannot
to
try
dihybrid
There
data
any
crosses
are
for
do
some
free
you.
monohybrid
Monohybrid
practical
computer
to
generate
simulations
dihybrid
cross.
F
some
with
data
available
Alternatively,
and
genetics
simulations
you
can
or
of
on
use
living
model
your
the
organisms
it
is
and
own.
internet
this
then
monohybrid
simple
that
way
will
to
generate
simulate
crosses.
T
ake
200
beads,
100
of
one
colour
and
100
of
a
1
different
colour
.
These
represent
the
alleles
from
50
F
individuals
that
1
are
heterozygous.
(Anything
suitable
will
do
in
place
of
beads.
But
they
Summary questions
must
all
touch.)
4
Describe
why
the
dihybrid
F
be
the
Decide
same
size
which
and
colour
shape
is
so
you
dominant
cannot
and
tell
predict
them
the
apart
result
by
that
you
ratio
2
will
expect
in
the
’.
‘F
Devise
a
table
to
record
the
results.
Place
all
the
2
is
9 : 3 : 3 : 1
whereas
the
test
cross
beads
ratio
is
in
colours
5
The
results
never
as
ratios.
a
bag
and
shake
them
up.
Remove
two
beads
and
record
the
1 : 1 : 1 : 1.
of
these
exactly
Suggest
crosses
predicted
why
this
is
are
by
the
the
case.
of
genotype
another
a
the
and
pair
you
Each
phenotype.
of
transparent
When
beads.
beads.
pair
of
Replace
Y
ou
must
beads
the
pick
represents
beads
the
in
the
beads
at
a
genotype.
bag,
shake
random,
so
Record
and
do
the
pick
not
use
bag!
have
50
offspring’,
‘F
total
the
numbers
of
each
genotype
and
2
6
Make
on
a
table
page
73
similar
to
show
to
the
the
phenotype.
Record
104)
if
genes
can nd
in
carry
out
a
chi-squared
test
(see
page
one
on
the
maps
internet.
of
to
see
your
Dihybrid
colours
bag
100
and
the
difference
predicted
result
is
between
the
signicant
observed
or
results
(phenotypes)
not.
D. melanogaster. You
chromosome
Drosophila
totals
effects
and
of
the
cross.
with
(gene
1)
Repeat
100
and
the
beads
put
of
the
same
each
other
procedure
colour
.
two
Put
colours
but
two
in
use
of
four
the
another
different
colours
bag
into
(gene
one
2).
Module
T
o
make
the
genotype
of
each
offspring
pick
two
beads
from
each
2
bag.
S tudy
Record
the
respective
genotype
bags
and
and
pick
phenotype
again.
Y
ou
and
then
could
return
make
this
the
beads
more
to
interesting
by
Read
having
codominance
at
one
of
the
gene
this
table
back
this
to
guide
the
and
should
given
in
a
relevant
In
each
case
make
pages from
sure
you
ratios
understand
Y
ou
carefully.
loci.
go
Genetic
foc us
their
be
able
to
question.
identify
This
genetic
table
Ratio
Description of the
3 : 1
F
from
a
ratios
should
help
from
the
results
that
you
this
are
the
descriptions
Page
cross
in
you.
cross
monohybrid
given
table.
with
dominance;
the
parental
generation
was
homozygous
number
94
2
1 : 2 : 1
F
from
a
monohybrid
cross
with
codominance;
the
parental
generation
was
96
2
homozygous
1 : 1
offspring from
9 : 3 : 3 : 1
F
from
a
a
monohybrid
dihybrid
cross
with
test
cross
with
dominance
at
‘unknown’
both
loci;
being
the
heterozygous
parental
95
generation
was
99
2
homozygous for
1 : 1 : 1 : 1
offspring from
dominance
1 : 1 : 1 : 1
F
from
a
a
at
both
dihybrid
both
cross
gene
loci
test
cross
with
‘unknown’
being
heterozygous
at
both
loci;
100
loci
involving
sex
linkage
where
the females
of
the
parental
generation
were
97
2
homozygous
recessive
and
the
males
were
hemizygous
dominant
S tudy
Summary questions
7
Usually,
purple
‘cut’
The
four
tomato
pigment
leaves,
table
is
but
Parental
have
missing
some
shows
separate
plants
the
purple
and
have
of
stem
so-called
numbers
crosses
the
stems,
and
tomato
is
although
green.
’potato’
in
Most
cut
plants
have
of
Remember
to
offspring,
resulting from
write
out
the
diagrams for Questions
full, following
Number
and
stem,
page
the
2
genetic
and
7
instructions
in
on
93.
phenotypes of offspring
cut
purple
leaves
stem,
tomato
the
plants.
phenotypes
purple
varieties
leaves.
phenotypes
purple
1
some
foc us
leaves
potato
stem,
leaves
green
stem,
leaves
cut
green
stem,
potato
354
0
367
0
693
241
0
0
60
71
56
67
leaves
×
green
2
stem,
purple
potato
stem,
cut
leaves
leaves
×
green
3
stem,
purple
cut
stem,
leaves
potato
leaves
×
green
4
stem,
purple
cut
stem,
leaves
cut
leaves
323
101
308
109
×
green
stem,
a
Calculate
b
Identify
alleles
c
Use
the
the
of
cut
genetic
genes
each
genetic
leaves
ratio for
involved
and
gene. Choose
diagrams
to
each
of
these
explain
suitable
explain
the
the
crosses.
relationship
symbols for
results
of
the
each
between
the
alleles.
of
the
crosses.
101
3.6
Interactions
Learning outcomes
Multiple
So
On
completion
of
this
between
section,
far
we
be
able
state
that
than

two
explain
of
some
genes
alleles
the
genes
state
have
(multiple
inheritance
with
that
multiple
more
alleles)
patterns
alleles
more
group
The
are
looked
at
dominant
than
locus.
gene
genes
at
different
interact
to
control
phenotypic feature
two
The
genes
and
with
two
recessive
the
antigens
experimental
alleles.
gene
controls
called
or
alleles.
have
The
been
pairs
of
of
locus
is
on
they
antibodies.
if
red
are
If
are
three
of
antigens
cells
from
detected
red
alleles
chromosome
production
because
animal
There
blood
as
9
on
one
of
are
the
the
the
solve
problems
and
human
blood
are
sometimes
why
blood
involving
The
gene
another
they
must
be
stimulate
typed
the
before
a
same
blood
response,
but
transfusion
is
not
always.
carried
is
locus
is
known
as
I
and
it
has
three
alleles,
I
B
,
O
I
and
I
A
.
I
codominant
and
both
are
dominant
to
I
.
There
are
six
and
genotypes
four
phenotypes
individual
two
can
copies
of
as
shown
only
have
in
the
two
chromosome
of
9
table
on
these
in
each
the
alleles
left.
as
humans
are
diploid
cell.
Phenotype
The
genetic
diagram
shows
how
a
man
who
has
blood
group
A
and
a
A
I
A
blood
group A
woman
who
parental
O
has
blood
group
B
can
have
phenotypes
children
with
blood
blood
group AB
blood
group
parental
genotypes
parental
gametes
A
blood
group
O
B
I
I
I
A
O
I
B
I
B
+
I
B
O
I
O
I
I
,
,
B
male
B
groups.
female
group
A
B
I
B
four
×
blood
A
all
male
I
I
This
out.
epistasis.
Genotype
I
human
O
are
with
I
an
the
multiple
Any
A
They
into
(epistasis)
and
I
cells.
injected
into
blood
genome.
stimulate
injected
B
and
genes
ABO
a
I
alleles
have
Many
human
red
person
‘foreign’
cells
at
A

alleles
codominant.
loci
then
may
alleles
have
been
production

genes
to:
have

and
you
either
should
alleles
gametes
O
I
I
A
O
I
I
,
O
I
O
I
blood
group O
B
A
I
female
I
O
probability
having
blood
a
baby
groups
regardless
children
O
I
A
O
I
I
B
O
O
I
O
I
foc us
A
The
B
I
gametes
I
S tudy
B
I
of
of
with
is
any
1
blood
they
parents
one
always
the
that
these
in
of
genotypes
I
offspring
phenotypes
O
I
blood
4
of
already.
The
give
phenotypic
the
there
of
is
ratio
probability
a
these
0.25
blood
is
of
(25%
A
I
group
groups
have
the
offspring
a
or
1 : 1 : 1 : 1.
child
1
in
In
I
blood
A
group
human
inheriting
4)
B
I
probability
blood
that
a
I
blood
AB
group
genetics
these
O
I
it
is
child
blood
B
group
more
groups.
will
O
I
In
usual
this
have
any
O
to
family
one
groups.
Did you know?
Epistasis
Blood
get
typing
given
during
a
is
essential
blood
of
the
transfusion.
so
people
same
In
group
Some
features
blood
group.
there
is
shortage
of
with AB
blood
these
can
or
of
any
other
genes
more
gene
groups;
type O
can
be
given
safely
blood
that
although
group
must
there
systems
be
tested
are
(e.g.
as
will
gene
as
is
controlled
the
by
case
more
with
the
than
one
ABO
interact
with
each
other
.
Epistasis
is
the
gene.
interaction
loci
in
the
control
of
a
phenotypic
feature.
The
of
genes
show
In
independent
such
cases,
assortment
however
,
the
if
they
are
phenotypic
on
different
ratios
expected
with
independent
assortment
(see
page
are
different
99).
other
Rhesus)
well.
those
Flower
as
the
colour
in
pigment
reactions
102
one
are
to
to
everyone,
by
that
blood
chromosomes.
of
only
features
receive
involved
blood
are
blood,
two
people
controlled
emergencies,
Often
when
are
There
blue-eyed
which
catalysed
by
Mary,
gives
the
Collinsia
petals
enzymes.
their
parviora ,
colour
is
is
a
good
produced
example,
by
Module
In
C.
on
parviora
the
there
are
two
such
reactions
that
occur
in
series
as
2
Genetics,
variation
and
shown
natural
white
selection
precursor
Enzyme
1
is
coded
by
the
gene
A/a
and
enzyme
2
is
coded
by
the
gene
B/b.
pigment Y
If
the
substance
right.
genotype
owers
matter
are
of
blue.
whether
produced
and
the
In
In
converted
to
not
9 : 3 : 3 : 1
a
plants
and
phenotype
that
the
has
that
2
owers
produced.
give
plants
enzyme
the
Z
plant
is
are
allele
will
in
blue-owered
genotypes
or
If
A
not
as
allele
but
have
the
alleles
homozygous
white.
plant
as
are
present
have
ratio
dominant
of
is
magenta
present
plant
bb,
on
×
then
Y
not
not
will
will
cross
(magenta)
the
does
will
Y
This
page
then
it
Y
then
owers.
cross
aa,
substance
recessive,
dihybrid
genes
recessive,
the
A
both
be
be
pigment
not
be
does
Figure 3.6.1
Z
(blue)
These two enzymes catalyse
reactions to produce a ower pigment
99.
blue-owered
AaBb
plant
AaBb
+
gametes
Ab
AB
aB
,
ab
,
AB
Ab
,
aB
,
female
ab
,
,
gametes
,
male
offspring
AB
A ABB
A ABb
AaBB
AaBb
Ab
A ABb
A Abb
AaBb
Aabb
aB
AaBB
AaBb
aaBB
aaBb
ab
AaBb
Aabb
aaBb
aabb
gametes
genotypes
and
phenotypes
genotypes
phenotypes
A ABB
blue
proportions
1
__
16
2
__
Summary questions
A ABb
16
9
__
2
__
16
AaBB
16
1
Dene
the
terms
multiple alleles,
4
__
AaBb
epistasis,
16
1
__
recessive epistasis
and
dominant epistasis.
magenta
A Abb
16
3
__
2
__
16
2
Aabb
A
couple
are
blood
group
B
16
and
1
__
blood
group A. Use
genetic
white
aaBB
16
diagrams
2
__
4
__
16
16
to
predict
the
blood
aaBb
groups
of
their
children.
1
__
aabb
16
3
Suggest
surface
offspring
phenotypic
blue : 4
white : 3
A
and
B
are
needed
to
produce
blue,
but
in
A-bb
magenta
as
no
are
functioning
enzyme
2
is
made.
But
when
no
there
are
alleles
blood
expressed
in
cells
that
( aa),
neither
B
(to
give
blue)
nor
b
(to
give
nuclei.
Draw
a
genetic
diagram
to
only
predict
recessive
cell
red
is
4
produced
on
magenta
have
Both
genes for
ratio
cells
9
how
antigens
magenta)
the
results
of
crossing
is
a
magenta-owered
plant
expressed.
of
In
this
example
the
gene
A/a
is
epistatic
over
gene
B/b
since
if
C. parviora
is
aa
(homozygous
recessive)
gene
B/b
cannot
be
An
B/b
is
said
epistatic
perhaps
enzyme.
by
where
type
since
each
be
is
there
gene
the
may
inhibiting
This
variation,
to
gene
hypostatic
also
its
act
locus.
one
controls
a
as
or
by
dominant
less
This
inhibiting
transcription
known
is
by
is
recessive
action
coding
for
epistasis .
phenotype
different
the
feature
you
an
gene,
inhibitor
with
saw
recessive for
both
on
loci.
epistasis .
another
Epistasis
compared
as
of
plant
expressed.
gene
Gene
a
the
homozygous
genotype
with
of
an
reduces
the
situation
page
5
What
effects
epistasis
have
on
Explain
and
do
dominant
recessive
phenotypic
your
epistasis
variation?
answer.
99.
103
3.7
Chi-squared
If
Learning outcomes
test
you
carry
out
inheritance,
On
completion
should
be
able
of
this
section,
have
you
the

Analyse
the
results
of
a
developed
the
null
results
this
that
matter?
chi-squared
differences
test
run
a
computer
exactly
In
as
between
a
1900,
t
any
Karl
‘goodness
observed
of
the
Pearson
of
and
simulation
t’
ratios
we
(1857–
test
expected
on
to
check
results
using
categoric
data.
completing
a
chi-squared
leaves
have
shaped
indented
like
leaves,
those
of
known
potatoes.
as
Pure
‘cut’.
bred
Some
tomato
tomato
plants
plants
with
test
cut
a
plants
hypothesis
have
in
the
of
gain
Does
or
by:
stating

not
far
.
experiments
genetic
T
omato

will
so
signicance
when
cross
you
obtained
1936)
to:
breeding
leaves
and
purple
stems
were
crossed
with
pure
bred
plants
with
table
potato
leaves
and
purple
stems.
green
stems.
All
the
generation
F
had
cut
leaves
and
1

using
a
probability
table
to
These
plants
F
were
test
crossed
against
tomato
plants
1
assess
the
signicance
of
the
showing
test
results.
the
cross
four
recessive
offspring
phenotype
showed
the
–
potato
following
leaves
and
numbers
of
green
stems.
plants
in
The
each
of
phenotypes:
purple,
cut
purple,
potato
green,
cut
green,
potato
Link
70
The
type
studies
is
is
of
because
you
individuals
such
as
data
called
in
collected
categoric
count
the
different
green,
cut
and
in
genetic
data. This
number
of
more
about
this
on
of
such
different
phenotypes
as
this
is
to
form
expected
1 : 1 : 1 : 1
chromosomes
I
the
86
and
in
the
assuming
test
that
independent
gametes
of
the
77
cross
the
offspring
two
assortment
genes
has
of
are
a
dihybrid
on
happened
during
plants.
F
1
potato.
The
Read
ratio
cross
meiosis
categories,
purple
The
91
page
null
hypothesis
is
the
hypothesis
that
states
there
is
no
signicant
124.
difference
between
the
observed
and
expected
results.
2
The
chi-squared
signicantly
test
(χ
different
)
is
from
used
the
to
nd
out
expected
if
these
results
are
results.
2
The
formula
for
calculating
is:
χ
2
(O–E)
______
2
χ
=


O
E
=
=
=
The
S tudy
You
the
can nd
you
may
squared
set
out
be
test
the
to
test for
you
to
observed
expected
gures
value
value
are
put
Categories
programs
asked
E
of….
into
this
table.
2
foc us
chi-squared
sum
do
should
calculation
carry
you,
a
this
purple
cut
purple
potato
E
O−E
2
(O−E)
(O−E)
70
81
−11
121
1.49
91
81
10
100
1.23
86
81
5
25
0.31
77
81
−4
16
324
324
/E
as
chi-
learn
in
out
but
O
how
to
green
cut
green
potato
table.
0.20
2
totals
χ
=
3.23
2
The
is
statistic,
signicant
shows
104
how
χ
or
to
,
has
not,
do
the
we
this.
value
need
of
to
3.23
look
in
at
a
this
example.
table
of
T
o
nd
probabilities.
out
if
This
this
table
Module
2
2
Degrees of
Distribution of
S tudy
χ
foc us
freedom
←
increasing values of
p
decreasing values of
p
→
In
the
the
probability,
exam
top
half
you
of
would
this
only
table
as
be
given
the
p
bottom
half
tells
you
how
to
2
0.99
0.90
0.50
0.
10
0.05
0.02
0.01
0.001
1
0.00016
0.016
0.46
2.71
3.84
5.41
6.64
10.83
2
0.02
0.21
1.39
4.61
5.99
9.21
13.82
3
0.
12
0.58
2.37
6.25
7
.82
interpret
the
S tudy
7
.82
The
9.84
11.35
table
in
similar
0.30
1.06
3.36
7
.78
9.49
11.67
13.28
0.90
result
p
is
‘dodgy’
T
o
>
use
are.
=
too
page
=
greater
the
In
126).
freedom
5%
of
The
p
not
3.23,
expected
outcome
outcome
we
is
=
was
less
need
has
to
or
cut
in
is
different
hypothesis.
arbitrar y,
but
is
as .
the
ever y
this
p
<
will
be
the
one
on
page
be
on
this
calculate
one from
the
the
and
page. To
107
,
the
df
number
use
not
by
of
the
subtracting
categories
in
0.001
highly
very
signicant
signicant
degrees
using
leaves
This
a
of
tally
there
freedom
chart
are
represents
table
at
20
times
7.82
critical
from
df
highly
table
critical
value
remember
at
to nd
the
p = 0.05
(df)
there
(see
three
the
we
value,
the
other
degrees
is
will
out
the
which
to
you
we
car r y
expected
accepted
until
that
which
decision
the
3
probability
at
The
now
many
plants
potato
the
intersect
than
0.01
you
will
of
3.
across
This
once
and
is
how
the
scored
case
read
row
less
know
score
be
<
probabilities
examination
than.
to
you
0.05.
and
null
=
this
signi cantly
the
<
could
in
is
is
expected
it
time
result
p
different from
plant
step
for
the
accept
5%
a
column
result,
is
If
0.05
signicantly
example,
that
not
<
different from
than;
which
next
column
is
p
signicantly
table
this
categories
The
0.05
result
good!
Note:
>
the
to
one
table,
>
foc us
18.47
the
p
χ
16.27
given
4
of
values for
the
means
value
a
the
result
value .
that
and
the
Our
result
we
can
of
0.05
probability
in
to
this
investigation.
critical
outcome
use
come
get
or
biological
investigations.
It
is
more
than
and
0.5.
50%
random
precise
The
to
say
that
probability
which
means
fertilisation.
of
value
getting
that
The
the
the
of
this
result
difference
is
greater
result
is
is
p
due
not
is
to
than
therefore
chance
statistically
0.1
and
less
between
effects
such
significant
10%
Link
as
and
so
Autosomal
means
that
the
gene
2
the
null
critical
is
a
hypothesis
value
significant
prediction
to
then
see
if
Curled
is
wings
bristles
are
and
any
between
or
of
If
the
the
value
results
observed
the
for
is
and
is
χ
less
greater
than
expected.
experimental
0.05
If
so,
procedure
is
than
and
the
there
locus
sex
is
on
an
autosome
chromosome
(see
and
page
not
on
92).
the
reviewed
errors.
spineless
crossed
bristles.
accepted.
rened
Pure-breeding
were
spineless
be
probability
difference
rejected,
there
Drosophila.
can
the
with
The
bristles
wild
autosomal
ies
pure-breeding
all
F
are
type
had
with
ies
straight
recessive
straight
with
wings
curled
and
features
wings
and
wings
normal
in
normal
and
bristles.
1
Female
ies
from
the
were
F
test-crossed
with
males
homozygous
for
1
both
gene
loci.
The
results
were
as
follows
overleaf.
105
a
Module
2
Genetics,
variation
and
natural

S tudy
selection
straight
bristles
Draw
a
table
like
that
on
page
104
to

curled
of
how
to
derive
the
value for
=
normal
bristles
=
186;
straight
wings,
spineless
18;
wings,
normal
bristles
=
16;
curled
wings,
spineless
bristles
=
180.
2
show
wings,
foc us
χ
275.76.
The
ratio
The
null
observed
of
phenotypes
hypothesis
and
is
expected
that
expected
in
there
is
a
cross
no
such
as
signicant
this
is
1 : 1 : 1 : 1.
difference
between
the
results.
2
The
It
value
is
for
obvious
observed
is
χ
that
calculated
the
numbers
as
275.76.
chi-squared
are
so
value
different
is
from
going
the
to
be
expected
large
because
numbers.
the
Putting
2
the
χ
value
of
these
is
much
can
less
reject
assort
of
than
the
1
you
are
is
is
it
the
3
W
rite
a
number
the
Link
Try
doing
own
chi-squared
data from
pages
5
the
tests
on
simulation
do
a
df
and
are
on
=
by
is
conclude
be
the
on
3,
we
chance
such
a
same
see
that
from
low
that
the
the
probability
expected
probability
these
different
chi-squared
two
that
genes
chromosomes.
chromosome,
is
of
Complete
what
hypothesis.
This
always
in
ratio
we
do
not
The
likely
fact
table
six,
of
among
the
type
that
has
are
of
the
steps
inheritance
you
follow.
pattern
there
etc.
not
starts
been
‘there
done
is
no
for
you.
signicant
…’
always
as
but
data.
the
row
table
shown
the
For
is
on
page
number
a
offspring
phenotypes
(One
these
sex-linked,
if
four
table.
see
ratio
classes
with
to
dihybrid,
test,
expected
between
phenotypes
your
to
chi-squared
columns
cross
they
at
This
cannot
information
null
difference
Draw
and
monohybrid,
Determine
4
table
(0.1%).
hypothesis
that
2
a
the
signicantly
3.
asked
Analyse
is:
0.001
null
chromosome
into
departing
independently
explanation
If
275.76
results
104.
rows
monohybrid
you
among
needed
of
for
need
the
the
The
number
depends
cross
three
offspring
headings
with
rows;
you
of
on
two
for
a
need
the
of
the
dihybrid
ve
rows
in
columns.)
by:
a
calculating
the
expected
b
calculating
the
difference
c
squaring
d
dividing
results
using
the
predicted
ratio
your
between
observed
and
expected
results
on
100–101.
each
the
the
class
difference
square
(this
of
takes
(to
the
into
remove
signs)
difference
by
the
consideration
expected
the
size
of
numbers
the
for
sample)
2
e
adding
f
deciding
g
nding
up
the
on
the
the
identifying
i
checking
of
degrees
0.05
appropriate
h
results
the
of
nal
column
freedom
probability
( p)
in
to
give
(number
the
table
of
of
the
statistic,
classes
−
χ
1)
probabilities
for
the
df
the
critical
value
2
to
see
if
the
χ
value
is
greater
or
less
than
the
critical
value.
If
it
is
less
expected
If
is
it
and
greater
expected
expected
less
probability
106
then
and
of
there
results
then
no
there
results
than
is
and
and
once
getting
is
a
the
in
the
signicant
the
null
difference
hypothesis
signicant
null
20.
by
between
your
chance,
is
between
rejected.
conclusions
e.g.
the
predicted
accepted.
difference
hypothesis
Express
result
is
p
<0.1
the
The
in
but
predicted
result
terms
>0.05.
can
of
the
be
Module
2
Genetics,
variation
and
natural
selection
Summary questions
2
1
The
results
of
certain
types
of
experiments
can
5
What
does
6
What
is
7
What
does
8
What
do
the
χ
value
mean?
2
be
analysed
with
experiments
the
have
in
χ
test
–
what
do
these
the
importance
of
the
5%
level
(or
0.05)?
common?
p
stand for?
2
2
What
3
Given
type
of
data
can
be
analysed
using
the
χ
test?
you
conclude
if
the
value for
p
is
greater
if
the
value
of
p
is
less
if
the
value
of
p
is
greater
the formula:
than
2
(>)
0.05
(5%)?
(O–E)
______
2
χ
=

what
are
the
row
and
E
column
9
headings
in
the
What
(<)
table
do
0.05
you
conclude
than
(5%)?
2
for
calculating
χ
?
10
4
In
How
do
questions
you
11
calculate
to
13
you
degrees
should
What
of freedom?
use
this
table
than
of
probabilities for
the
do
(>)
you
0.9
conclude
(90%)?
chi-squared
test.
2
Degrees
distribution of
χ
of
probability,
freedom
1
p
0.90
0.50
0.
10
0.05
0.02
0.01
0.02
0.46
2.71
3.84
5.41
6.64
0.001
10.83
S tudy
2
0.21
1.39
4.61
5.99
7
.82
9.21
foc us
13.82
Make
sure
you follow
instructions
3
0.58
2.37
6.25
7
.82
9.84
11.35
11
1.06
A
student
type
(long
3.36
investigated
7
.78
inheritance
winged) fruit ies. All
9.49
11.67
in fruit ies. The
the
F
fruit ies
13.28
student
were
long
F
you
18.47
crossed
some
winged. The
F
1
the
this
section
when
16.27
using
4
in
the
vestigial
ies
the
have
table. The
the
more
better!
winged fruit ies
were
practice
interbreed
with
with
these
some
wild
results
in
1
generation:
2
long
a
winged
State
164
the
vestigial
phenotypic
expect for
the
F
ratio
that
the
winged
student
36
c
should
Use
results.
the
to nd
chi-squared
if
the
results
test
of
and
this
the
cross
table
differ
of
probabilities
signicantly
or
2
b
Give
the
null
hypothesis for
this
not from
investigation.
d
12
Plants
of
Marvel
Pink-owered
red-owered
pink-owered
Use
your
the
Show
13
Another
plants
The
F
of
results
red,
amongst
white
or
this
can you
make from your
answer to
c?
pink owers.
themselves
to
give
the following
results:
80
of
genetics
to
give
a
b
null
investigation;
test
to
analyse
carried
State
these
results.
c
What
to
out
length
a
with
supports
working.
wing
conclusion
results.
193
chi-squared
student
inheritance
either
bred
expected
69
knowledge
your
have
were
plants
hypothesis for
use
Peru
plants
white-owered
a
of
plants
What
the
breeding
experiment
to
a
the
reason
null
conclusion
whether
hypothesis
can
you
or
not
you
your
analysis
made.
make from
your
answer
b?
investigate
the
Link
in fruit ies.
In
were:
answering Question
12,
look
at
2
Section
long
winged
What
65
conclusions
Explain
your
vestigial
could
answer
you
make
winged
concerning
3.4
21
these
results?
in full.
107
3.8
Patterns
of
Learning outcomes
inheritance
Pedigree diagrams
Questions
On
completion
of
this
section,
be
able
on
genetics
or
family
make
predictions
outcomes

analyse
of
about
genetic
pedigrees
genotypes
and
to
the
Nancy
crosses
describe
patterns
of
Many
predictions
sometimes
Geneticists
set
use
in
the
these
context
when
of
a
pedigree
investigating
explain
them
of
it
often
(1945–)
of
Mary
information
discovered
disease,
these
gives
a
serious
Soto
who
descendants
the
about
a
position
neurological
died
live
in
from
inheritance
the
gene
disorder
,
the
shing
of
the
disease
villages
by
in
pattern.
responsible
studying
the
around
early
Lake
all
for
the
1800s.
Maracaibo
V
enezuela.
inheritance
The
and
Wexler
descendants
determine
make
as
Huntington’s
in

tree.
to:
characteristic

are
you
diagram
should
summary
using
best
way
to
be
sure
that
you
have
learnt
the
genetics
in
this
chapter
is
genetic
to
interpret
of
the
some
data
and
make
genetic
diagrams.
In
the
pedigree
diagrams
diagrams.
genetic

circle
=

shaded
conditions
female;
circle
condition;
S tudy
sure
diagram
or
page
you
set
out
in full. Use
93
the
following
symbols
are
used:
male
=
person
circle
or
with
square
symptoms
=
person
of
a
who
genetic
does
not
show
any
foc us
your
the
Individuals
genetic
of
are
the
condition.
identied
to
help
by
generation
and
number
,
e.g.
I–1
and
III–5.
information
The ABO
on
follow
=
square
unshaded
symptoms
Make
that
square
blood
groups
you.
1
Study
all
1
Figure
the
3.8.1
people
in
carefully
the
and
pedigree
work
out
diagram.
the
Y
ou
genotypes
can
start
of
this
by
2
identifying
those
who
are
AB
and
O.
Their
genotypes
must
female
I
A
be
O
3
2
O
and
I
O
I
.
Now
look
at
the
parents
of
people
who
are
B
4
5
6
O
I
I
1
B
I
I
male
A
and
you
know
that
they
must
have
the
recessive
allele,
O
7
I
,
and
this
be
heterozygous
information
you
if
they
should
are
be
blood
able
to
group
work
A
out
or
B.
With
the
II
O
A
A
1
2
AB
O
3
4
O
genotypes
B
2
Draw
of
all
genetic
children
that
the
people
diagrams
III–3
and
to
in
the
show
III–4
pedigree.
the
might
blood
have
groups
and
of
any
predict
the
III
probabilities
O
Figure 3.8.1
A
B
of
each.
A
The inheritance of ABO blood groups in a
Albinism
family
This
two
pedigree
This
suggests
carefully
the
male
male
with
normal
pigmentation
female
with
normal
pigmentation
3
albino female
you
that
Work
A
as
that
is
the
to
most
the
see
from
it
out
the
different
and
can
condition
suggests
albino
is
phenotypes
both
is
the
of
not
all
because
show
recessive
do
autosomal
for
above
do
males
who
genotypes
symbol
one
condition
that
parents
an
the
people
and
not
the
and
show
the
there
are
just
condition.
if
females
recessive
you
look
have
inherited
condition.
This
condition.
people
dominant
the
allele
in
the
and
a
pedigree,
as
the
using
symbol
I
for
the
recessive
allele.
Y
ou
may
not
know
whether
some
of
2
the
people
dominant
II
the
allele
who
or
do
not
show
heterozygous.
you
do
not
albinism
If
know
this
(see
is
the
are
the
test
homozygous
case
use
cross
on
the
dash
page
for
95).
5
4
Known
in
III
the
which
8
allele.
1
Figure 3.8.2
108
3
The inheritance of albinism
we
carriers
centres
people
A
in
tell
those
genetic
the
the
number
cannot
Identify
of
of
of
pedigree
people
from
who
conditions
unshaded
the
may
for
may
or
indicated
squares.
albinism
carry
pedigree
be
are
circles
the
alone
carriers.
carry
the
recessive
who
by
they
dots
Explain
recessive
allele
are.
but
Module
2
Genetics,
variation
and
natural
selection
Huntington’s disorder
This
that
condition
both
from
a
parent
disorder
inherited
and
who
does
dominant
allele
is
males
not
had
skip
condition;
and
h
is
the
in
females
it.
a
In
a
very
in
the
the
family
generation.
the
allele
normal
different
pedigree
for
used
This
way
have
for
to
albinism.
inherited
this
suggests
Huntington’s,
pedigree
that
H,
it
is
is
the
Notice
the
condition
analysis
an
the
autosomal
Did you know?
dominant
allele.
Nancy Wexler’s
One
complication
with
a
pedigree
analysis
of
Huntington’s
is
that
analysis
develops
late
in
life
as
a
degenerative
disease.
Often
people
pass
on
before
they
know
they
have
it
and
some
people
inherit
located
from
a
parent
who
died
young
without
having
developed
on
pedigree
gene
Huntington’s
disorder
on
the
chromosome
disorder
the
the
for
condition
work
it
4.
Search for
‘Wexler
the
Huntington’s’
to
learn
more.
condition.
5
Work
out
unsure
question
6
State
the
genotypes
possibly
marks
the
for
all
they
unknown
probability
Huntington’s
of
because
that
the
are
people
too
in
the
young,
pedigree.
indicate
If
this
you
by
are
using
alleles.
III–1
and
III–5
have
the
dominant
allele
for
disorder
.
f
m
unaffected
Huntington’s
disorder
S tudy
foc us
I
2
The
genotype
HH
is
never found. All
II
people
with
Huntington’s
are
7
heterozygous.
III
9
Figure 3.8.3
The inheritance of Huntington’s disorder
Haemophilia
Haemophilia
clot
is
males
This
7
very
and
is
none
suggests
Draw
a
an
long.
it
inherited
All
of
is
genetic
those
them
a
diagram
Use
haemophilia.
Draw
III–3
have
H
will
have
from
the
for
a
to
the
in
how
normal
genetic
another
the
recessive
show
the
which
disorder
inherited
sex-linked
haemophilia.
and
disorder
with
the
time
the
pedigree
disorder
taken
from
for
blood
diagram
their
to
are
fathers.
condition.
person
allele
diagram
child
in
to
with
III–6
and
show
h
inherited
for
the
the
allele
probability
haemophilia.
What
is
for
that
III–4
S tudy
Remember
evidence
pedigree
diagram
that
haemophilia
is
a
foc us
the
to
include
the X
and Y
recessive
chromosomes
in
your
answers
to
condition?
Question
8
What
are
the
probabilities
that
a
man
will
transmit
haemophilia
7;
use
superscripts for
the
to
alleles.
i
his
son;
ii
his
daughter;
iii
his
grandson?
male
haemophiliac
male
unaffected
female
unaffected
I
Did you know?
II
Geneticists
research
contribute
projects,
such
to
many
as
the
III
Barbados
National Cancer
investigating family
links
Study,
in
the
1
incidence
Figure 3.8.4
of
breast
cancer.
The inheritance of haemophilia
109
3.9
Practice
exam-style
Patterns
Most
of
these
inheritance
information
an
answer.
symbols
and
do
questions
patterns
in
In
to
order
the
give
you
to
invent
the
draw
have
genetic
alleles
your
information
prose. You
examination,
use for
not
in
you
so
of
to
inheritance
about
interpret
diagrams
will
make
be
to
given
sure
questions:
you
3
the
height
provide
a
Define
the
them
over
own.
terms
the
and
that for
A
test
genes
and
height,
t. The
T,
are
cross
that
the
is
on
of
r. The
made
R,
gene
total
the fruit. The
over
red fruit,
different
was
determine
colour
dominant
allele for
yellow fruit,
two features
gene
have
plants
tall
dwarfness,
a
1
plants
of
allele for
the
use
Tomato
that for
is
dominant
loci for
these
chromosomes.
between
two
tomato
allele
plants.
b
i
When
pure
bred
tomato
plants
with
cut
i
leaves
are
crossed
with
pure
bred
The
possible
plant
plants
with
potato
leaves,
all
the
cut
leaves. Using
D for
the
allele for
and
d for
the
allele for
potato
and
a
genetic
plants
F
have
diagram
cut
to
the
rt. State
of
male
the
gametes
parent
were
of
the
RT,
Rt,
explain
the
genotype
of
this
plant.
State
the
genotype
of
the
plant
chosen
as
the
leaves,
female
draw
as
cut
ii
leaves
chosen
offspring
rT
have
genotypes
tomato
why
all
parent.
Explain
your
answer.
the
iii
leaves.
State
the
phenotypes
that
you
would
expect
1
among
ii
Use
a
genetic
diagram
to
predict
ratio
in
the
if
F
F
2
amongst
A
tomato
breeder
has
a
plants
are
you
not
sure
b
A
cross
plant
with
cut
leaves,
was
used
it
whether
is
it
is
by
would
ratio
expect.
homozygous
made
as
the
between
male
the
parent
in
same
the
plant
test
that
cross
dominant
with
the
genotype
rrTt.
Draw
a
and
genetic
or
to
show
the
genotypes
and
phenotypes
heterozygous.
of
Show,
the
but
diagram
whether
offspring. Give
bred
another
is
cross
1
themselves.
was
c
test
the
that
phenotypic
the
using
genetic
diagrams,
how
you
the
offspring
and
the
expected
phenotypic
could
ratio.
determine
the
genotype
of
a
plant
with
cut
leaves.
4
In
cats,
The
2
In
mice
there
is
a
gene
that
controls fur
short
gene for
hair,
hair
H,
is
dominant
length
over
is
not
is
sex-linked,
long
hair,
sex-linked. An
h.
allele,
colour. There
y
B
are four
alleles
of
this
,
of
another
gene
that
produces
gene:
b
yellow
coat
colour. The
allele
B
produces
black
ch
C
= full
brown
colour
(wild
type);
c
=
chinchilla;
y
coat
colour. The
heterozygous
condition
B
b
B
is
d
c
=
extreme
dilution;
c
=
albino
(white).
tortoiseshell.
The
gene
is
not
sex-linked. The
alleles
show
the
a
following
relationships
to
each
Use
genetic
following
C
is
dominant
to
the
other
three
ch
dominant
to
c
and
c,
but
is
recessive
If
a
to
C
dominant
c
to
c,
but
is
recessive
to
c
and
C
is
recessive
to
the
other
three
the
black
male
cat
mated
with
a
Draw
a
genetic
diagram
to
show
what
would
be
expected
in
the
and
F
cat
homozygous for
when
a
pure
bred
wild
with
a
pure
bred
chinchilla
type
If
the
offspring
freely,
2
mouse
a
genetic
diagram
to
show
short
expect
if
you
crossed
a
produced
in
hair,
the
what
were
are
the
allowed
chances
to
of
interbreed
obtaining
yellow
a
male?
mouse.
what
i
Use
the
inheritance
of
these
two
genes
in
you
cats
would
be
is
b
Draw
will
generation?
long-haired,
crossed
kittens
F
1
generations
of
types
ii
mice
kinds
alleles.
next
b
to
ch
is
what
of
answers
questions.
long-haired,
yellow female
d
a
your
d
is
c
in
alleles
i
c
diagrams
other:
wild
type
mouse
dilution
with
a
to
explain
the
terms
sex linkage
and
codominance
heterozygous for
extreme
chinchilla
heterozygous for
ii
mouse
Explain
why
it
tortoiseshell
c
Is
it
possible for
a
pair
of
mice
to
have
show
all four
phenotypes:
not
wild
male
possible
to
have
a
cat.
offspring
5
that
is
albinism.
In
shorthorn
cattle
there
is
a
gene
that
controls
coat
type,
R
colour. The
chinchilla,
extreme
dilution
and
albino?
diagrams
to
illustrate
your
With
reference
to
your
answers
to
parts
a
to
110
the
term
multiple alleles
a
red
colour,
the
allele
C
white. Cattle
have
a
coat
that
that
is
are
heterozygous for
described
as
roan
–
this
a
light
c,
red
explain
W
gives
answer.
gene
d
C
Draw
gives
genetic
allele
colour. Cattle
with
horns
are
homozygous for
Module
the
allele¸
hornless.
two
a
gene
i
A
p. Cattle
Neither
loci
are
white
that
a
hornless
to
the
these
on
cow
has
with
of
different
with
red
coat
what
loci
and
is
is
allele,
P,
are
7
sex-linked. The
mated
with
a
a
would
genetic
expect
the
student
carried
out
a
and
genetic
natural
selection
investigation
Drosophila melanogaster. Two
characteristics
were
The
observed,
dominant features
wings. The
fruit ies
F
variation
with fruit ies,
normal
the
diagram
in
A
Genetics,
shape. The
bull
homozygous for
Draw
you
is
chromosomes.
horns
condition.
predict
dominant
gene
2
that
results
student
were
were
body
were
carried
colour
grey
out
heterozygous for
and
body
a
test
both
wing
and
cross
gene
on
loci.
as follows:
1
generation.
grey
ii
Cattle
in
the
F
generation
were
black
1
among
body
themselves.
Draw
a
genetic
predict
what
you
would
normal
wing,
83
body
expect
and
normal
wing,
88
diagram
grey
to
and
mated
in
the
body
and
bent
wing,
78
F
black
2
body
and
bent
wing,
74
generation.
The
b
Explain,
using
this
example
of
shorthorn
student
concluded
independent
the
effect
of
dominance
and
that
the
results
showed
that
cattle,
codominance
assortment
had
taken
place.
on
a
Carry
out
a
chi-squared
test
on
the
experimental
phenotypic variation.
data
6
Like
cassava,
means
leaves
that
and
known
as
cell
plants
release
when
is
substrate
up
are
the
and the
cyanide from
damaged. A
down
the
b
of
slowly
enzyme
gene
loci,
at
G/g
in
Use
gene
as
a
chromosomes. The
allele,
use
and
the
enzyme
glucosyltransferase that
linamarin from
a
A
student
the
an
inactive
production of
precursor
enzyme. The
linamarase;
e
allele
during
and
N
of
the
substrates
relationship
G,
and
products
is
E
gene G/g
gene
G
and
as
and
n for
investigated
‘cut’
wings
‘Cut’
shown
g for
the
student
the
in
alleles for
inheritance
the fruit y,
wing
is
carried
wing
body
shape.
of
the feature
Drosophila
controlled
by
a
single
out
two
crosses,
A
and
B,
inactive
Cross
B
enzymes,
below:
parents
females
normal
E/e
males
glucosyltransferase
linamarase
wings
↓
↓
F
linamarin
the
alleles for
below.
↓
→
body
g
↓
precursor
the
alleles for
codes for
an
genes,
summarised
behaviour
explains
codes
substance;
codes for
between
107).
shape.
Cross A
enzyme. The
the
meiosis
assortment
wing
how
page
catalyses the
as
codes for
diagrams,
on
are
gene. The
production of
of
probabilities
symbols
melanogaster.
for the
of
conclusion
result
E/e, which
known
found on different
by
colour
are formed
and
table
student’s
chromosomes
colour
linamarase
reaction.
enzyme
gene
the
independent
8
of two
test
the
Show,
chemical
releasing
happens very
but
(use
cyanogenic. This
hydrogen
broken
temperatures,
speeds
are
they
cyanide. This
walls
The
they
roots
linamarin
hydrogen
normal
clover
to
→
all
with
wings
with
normal
x
‘cut’
males
with
wings
x females
with
wings
all
‘cut’
males
normal
wings
with
‘cut’
1
hydrogen
wings
substance
cyanide
all females
A
pure
breeding
cyanogenic
clover
plant
was
normal
with
a
pure
breeding
non-cyanogenic
with
crossed
plant. All
the
wings
F
1
offspring
were
cyanogenic. When
an
F
generation
F
2
was
produced,
three

cyanogenic

very
phenotypes
females

in
a
wings
356
normal
males
391
normal
376
‘cut’
wings
‘cut’
wings
342
wings
normal
wings
2
cyanogenic
wings
333
‘cut’
wings
non-cyanogenic
the
ratio
Draw
the
of
a
of
9 : 3 : 4.
genetic
parents,
the
F
Explain
the
to
show
genotypes
generations
of
the
and
this
genotypes
a
b
genetic
cross
normal
phenotypes
cross.
Draw
of
of
Use
A. Use
wings
your
diagram
the
and
answer
to
symbol
n for
to
a
the
to
explain
N for
the
the
allele for
explain
how
results
allele for
‘cut’
wings.
these
results
2
why
dihybrid
a
diagram
and
and
F
1
b
normal
339
F
slightly
789
2
were found:
this
ratio
F
cross
of
does
not
show
a
show
typical
ii
9 : 3 : 3 : 1.
is
that
the
sex-linked
allele for
rather
‘cut’
than
wing
being
is:
i
recessive;
carried
on
an
2
c
As
yet
been
non-cyanogenic
produced
by
cassava
selective
plants
have
autosome.
not
breeding. Suggest
c
Give
the
genotypes
of
the
parents,
the
F
and
the
1
why
this
is
so.
F
in
cross
B.
2
111
2
Genetics, variation
4.
1
Principles
of
genetic
Moving
Learning outcomes
Genetic
On
completion
of
this
section,
be
able
not
dene
the
terms
the
genetic
engineering
the
gene
or
removing
(recombinant DNA
technology),
But
restriction enzyme
it
a
can
removal
gene
also
transferring
vector
explain
how
restriction
ligases
the
process
traditional
of
genetic
breeding
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115
4.3
Insulin
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result
sugar
is
only
hormone
glucose
to
controlled
in
increase.
develop
the
that
blood.
Some
diabetes
by
a
of
stimulates
There
people
type
variety
lose
are
the
a
several
ability
to
1.
engineering
insulin
Diabetes

outline
the
advantages
disadvantages
from

of
genetically
explain
why
demand for
using
and
insulin
engineered
there
is
insulin
a
Diabetes
cells
or
the
mellitus
inability
of
is
a
cells
disorder
to
caused
respond
to
by
an
inability
insulin.
There
to
are
produce
two
insulin
types:
increasing

diabetes
type
1
–
insulin-dependent

diabetes
type
2
–
non
worldwide.
insulin-dependent.
T
ype
1
diabetes
secrete
b
insulin
cells
in
the
pancreas,
pancreatic

is
caused
possibly
islets
which
of
by
by
an
the
inability
Langerhans
secrete
this
to
destruction
in
of
the
hormone.
It
is
cell
likely
that
body ’s
starts
length
of
DNA
is
own
cells
are
immune
when
destroyed
system.
someone
is
by
This
quite
the
usually
young.
the
T
ype
gene for
the
2
diabetes
is
an
inability
of
cells
to
insulin
respond
to
insulin
and
may
be
because
there
transcription
are
few
receptors
on
the
cell
surface
membranes
mRNA
of
target
of
diabetes
cells
(see
pages
36
and
73).
This
form
reverse transcriptase
mRNA
plasmid
DNA
–
double-stranded
often
associated
with
obesity
,
a
DNA
high
DNA
is
sugar
diet,
the
inheritance
of
the
alleles
of
polymerase
certain
cut
by
restriction
ethnic
addition
and
groups,
ethnicity
.
particularly
People
people
from
of
some
Caribbean
of
and
‘sticky
genes
enzyme
South
Asian
origin,
are
at
high
risk
of
type
ends’
2
diabetes.
related
plasmids
annealing
with
cut
DNA
to
by
enzymes
be
cloned
to
The
high
global
levels
increase
of
in
obesity
diabetes
is
associated
with
mixed
a
change
from
traditional
diets,
diminishing
between
levels
‘sticky
of
physical
activity
,
population
ageing
and
ends’
ligase forms
sugar–phosphate
‘backbone’
increasing
people
plasmids
treated
taken
with
up
by
calcium
2
diabetes.
ve
also
replicated
with
diabetes
in
Ninety-ve
the
per
Caribbean
cent
have
of
type
bacteria
ions
adult
plasmids
urbanisation.
in
It
is
estimated
population
for
people
has
over
increasing
in
it,
40
that
with
in
the
children
one
levels
in
of
10
Americas.
as
levels
of
of
one
It
the
in
is
obesity
bacterium
increase.
There
bacterium
is
no
is
treated
diabetes
contains
human
gene for
insulin
later
for
diabetes.
insulin
by
extracted
injections
controlled
stages.
treated
bacteria
by
is
although
bacteria
cure
T
ype
1
diabetes
divides
For
insulin.
diet
injections
many
regular
from
of
by
may
years
injections
animals,
and
T
ype
be
required
diabetes
of
such
2
exercise,
was
insulin
as
pigs
and
make
cattle,
which
were
slaughtered
for
the
meat
insulin
Insulin
trade.
This
although
insulin
Figure 4.4.1
most
that
is
of
insulin
diabetics
prepared
modied
bacteria
or
is
now
from
This shows the steps involved in producing GM bacteria cells
that produce insulin on a commercial scale
116
form
yeasts.
still
available
receive
human
genetically
at
Module
The
cut
outline
from
insulin
that
of
genetic
DNA.
In
production
make
reverse
insulin.
replicated
that
was
However
,
proteins
was
DNA
RNA.
was
in
has
the
insulin,
as
yeast
Timeline for
used
the
as
mRNA
that
This
has
inserted
a
states
the
mRNA
the
as
and
a
in
base
molecule.
a
for
to
the
Event
1921
insulin
1955
Fred
1969
Dorothy
US
by
two
right
along
cells
genetically
Sanger
vector
way
and
to
chains
form
other
animal
a
is
and
the
then
and
are
in
b
cells
a
(cDNA)
is
into
the
cells
bacteria
cancer
is
cells,
to
do
insulin
produced
rather
in
than
produce
not
molecule.
eukaryotic
in
bacteria.
by
researchers
determined
Hodgkin
amino
used X-ray
structure
of
in Toronto
acid
in
a
bacterium,
sequence
crystallography
of
to
insulin
determine
the
insulin
synthesised rst
Escherichia coli
(licensed
to
Link
recombinant
the
drugs rm
Reverse
pharmaceutical rm
Advantages of
main
sequence
called
for
Eli
Lilly
starts
selling
recombinant
insulin
as
be
taking
insulin.
using GM
of
this
changed
analogues
immediately
8
and
24
Many
from
viruses
their
RNA
not
form
to
alter
that
after
hours
to
diabetics
shown
into
either
a
insulin
the
both
is
that
properties
act
meal)
give
take
of
the
faster
or
more
of
than
the
same
amino
insulin.
animal
slowly
background
at
the
the
produce
over
blood
time.
These
insulin
is
and
any
less
animal
still
advantage
pure,
insulin
available
than
have
in
the
UK,
insulin
is
a
period
of
the
reliable
leading
of
using
them
animal
and
insulins.
withdrawn
for
increasing
supplies
through
the
health
that
meat
are
it
example.
worldwide.
problems
not
on
However
,
of
main
reported
so
it
dependent
they
are
State
why
The
from
companies
many
The
of
In
the
is
on
factors
that
such
as
they
hypoglycaemic
increasing
the
do
attack
of
not
GM
when
likelihood
human
Describe
in
diabetes
of
of
the
a
blood
diabetic
is
that
warning
there
glucose
of
points
the
people
a
concentration
cells
to
insulin.
are
availability
some
signs
bullet
modifying
is
3
Discuss
the
falls
have
4
advantages
disadvantages
produce
insulin
any
require
insulin.
although
insulin
experience
of
people
Caribbean,
important
people
injections
that
countries,
number
some
more
and
using GM
disadvantage
that
on
68.
Summary questions
genetically
The
page
copy
more
studies
trade.
Disadvantages of
See
of
concentration
produce
one
DNA.
are
process
requiring
enzyme
to
(useful
2
it
an
use
acid
regular
expensive,
is
they
insulin
1
have
that
transcription
advantage
can
insulin
between
transcriptase
Lilly)
Humulin
The
selection
double
bacteria
functioning
proteins,
biotechnology rm Genentech
insulin
1983
natural
enzyme
make
molecule
It
engineering
polypeptide
with
discovered
crystalline
Eli
and
sequence
single-stranded
into
genes
used
pancreatic
substrate
template
that
gene
variation
insulin
Date
1978
isolating
uses
112–113
difcult
double-stranded
made
insulin
why
such
of
a
that
initially
This
cells,
by
pages
very
Genetics,
insulin.
modify
is
of
on
be
mRNA
which
that
give
molecule
produce
Insulin
it.
The
to
to
can
found
molecule
complementary
stranded
that
was
transcriptase ,
single-stranded
then
engineering
fact
2
of
modied
using
cells
to
insulin.
Explain
the
reverse
transcriptase
use
of
the
enzyme
in
genetic
engineering.
coma.
117
4.4
Genetically
modified
Genetically
modied
organisms
organisms
(GMOs)
are
transgenic
organisms.
They
Learning outcomes
have
of
On
completion
of
this
section,
one
DNA
or
more
are
foreign
inserted
genes
alongside
which
the
are
gene
expressed.
so
that
it
is
Promoter
expressed
sequences
in
the
host
you
organism.
should

be
able
dene
the
to:
term
genetically
modified organism

state
at
GMOs
least
in
two
GMOs
(GMO)
examples
medicine
and
Humans
of
GM
in
for
describe
GMOs
the
into
hazards
the
in
environment
precautions
that
explain
the
hazards
are
in
or
in
the
are
crop
rst
discuss
the
social,
and
transfer
that
production
of
have
are
individual
been
crop
using
articial
genes
released
selection.
between
into
the
unrelated
environment
plants.
plants
crop
by
plants
to
be
incorporating
developed
pest
and
had
genes
herbicide
to
improve
resistance.
losses
to
insect
pests
such
as
the
cotton
boll
Pest
weevil;
resistance
herbicide
taken
moral
implications
the
GMOs
by
the
allows
farmers
to
spray
herbicides
to
kill
weeds
without
killing
and
the
ethical
for
GM
resistance

all
plants
using
laboratory
that
allows
crop
taken
reduces
precautions
improved
and
cultivation
GMOs
always
Almost
testing
The

have
releasing
GM
the
agriculture
technology
species.
agriculture

in
crop.
of GMOs.
Most
recently,
crops
have
been
engineered
to
improve
human
health.
An
TM
S tudy
Weeds
our
are
money
plants
herbicides
soil.
spent
to
that
space,
the
are
is
that
act
will
a
GM
as
a
rice
known
vaccine
for
as
Golden
hepatitis
. Another
rice
is
a
GM
banana
B.
foc us
crops for
ions from
example
compete
light,
Huge
every
control
water
and
amounts
year
Feature
Example of
crop
Feature that
disease
papaya
resistance
cotton
toxin
has
been
added
with
resistance
to
ring
spot
virus
of
pest
on
resistance
coded for
by
a
gene from
Bacillus thuringiensis
weeds.
such
herbicide
resistance
soya
corn
gene
(maize)
resistance
corn
(maize)
sugar
improved
so
cane
of
resistance
herbicide
weed
spraying
during
genes
control
to
pests
weevil
gives
allowing
kill
to
glyphosate
control
growth
water
by
of
crop
vapour
loss
rice
nutritional
boll
that
effects
cotton
drought
as
to
several
qualities
genes
precursors
of
to
produce
vitamin A
in
endosperm
Irish
potato
increased
starch
content
Did you know?
Transgenic
confer
virus,
crop
papayas
resistance
which
in
the
to
carry
genes
that
Papaya ring spot
devastated Jamaica’s
mid-1990s.
Most
on
leading
crops
in
are
crop
rms,
although
1998.
118
GM
GMOs
eld
grown
plants
is
Monsanto.
trials
on
in
USA,
carried
Few
GM
genetically
Brazil
out
in
crops
and
Argentina.
Puerto
are
modied
Rico
grown
in
papayas
by
Much
one
the
of
research
the
Caribbean,
began
in
Jamaica
in
Module
GM
The
2
Genetics,
variation
and
natural
selection
livestock
rst
animals
recently,
milk,
GM
may
animals
eggs
bodies
animals
enter
for
or
were
the
have
blood.
been
No
production
developed
food
market
improve
the
transformed
animals
and
to
and
have
Feature
to
been
consumption
by
their
human
produce
given
growth
food
specic
approval
humans
(as
rate;
chain.
of
Example of
these
More
substances
by
in
regulatory
2011).
Feature that
has
been
added
animal
increase
in
growth
rate
salmon
gene from
ability
decrease
in
pollution
through
pigs
(‘enviropigs’)
to
enzyme
the sh
grow
phytase
phosphorus
reduction
prevent
in
dietary
of
human
of
disease
proteins
in
chickens
catch
dairy
genes for
cattle
milk
GM
species
year
to
ocean
pout
that
gives
salmon
round
digest
supplements
phytins
and
so
decreasing
reducing
need for
phosphate
pollution
supplements
transmission
production
all
but
human
do
not
human
transmit
bird
lysozyme
’u
and
other
proteins found
in
milk
microorganisms
Microorganisms
there
are
now
conditions
in
were
many
the
rst
organisms
producing
laboratories
or
a
wide
factories,
Feature
to
range
not
be
of
in
genetically
chemicals
the
wider
engineered
often
in
and
controlled
environment.
Example of
Feature that
has
been
added
microorganism
production
of
animal
protein
bacteria
chymosin
(rennin) for
somatotrophin for
cheese
injecting
making
into
cattle
to
improve
milk
production
wine
production
yeast
improving
to
avoid
the
the
taste
and
production
colour
of
stability
undesirable
of
wine
as
well
as
compounds
(histamines)
production
medical
dietary
of
human
proteins for
yeast
insulin,
supplements
bacteria
tryptophan
Genetically-modied organisms
GMOs
other
are
used
ways.
medical
human
growth
hormone,
vaccines
use
to
This
produce
is
a
list
medicines
of
some
of
that
the
in
are
many
(an
amino
acid)
medicine
difcult
products
to
produce
for
in
treatment
and
research:

insulin
production

human
growth

thyroid
stimulating

factor

vaccines,

many
VIII
–
a
e.g.
(see
page
116)
hormone
blood
for
chemicals
hormone
clotting
protein
inuenza
for
research
including
monoclonal
antibodies
119
Module
2
Genetics,
variation
and
natural
selection
®

Did you know?
human
antithrombin
transgenic
In
a
year
each GM
goat
much
antithrombin
as
collected from
human
90 000
alpha-antitrypsin
transgenic
(See Question
4
advantage
and

Did you know?
Antithrombin
enzyme
inhibits
that
of
using
cheaper
of
in
the
(A
TT)
these
prices
of
precautions
factories
transgenic
thrombin,
promotes
clotting. Antitrypsin
them
blood
inhibits
the
in
milk
by
to
treat
emphysema
produced
in
milk
organisms
the
is
substances
the
large
production
and
concerned.
to
trypsin,
phagocytes
in
which
the
is
lungs
on
are
used
inherited
to
to
doors,
they
are
do
not
requires
these
microorganisms
into
the
compete
engineered
this
produce
GM
release
to
well
produce
energy
in
laboratories
environment
that
in
the
are:
natural
substances
that
not
available
is
readily
give
in
substances
facilities,
prevent
such
escape
of
as
lters
on
air
conditioning
and
air
locks
organisms
during
lethal
genes
are
added
to
the
microorganisms
so
that
they
die
if
recombinant
removed
drugs
as
advantage;
‘wild’
contain
their
microorganisms
containment
released

infections. These
no
to
prevent
the

protease
have
produced
sheep.
environment
by
loss
122.)
Some
an
blood
on
therefore
page
treat
blood
The
donations.
to
can
by
be
)
goats
produces

as
(A
T
ryn
treat
people
deciencies
of
from
the
conditions
of
the
culture.
who
TM
these
Golden
Rice
anti-enzymes.
The
The
S tudy
Many
their
250
ve
worldwide
enough
diet.
It
million
is
of
have
gives
you
of
Vitamin
required
that
some
more
information
about
the
genetic
rice.
A
to
age

A
failure
of
in
is
in
the
diet
for
result
in:
the
health
of
epithelia
and
the
retina
eye.
Vitamin
in
140
the
the
low
deciency
of
rod
light
may
cells
in
the
intensity
retina
(night
to
make
the
pigment
necessary
to
see
blindness)
deciency.
half
severe
in
not
that
under
vitamin A
such
do
vitamin
estimated
estimate
children
this
children
suffer from
Experts
following
modication
foc us
children
receive
problem: Vitamin A deficiency
a

dry,
ulcerated

poor
cornea
that
becomes
cloudy,
leading
to
blindness
million
repair
of
epithelia
leading
to
increased
risk
of
infection,
especially
deciency
measles
that
they
have
become
blind.
In
the
Caribbean,
children
in
Haiti
are
at
highest
risk
of
vitamin
A
deciency.
Solutions

provide
vitamin
providing
measles

these
has
encourage
been
add
vitamin
these
are
S tudy
reach
foc us
children
Read
more
online,
but
websites
side
and
of
about GM
take
you
the GM
treat
their
accordingly.
note
should
technology
that
if
check
debate
they
evidence
you
read
which
advocate
and
opinions
as
rice
We
grain
that
of
exist
able
that
to
is
a
of
very
and
many
and
as
poor
diet
meat
the
eat.
although
transcribed
every
four
to
vaccinations
provide
breast
cooking
as
six
for
months;
polio
and
them
with
vitamin
A
milk
oil,
our
,
world.
enough
poorest
and
aid
milk
and
sugar;
and
who
is
at
supplementary
effective
regular
often
live
mainly
of
a
if
intervals.
beyond
Many
staple
of
the
these
food,
such
vegetables.
yellow
Plants
have
This
organisations.
consisting
pigment,
including
the
UNICEF
,
the
early
the
or
other
and
of
A
voluntary
from
and
of
such
parts
reach
plants,
people
giving
foods.
vitamin
not
little
b-carotene
not
such
many
metabolise
in
feed
content
organisations,
do
example
as
successful
foods,
in
for
time
breast
fortied
doses
on
most
grains
are
to
services,
maize
make
the
to
foods
health
b-carotene
they
120
receive
or
are
A
and
fortied
of
very
same
increase
programmes
children
Many
to
called
Governments
feeding
supplements,
the
mothers
supplements

A
at
have
rice,
genes
substances.
genes
that
translated.
b-carotene,
but
not
that
for
into
the
code
White
code
in
for
rice
these
is
vitamin
part
the
the
are
in
of
the
A.
rice
enzymes
endosperm
the
cells,
Module
Substances
the
in
Enzyme
Genes
pathway
into
inserted
Source of
2
Genetics,
variation
S tudy
genes
and
foc us
A. tumefaciens
plants
to
1
psy
B
the
system
to
C
crt1
bacterium
not
Erwinia
is
a
engineers
get
the
as
a
delivery
plasmid
researchers
into
used
plant
rice
because
infect
adult
the
bacterium
cereal
plants,
does
such
as
rice.
uredovora
←
2
D
enzyme
3
naturally
←
↓
infect
which
2
embryos
↓
plasmid
gall
disease. Genetic
bacterium
cells. The
←
its
crown
maize
use
↓
and
cause
cancerous
←
selection
endosperm
precursor
↓
natural
is
expressed
in
the
3
endosperm
b-carotene
The
solution
genes
taken
to
this
from
problem
maize
and
was
a
to
genetically
bacterium.
modify
Researchers
rice
in
plants
the
using
Golden
TM
project
Rice
the
embryos
used
of
the
rice
bacterium,
plants.
This
Agrobacterium
bacterium
has
a
tumefaciens ,
tumour
to
inducing
infect
)
(T
i
plasmid
that
moves
from
the
bacterium
to
the
host
cells
and
becomes
TM
Figure 4.4.1
incorporated
into
the
rice
chromosomes.
Genes
coding
for
the
Some Golden Rice
in front
enzymes
of some DNA profiles. b-carotene is a
to
make
grew
b-carotenes
into
plants
inherited
varieties
by
of
future
rice
were
which
by
inserted
were
generations.
cross
into
these
self-pollinated
They
can
plasmids.
so
be
the
new
The
embryos
genes
incorporated
yellow pigment, hence the name ‘Golden
were
into
Rice’.
different
breeding.
S tudy
Field
trials
have
been
carried
out
in
the
USA
and
the
Philippines.
It
foc us
is
TM
possible
that
Golden
will
Rice
become
available
to
farmers
in
the
next
You
few
years.
At
the
time
of
writing
(2011)
it
is
not.
The
project
has
should
read
technology
with
much
resistance;
opponents
maintain
that
it
is
better
to
widen
of
those
at
risk
of
vitamin
A
deciency,
for
example
by
of
leafy
raised
by
with
and
ethical
release

of
many
GM
Antibiotic
be
the
example
and
objections
organisms.
resistance
transferred
to
discussions
your
own
will
and
opinions
help
of
this
issues of GMOs
technology
are
this
vegetables.
you form
There
about GM
discuss
your friends, family
teachers. The
Moral
then
increasing
others
intake
and
the
issues
diet
more
met
that
people
Some
genes
of
these
used
pathogenic
make
to
to
the
development,
use
and
support
and
provide
evidence
to
them.
are:
identify
organisms
GMOs
making
could
some
‘escape’
and
Summary questions
antibiotics
redundant.
1

Herbicide
resistance
genes
could
be
transferred
in
pollen
to
Find
GM
species
and
lead
to
the
development
of
‘superweeds’
that
out
about:
i
are
soya
of
and GM
maize;
ii GM
Present
your
herbicides.
ndings

uses
resistant
microorganisms.
to
the
weed
Foreign
genes
could
be
transferred
to
wild
relatives
of
our
crop
as
a
poster
or
a
group
plants
presentation.
so
changing
prove
their
useful
genomes;
sources
of
this
genes
for
may
‘pollute’
crop
those
improvement
species
in
the
that
may
2
future.
Read
objections
modied food.

Foreign
genes
certication
can
that
‘pollute’
they
non- GM
provide
and
‘GM-free’
organic
crops,
which
GMO
crops
outlining
food.
require
more
herbicide
applications
and
just
as
the
in
farmers

or
Farmers
crops
and
do
not
as
non- GM
reduction
cannot
not
keep
‘breed
many
crops
in
there
chemicals
seed
true’;
farmers
so
in
for
this
is
no
used
sowing
in
for
favours
developing
advantage
in
terms
of
cost
following
large-scale
3
crop
poster
benets
of
agriculture
the
and
use
the
as
commercial
to
their
use.
to
agriculture.
the
a
much
objections
pesticide
genetically
require
of GMOs

to
Make
GM
farmers
Explain
GMOs
the
in
advantages
the
of
production
using
of
medicines.
countries.
121
4.5
Practice
exam-style
Aspects
Find
below
genetic
from
a
selection
of
short
engineering. Some
earlier
of
answer
questions
genetic
questions
require
on
questions:
engineering
3
information
The first
genetic
chapters.
human
a
1
a
Explain
how
the following
enzymes
are
used
engineering:
restriction
enzymes,
insulin
Name
the
and
Explain
what
is
meant
explain
how
genetic
modification
by
the
term
vector
the
different vectors
roles
of
which
a
a
by
gene for
plasmid.
would
DNA
and
ii
insert
be
the
used
to
DNA for
i
cut
human
into
the
cut
plasmid.
of
are
used
in
of
20
in
51
amino
amino
acids
acids
that
in
insulin,
are
made
coded for
up
by
of
16
of
DNA.
the
b
bacteria.
bacteria
are
and
What
of
Outline
DNA
insulin
reverse
the
c
the
human
inserting
ligase.
There
b
into
produce
involved
enzyme
plasmid
insulin
transcriptase
to
in
the
genetic
technique
engineering
is
the
tRNA
minimum
molecules
number
of
different
necessary for
the
types
synthesis
of
genetic
insulin?
Explain
your
answer.
engineering.
c
2
The
DNA
target
restriction
sites
enzymes
(restriction
are
shown
sites) for
Explain
why
is
to
likely
indicate
where
the
number
be fewer
you
than
the
have
given
actual
in
b
number
of
below. The vertical
different
lines
the
three
enzymes
cut
types
of
tRNA
required.
DNA.
d
A
triplet
insulin
Hindlll
in
mutation
4
The
the
is TAG.
diagram
in
template
Explain
the first
shows
strand
the
of
likely
base from T
how
the
the
gene for
effects
of
a
to A.
gene for
human
EcoRI
antithrombin
cells
from
Haelll
a
i
Describe
the features
of
the
restriction
was
introduced
into
extracted
goats.
nuclei
goat fetus
from
removed
goat
sites
human
gene for
enucleated
shown
in
the
diagram.
cells
With
reference
diagram,
to
explain
restriction
the
the
enzymes
information
advantages
in
genetic
in
of
added
the
identical
separately
DNA
has
lengths
with
each
of
of
the following
DNA
the
were
of
cells
using
removed
from
treated
restriction
sequence
to
nucleus
cells
each
added
enucleated
base
AGT TGAAAGGCC T T CA T CGCACCC T T AA T T CGTGGCCAAGC T T
T CAAC T T T CCGGAAGT AGCGTGGGAA T T AAGCACCGGT T CGAA
b
i
State
how
divide
many fragments
after
treatment
of
with
DNA
EACH
will
of
by
embryos
5’
be
implanted
ii
Explain
further
mothers
enzymes.
why
some
treatment
of
the fragments
before
they
can
need
be
inserted
kids
into
into
the
surrogate
restriction
mitosis
3’
embryos
present
cell
pairs.
to form
3’
to
enzymes. The
cells
5’
nuclei)
engineering.
nuclei
Three
(cells
antithrombin
without
ii
oocytes
grow
into
goats
plasmid vectors.
that
Retroviruses
have
RNA
as
their
genetic
secrete
human
antithrombin
material.
in
their
milk
c
RNA
of
can
be
incorporated
retroviruses for
eukaryotic
used
to
cells.
insert
transformed
Explain
genes
cells.
into
insertion
how
into
the
into
the
genome
bacteria
this
or
technique
genome
of
is
these
a
Explain
b
Complex
cannot
what
produce
Explain
by
proteins
produced
by
why
complex
antithrombin.
122
meant
human
be
bacteria.
is
a
transgenic
such
as
antithrombin
genetically
bacteria
human
are
proteins
animal.
modified
unable
such
to
as
Module
Animal
make
growth
c
cells
in
human
i
culture
have
also
proteins,
such
as
modified
and
to
6
Several
human
to
hormone.
Discuss
advantages
modifying
animals,
cells,
as Chinese
such
Outline
human
the
such
to
as
goats,
and
ovary
animal
cells,
in
human
using
a
State
b
Explain,
what
is
meant
by
the
term
soya,
are
Explain
these
genetic
proteins.
b
variation
have
all
the
a
natural
selection
genetically
toxic
engineered
compound
Bacillus thuringiensis (Bt). GM
in
rape,
cotton,
countries
maize
such
as
and
the United
Brazil.
advantages
of
growing
Bt varieties
of
plants.
how
are
on
seed
grown
and
crop
Outline
oil
and
been
based
bacterium,
of
above,
5
plants
poisons
States, China
to
a
hazards
the
tobacco
proteins.
produce
crop
varieties
genetically
hamster
potential
engineering
of
Genetics,
express
from
the
produce
ii
been
insulin
2
crop
plants,
genetically
such
as
modified
those
to
listed
improve
gene therapy
productivity.
in
outline,
how
gene
therapy
is
carried
c
Outline
the
potential
risks
of
growing GM
crop
out.
varieties
c
Outline
the
advantages
and
hazards
of
and
suggest
steps
that
can
be
taken
to
gene
minimise
them.
therapy.
d
7
What
Mexico
of
that
maize;
the
banned
samples
DNA
are
the
maize
is
the
limits
of
cultivation
grown
only found
sequence
Cuzco valley
in
gene
Peru
in
therapy?
of GM
remote
in GM
in
mountain
maize. The
originates from
and
maize
In
regions
researchers
a virus
30-year-old
1998.
that
maize
an
investigation
of Oaxaca
tested for
infects
cobs from
in
a
carried
southern
promoter
cauliflowers. They
museum
in
2000
Mexico for
sequence
also
collections
out
in
tested
a
researchers
specific
that
Mexico. The
sequence
genetic
blue
of
engineers
maize from
table
tested
shows
the
use
in
remote
their
results.
Sample of
maize
Presence
() or
absence
() of
local
variety
of
maize
1

(1–3%
of
grains
sampled)
local
variety
of
maize
2

(1–3%
of
grains
sampled)
maize from USA

(100%
of
grains
sampled)

(100%
of
grains
sampled)
GM
Bt
GM
herbicide
blue
resistant
maize from
maize from
maize from USA
promoter
sequence
in
maize
genome

Peru
30-year-old

museum
collection
a
Explain
why
the
researchers
used
i
blue
maize
and
30
year
old
maize,
and
ii GM
maize from
the USA
in
their
study.
b
Suggest
Mexico
This
research
sequences
that
In
c
d
reasons for
two
the
2009,
in
was
the
Discuss
had
highly
the
is
presence
the
ban
the
third
germ
government
meant
reasons
of
by
the
the
on GM
controversial
maize. A
entered
Mexican
what
the
after
Mexican
DNA
Explain
years
promoter
sequence
in
the
and
repeat
investigation
investigations
in
in
2008 found
2003–04
some,
some
GM
ii
countries
permitted
term
do
trial
plantings
of GM
grains from
southern
but
did
did
not find
not
any
confirm
of
the
these
DNA
original
conclusion
maize.
why:
permit
the
planting
permit
the
planting
foc us
of
Promoter
not
maize
germ line
crops
others
of
line.
S tudy
i
genome
maize.
of GM
crops.
sequences
polymerase
‘upstream’
of
engineering
be
and
each
must
transcribed
are
attachment
sites for
transcription factors. The
in
gene. Any
have
the
a
gene
promoter
host
RNA
sequences
inserted
by
sequence
are
genetic
to
allow
it
to
cell.
123
3
Genetics, variation
5.
1
Variation
Learning outcomes
completion
of
this
natural
selection
(1)
Types of variation
V
ariation
On
and
section,
refers
to
differences
between
the
genotypes
and
phenotypes
of
you
organisms.
should
be
able
to:
Phenotypic

dene
the
term
organisms

explain
the
difference
and
and
in
is
their
obvious
to
us
behaviour
.
It
in
is
the
also
physical
evident
appearance
in
aspects
of
of
biology
between
that
interspecic
variation
variation
we
cannot
see
so
easily,
such
as
biochemistry
and
in
haemoglobin
(see
physiology.
intraspecic
Examples
of
this
are
the
variation
page
130)
and
variation
blood

describe
the
continuous
difference
and
between
discontinuous
group
reection
colour
of
antigens
of
(see
genotypic
the
4
page
102).
variation
o’clock
plant
as
(see
Some
it
is
page
phenotypic
with
the
variation
codominance
is
in
a
direct
ower
96).
variation
We

list
examples
of
can
identify
phenotypic
variation
at
two
levels:
discontinuous

interspecific
variation

intraspecific
variation
variation

select
and
present
draw
data
on
bar
charts
to
discontinuous
variation.
Interspecic
to
these
differences
when
In
this
do
your
differences
between
between
classifying
different
organisms
and
different
species;
when
species.
We
biologists
using
keys
use
use
to
section
you
will
need
to
know
about
intraspecic
variation.
foc us
course
some eld
identication
eld
the
distinguish
species.
Intraspecic
During
is
differences
identify
S tudy
variation
these
work
key
you
will
probably
and
use
an
in
the form
of
between
variation
individuals.

discontinuous

continuous
is
variation
There
are
within
two
a
types
species.
of
It
is
the
intraspecic
difference
variation:
variation
a
variation
guide.
Discontinuous
variation
non- overlapping
is
the
categories.
type
Y
ou
of
can
variation
see
in
examples
which
of
this
there
type
are
of
clear
,
variation
Link
in
humans
attached
Read
page
90 for
the
phenotype
the
list
lobes.
on
page
There
are
90.
two
People
either
distinct
have
attached
categories
with
no
or
non-
intermediate
differences
forms.
between
in
ear
and
Other
features
in
the
list,
such
as
height
and
hand
span,
show
genotype.
continuous
variation
as
there
is
a
range
of
sizes
between
two
extremes.
Discontinuous variation
This
refers
categories.
to
intermediate
variation
–
This
For
S tudy
population
will
be
in
this
area
at
the
section.
It
is
all
it.
of
sizes;
ABO
have
blood
system
intermediates
variation
the
is
ability
groups
there
taste
by
a
are
wings
in
are
between
caused
to
that
long
in
or
clear
short
humans
four
contrasting
wings,
show
categories
there
are
no
discontinuous
–
A,
B,
AB
and
O
them.
genes;
bitter
the
environment
chemical,
PTC,
is
has
no
effect.
determined
of
one
same
species
time.
in
to
taste
on
chromosome
PTC;
people
7.
who
The
are
dominant
allele
homozygous
gives
by
recessive
people
The
types
of
food
we
eat
may
modify
how
we
taste
cannot
PTC,
but
the
the
make
non-tasters
into
tasters.
same
Data
on
because
124
the
(T
AS2R38)
ability
cannot
organisms
in
any
differences
either
used
taste
often
wing
example,
gene
the
term
type
ies
foc us
a
The
–
without
qualitative
Fruit
discontinuous
each
category
variation
is
a
is
separate
presented
group.
in
the
form
of
bar
charts
Module
2
Genetics,
60
variation
and
natural
selection
Did you know?
53%
The
percentages
of ABO
blood
noitalupop
50
groups
in
different
populations
vary
human
signicantly.
South
40
American
Indians
are
all
blood
group
35%
eht
O; Australian Aborigines
groups O
fo
30
egatnecrep
you
for
and A. What
about
the
the ABO
alleles
blood
are
does
of
in
blood
this
the
group
all
tell
gene
these
20
populations?
10
8%
4%
0
A
B
AB
blood
Figure 5.1.1
O
groups
Bar chart to show percentages of the population of Portugal with different
ABO blood groups
Rules
for

use

draw

bar
drawing
most
of
the
the
chart
charts
width;
bar
can
there
charts:
grid
in
be
provided,
do
not
make
the
chart
too
small
pencil
made
must
be
of
lines,
space
or
more
between
the
usually,
lines
or
blocks
bars;
of
they
equal
do
not
touch

the
intervals

the
y-axis
between
the
blocks
on
the
x-axis
should
be
equidistant
Did you know?
scale
should
should
be
properly
usually
start
at
scaled
zero
with
and
equidistant
this
should
be
intervals;
written
at
the
the
The
base
of
the
axis;
if
all
the
numbers
are
large
a
displaced
origin
may
blood
know
used
but
the
start
number
should
be
clear
at
the
base
of
the
the
y-axis
the
table
of
should
results
be
the
lines
or
blocks
labelled
with
the
headings
and
units
taken
Rhesus
U
should
be
arranged
in
the
same
order
as
results
or
in
a
logical
sequence
from
left
to
right
that
most
the ABO
in
a
(increasing
system.
more
people
system
But
there
and
are
negative
including
which
the
occurs
very
in
rare
people
table
without
of
are
from
many

about
y-axis
the

groups
be
the U
antigen. U
negative
or
red
blood
cells
are found
in
people
of
decreasing)
African

each
block
should
be
identied
descent.
clearly.
Summary questions
1
Dene
the
term
4
variation
Describe
of
2
Distinguish
and
intraspecic
continuous
3
The
A
between
41%,
B
Plot
b
Brazil
variation;
of
these
5
and
9%, AB
was
3%, O
a
as
bar
in
Brazil
is:
why
colony
are
6
Explain
taste
until
there.
1822
Suggest
different from
in
variation
a
the
blood
and
proportion
blood
the
presenting
chart.
migrated
percentages
groups
47%.
a
Portuguese
Portuguese
State
different
blood
variation
groups
is
an
discontinuous
example
variation.
interspecic
discontinuous
different
these gures
many
pairs:
variation.
proportion
a
the following
why
intraspecic
groups
steps
the
bitter
you
is
of
would
variation
chemical
a
population
plotted
in
take
the
called
as
in
a
bar
with
chart.
determining
ability
of
people
and
to
PTC.
and
why
those
in
Portugal.
125
5.2
Variation
(2)
Learning outcomes
Continuous variation
This
On
completion
should
be

examples
list
able
of
this
section,
select
and
of
draw
data
histograms
on
describe
differences
within
a
species.
Organism
Examples of
humans
height,
environment
body
mass,
hand
span,
to
beef
some
continuous variation
cattle,
goats
milk
yield,
e.g.
volume
of
milk
per
week
continuous
variation

quantitative
continuous
dairy
present
to
to:
variation

refers
you
effects
on
the
of
cattle,
pigs,
sheep,
goats
body
mass,
carcass
sheep
wool
thickness
soya
width
weight
the
phenotype.
of
leaves,
mass
of
pods,
total
yield
of
beans
S tudy
The
type
of
foc us
banana
variation
shown
in
below
distribution
as
is
the
called
three
a
normal
measures
‘average’
(mean,
median
of
are
all
about
the
leaves,
yield
of fruit
two
examples
extremes
has
–
no
clear
shortest
categories;
and
tallest,
instead,
lightest
there
and
is
a
range
heaviest,
etc.
of
describe
continuous
variation
you
need
to
measure
and
then
collate
the
and
data.
mode)
these
between
T
o
the
of
the
Each
histogram
length
The
results
are
usually
collected
in
a
tally
table
before
being
same.
presented
the
as
range
lengths
a
into
of
50
histogram.
classes.
leaves
In
For
with
collating
example,
a
total
the
if
results
you
range
of
were
8
to
it
is
necessary
collecting
38 mm,
to
divide
information
you
could
divide
on
the
25
range
into
nine
classes.
This
is
shown
in
the
tally
table
and
histogram.
20
sevael
Leaf
length/mm
Tally
Number
Percentage
15
frequency
fo
rebmun
10
8–11
//
2
3
12–15
////
4
6
5
7
8
11
25
35
13
18
7
10
5
0
34–04
93–63
53–23
13–82
of
72–42
Figure 5.2.1
32–02
91–61
51–21
11–8
length
///
leaves/mm
Histogram to show the
variation in leaves recorded in the tally
///
table
//
////
4
6
40–43
///
3
4
Total
71
71
100
Continuous
variation
Many
inuence
the
genes
genes
involved
the
feature.
inuence
the
feature
genes,
each
is
determined
the
have
inuence
two
126
36–39
same
multiple
The
in
an
recessive
genes
alleles
separate
additive
allele
by
feature
so
genes
add
is
that
and
fashion.
could
and
which
a
5 mm
the
many
the
In
by
known
alleles
the
polygeny.
alleles
simple
to
environment.
as
at
at
each
each
locus
example
length
of
Often
locus
with
a
leaf
just
and
Module
each
dominant
allele
add
10 mm.
Leaves
would
then
vary
in
length
2
Genetics,
variation
and
features
40 mm
such
as
so
leaf
there
length
would
are
be
ve
different
inuenced
by
classes.
many
more
environmental
effects,
such
as
light,
water
and
than
two
nutrient
the
effect
draw
a
of
line
smoothing
Histograms
scale
are
between
Rules
for

use

draw

the
through
most
of
the
out
the
be
blocks

the
area
the
each

the
variation
This
table
is
the
are
be
do
with
to
give
not
on
the
a
bell-shaped
cur ve
of
use
1,
these for
2,
5
or
scaling
10
axes,
if
not
use
3
or
6.
histogram.
variation
separate
as
a
continuous
categories.
not
make
the
histogram
too
small
an
appropriate
proportional
all
opposite
the
labelled,
but
variable
and
is
continuous;
it
scale
touching
table
4.0
to
is
the
in
size
of
the
similar-sized
class;
the
classes
so
the
same
e.g.
is
‘3.0
not;
to
4.0
3.9’
will
which
be
means
included
that
in
the
3.0
is
next
4.9
the
equidistant
number
intervals;
discontinuous
of
genes
frequency
label
and
with
and
should
appropriate
continuous
be
properly
units.
variation.
Continuous variation
qualitative,
quantitative, e.g. mass
absence
few,
the
or
Discontinuous variation
with
of
are
independent
drawn
or
influencing
bars
graphs,
pencil
clearly
be
phenotype
number
the
continuous
items
the
class,
campares
appearance
in
represents
with
of
provided,
blocks
this
to
y-axis
the
block
in
should
in
4.0
scaled
data
the
blocks
included
class:
grid
should
of
of
present
represents
leaf-length
widths
the
labelled
the
centre
line
multiples
histograms:
histogram
x-axis,
should
to
extremes;
drawing


used
the
with
availability
,
do
we
foc us
genes
or
have
selection
However
,
As
and
natural
between
S tudy
20 mm
and
no
e.g.
of
presence
a feature
and length; a range with
intermediates
often
just
one
many intermediates
gene
many
(polygenic)
Summary questions
(monogenic)
1
feature
Dene
the
term
continuous
variation.
effects
of
different
different
effects
all
have
the
same
2
genes
on
the feature
effect,
usually
Distinguish
following
pairs:
histogram;
effects
of
alleles
at
large
effects
small
effects,
between
the
additive
bar
chart
monogenic
and
and
usually
polygenic.
each
locus
additive
3
effect
of
the
small
or
non-existent
Explain
the
steps
you
would
take
large
in
measuring
and
presenting
environment
variation
in
Poinciana,
presentation
bar
chart
frequency
Suggest
cat
environment on
extreme
honey
bee
case
of
the
colonies.
effect
Most
of
the
female
environment
honey
bees
on
phenotype
develop
into
occurs
worker
they
are
fed
on
a
diet
of
pollen
has
how
to
become
princesses
and
and
then
nectar
.
Y
oung
female
her
page
in
effects
occurred
genes
in
to
of
the
an
the
environment
organism
organism’s
during
are
its
not
queens
are
inheritable
lifetime
reproductive
Siamese
markings,
kittens
73 for
fed
royal
are
not
as
have
but
them.
none
See
ideas.
Discuss
the
effects
of
the
bees
on
the
phenotype
jelly.
of
The
a female
black
environment
destined
Royal
bees
5
because
of
phenotype
of
An
length
histogram
4
Effect of the
pod
Delonix regia.
changes
that
transmitted
to
have
the
individual
explain
why
organisms
these
and
effects
are
not
inheritable.
organs.
127
5.3
Mutation
The
Learning outcomes
term
biology
On
completion
should
be
able
of
this
section,
is
you
mutation
to
passed
refer
to
all
to
explain
the
describe
term
Mutations
mutation
gene
mutation
and
discuss
chromosome
give
an
of
S tudy
in
foc us

A
change
that
cell
suppressor
disrupt
rise
they
mutation
then
the
divide
by
more
occurs
cells
in
a
germ
line
derived from
occurs
by
in
and
a
it
is
single
replication
and
used
cell
in
and
mitosis.
to
this
cancers.
genes
control
control
mitosis.
so
that
cells
divide
Mutations
that
only
affect
the
occur
cells
carry
the
as
and
somatic
are
not
passed
on
to
the
next
mutations
important
for
may
nucleus
meiosis.
50%
of
produced
mutant
by
occur
these
or
this
the
and
chapter
that
can
affect
mutations
can
either
structure
be
are
ger m
passed
whole
occur
line
of
to
mutations
the
next
chromosomes
when
change
on
that
occur
the
a
nucleus
number
individual
of
or
generation.
single
divides
genes.
by
mitosis
chromosomes
in
or
a
chromosomes.
Gene
mutations
occur
during
DNA
replication
during
interphase
of
the
the
cycle;
these
are
changes
to
the
number
or
sequence
of
base
pairs.
meiosis
allele.
Chromosome
These
may
mutation
involve:

primary
cells
it
cell
haploid
known
Chromosome

will
tumour
genes
giving
which
are
meiosis;
will
and
these
gamete-forming
Changes
a
of
change
example.
in
cell,
DNA.
descendants
meaning
mutation
Even
and
If
word
example
generation

in
a
give
organism
an
from
to:
uncontrollably

changes
the
Proto - oncogenes

derives
polyploidy
–
increasing
the
number
of
sets
of
oocyte
chromosomes
homologous
pair
of

chromosomes
metaphase
meiosis
of
21
aneuploidy
–
increasing
individual
I
changes
in
the
translocation
and
homologous
pair
not
during
separate
anaphase
1st
polar
with
chromosome
it
chromatids
chromosomes
of
both
separate
II
in
syndrome
meiosis
polar
with
two
such
is
as
a
detached
an
example
a
child
of
aneuploidy.
has
an
extra
In
most
chromosome
because
in
homologous
anaphase
I
of
chromosomes
meiosis.
do
This
most
often
take
over
through
40
of
in
years
anaphase
the
production
sperm.
to
I
The
proceed
(see
page
of
reason
from
83)
is
eggs
early
to
rather
that
cells
meiosis
form
eggs.
than
in
may
and
go
The
II
of
of
Down’s
older
syndrome
The
women.
is
higher
chances
among
rise
the
steeply
after
body
the
two
chromosomes
21
is
properly
production
children
2nd
with
chromosome
another
.
because
happens
separate
incidence
ovum
chromosome,
a
syndrome
happens
This
occurs
normally
a
of
21
21
the
to
of
part
body
the
chromosomes
of
no
not
both
structure
when
reattached
Down’s
21.
oocyte
meiosis
number
I
cases
with
the
does
Down’s
chromosomes
decreasing
chromosomes
I

secondary
or
at
meiosis
age
of
35.
21
Figure
5.3.1
separate
in
existence
shows
how
anaphase
of
three
I
a
pair
and
of
are
chromosomes
inherited
chromosomes
of
the
fails
together
.
same
type
to
The
is
fertilisation
known
normal
sperm
as
because
one
chromosome
of
not
inherited;
meiosis
to
they
arise
form
Females
have
had
children
with
with
Down’s
both
Down’s
with
syndrome
and
without
are
fertile
Down’s.
and
Males
21
This diagram shows how a pair of homologous
chromosomes fails to separate during meiosis I
128
are
during
with
trisomy
Figure 5.3.1
T
risomies
non-disjunction
21
gametes.
zygote
trisomy.
with
syndrome
chromosomes
X
occur
,
chromosome
and
are
but
No.
sterile.
only
21
T
risomies
babies
survive.
with
of
other
trisomies
T
risomies
of
of
other
the
Module
chromosomes
are
5%
Down’s
be
of
cases
of
usually
lethal
before
syndrome
are
or
the
around
result
the
of
time
of
birth.
translocation
2
Genetics,
About
that
variation
Polyploidy
the
total
number
of
chromosomes
have
been
selection
Did you know?
some
in
natural
can
inherited.
Changes
and
important
in
is
uncommon
species
of
lizard
in
are
animals;
an
the
example.
evolution
50%
of
of
plant
owering
associated
with
species,
plant
large
especially
species
size,
so
are
in
those
polyploid.
cultivated
that
are
cultivated.
Polyploidy
varieties
are
is
often
Nearly
often
much
larger
Link
than
the
diploid
wild
relatives
from
which
they
evolved.
Polyploidy
Gene
speciation
mutation
of
Changes
These
to
can
individual
genes
involve
the
sequence
of
nucleotide
how
is
–
this
a form
see
of
page
happened
very
abrupt
139 for
in
details
cord
grass.
bases.
be:
Link

substitution

frameshift
of

one
or
stutter
–
a
are
of
page
109).
the
is
template
effect
strand,
this
is
of
is
the
the
sequence
the
lower
is
one
a
duplicated
of
changes
the
a
it
coding
the
the
that
of
it
system
becomes
bases
upper
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Figure 5.3.2
leu
you
of
mutation.
gly
A
phe
effects
help
–
A
phe
the
to
gly
A
ser
the
of
67
gly
A
val
understand
details
page
strand.
A
ser
on
in
T
tyr
the
strand
A
leu
to
code
(see
T
ser
back
longer
disorder
of
The
Look
to
repeat
nervous
sequence
codes.
addition
genetic
number
in
so
by
bases
Huntington’s
on
which
the
more
protein
cause
for
changes
or
increase
for
another
triplets
of
which
gene
for
A
phe
d
and
of
deletion
The
pair
T
phe
c
sequence
This
acid
base
A
phe
b
one
mutations
the
amino
of
the
pairs.
section
shows
and
the
or
generation.
DNA
a
base
repeated
5.3.2
which
these
each
the
in
change
bases
with
Figure
the
more
sequences
has
–
–
STOP
The effects of gene mutations on an amino acid sequence of a polypeptide
Summary questions
can be: a quite small; b very large; c non-existent; d catastrophic
1
The
chances
of
a
mutation
are
increased
by
exposure
to
mutagens,
Dene
the
terms
mutation
and
which
mutagen.
are
environmental
are
radiation
factors
that
interact
with
DNA
to
change
it.
Examples
2
tobacco
known
DNA
smoke.
as
not
and
Agents
various
that
cause
chemicals
such
mutations
as
that
benzpyrene
cause
cancers
polymerase
that
infallible
is
has
in
and
a
Distinguish
between
gene
in
mutations
are
and
chromosome
mutations.
carcinogens
nucleotide
is
(X-rays)
proof-reading
the
wrong
errors
place.
occur
capacity
so
However
,
during
removes
this
replication.
proof
and
replaces
reading
a
ability
3
Find
21
out
on
the
the
of
effects
he
of
phenotype.
information
the
effects
as
on
a
trisomy
Present
table
the
showing
different
aspects
phenotype.
129
5.4
Sickle
cell
Learning outcomes
anaemia
A
substitution
Sickle
On
completion
of
this
section,
cell
be
able
describe
to
the
sickle
of
state
mutation
cell
the
anaemia

explain
that
leads
severe
on
the
of
sickle
of
The
the
result
b-globin
of
of
a
substitution
haemoglobin.
mutation
This
does
in
the
not
sixth
sound
the
gure
if
but
all
the
shows
coding
as
you
see
b-globin
that
strand
can
the
leads
in
5.4.1
polypeptides
change
to
Figure
the
from
change
A
in
to
from
it
can
like
have
a
haemoglobin
T
in
CTC
the
to
very
are
sixth
template
strand
and
the
position
hence
the
substitution
of
valine
for
CAC
glutamic
in
the
acid
in
individual
global
allele for
change,
cell
distribution
sixth
sickle
cell
of
the
primary
structure
of
b-globin.
This
type
of
of
haemoglobin
the
is
for
consequences
changed.
anaemia
effects
the
gene
important
triplet

the
to:
very

anaemia
you
triplet
should
mutation
anaemia
normal
is
form
known
as
haemoglobin
S
(HbS)
to
distinguish
it
from
the
(HbA).
S
(Hb
)
Molecules

discuss
cell
the
inheritance
of
sickle
anaemia.
The
R
form
groups
of
haemoglobin
with
of
this
R
and
cells
sickling
Link
of
with
ow
.
To
remind
amino
yourself
acids,
see
about
page
R
groups
and
these
These
this
There
can
The
foc us
on
page
of
a
substitution
in
ow
Figure
5.3.2a
also
People
pain
for
are
120
position
they
an
that
is
6
area
gain
on
and
its
of
the
S
beta
lose
surface
hydrophobic.
haemoglobin
polypeptide
are
enter
sickle-shaped
damages
get
the
removed
stuck
people
major
in
with
red
or
oxygen.
that
has
The
globin
molecules
is
to
regions
of
low
attracted
stick
oxygen
crescent-shaped.
cell
from
membrane
the
capillaries
this
organs
feeling
and
that
experiencing
many
and
is
and
circulation
making
condition
reduced
years
before
cells
only
tired
by
they
live
and
cell
it
have
and
by
The
the
sickle
repeated
shortens
the
spleen.
difcult
there
breathing.
enough
crisis
having
sickle
the
loss
can
are
red
for
cell
be
blood
crises
much
destroyed
lethargic
and
in
10
an
and
at
cells
days.
to
live
do
to
to
in
pain.
to
a
or
good
spleen
the
to
the
medical
age.
faster
rate
live
liver;
of
hospital
with
young
cells
the
rest
taken
a
at
blood
spleen
20
inability
be
the
without
die
red
the
to
ow
for
people
but
blood
Normal
between
need
disease
Blood
blood
Some
crises,
cell
of
marrow
.
for
in
not
transfusions.
with
bone
is
sickle
without
caused
in
a
difculty
there
blood
children
is
days
are
fever
much
produced
blood
than
between
90
sickle-shaped
Symptoms
strenuous
of
anaemia
exercise.
129.
this
and
5.4.1
has
gene.
on
shows
the
Notice
organ
b-globin
Sickle
Did you know?
the
In West Africa
anaemia
the
is
incidence
4%
of
all
live
of
sickle
births.
because
cells
They
kill
to
are
the
against
occurs
it
gene
is
gives
a
then
taken
but
malaria
anyway
the
also
has
and,
cascade
homozygous
multiple
the
the
term
on
effects
on
applied
the
to
of
for
effects
the
cells,
that
mutant
tissues,
genes
like
organs
the
phenotype.
malaria
which
little
and
is
effects
disorder
It
is
of
cycle
causes
the
happens
against
causes
and
the
the
benet
red
for
those
people
common
spends
oxygen
within.
medical
to
malaria.
circulation
parasites
without
that
surprisingly
life
parasite
the
who
is
protection
out
DNA
have
multiple
complex
the
decrease,
cells
can
Pleiotropy
mutation.
by
in
someone
against
has
Invasion
change
in
has
anaemia
Plasmodium,
cells.
a
that
substitution
world
red
body
that
gene
cell
the
systems.
Protection
130
to
relief
many
red
Figure
cell
can
be
so
anaemia
they
and
shown
at
causing
mutant
They
cells
increase
facilities
is
leucine
valine
when
exposes
12.
disease
example
and
become
happens,
blood
receive
mutation
the
they
cells.
which
body.
An
shape
of
may
S tudy
of
area,
unsickling
sickle
If
change
attached
precipitate.
concentration
life
group
hydrophobic
together
When
oxygen
phenylalanine
hydrophobic
to
no
cells
and
in
some
areas
The
malarial
part
of
it
in
to
become
killed.
Not
the
intervention,
the
blood
within
the
misshapen.
only
this
disorder
the
of
for
parasite,
red
concentration
Unfortunately,
with
homozygous
does
this
protection
since
condition
sickling
is
lethal.
Module
gene for
β-globin
of
2
Genetics,
variation
and
S
allele
Hb
mutation
template
to
sixth
strand
first
his
seven
leu
amino
thr
pro
acids of
glu
DNA
CACGTGGACTGAGGACACCTC
glu
normal
val
β-globin
first
his
seven
2
α-
and
to
2
β-globins
make
Millions
of
A
A
Hb
have only
red
blood
low
cells
oxygen
Hb
packed
in
areas
valine
replacing
glutamic
red
S
have
of
abnormal β-globin
both types
Hb
β-globin
S
Hb
have
abnormal
only
β-globin
of
concentration
sickle-shaped
increase
to
glu
cells
viscosity
from
acids of
val
of
into
S
Hb
β-globin
pro
assembled
molecules
blood
A
leads
thr
haemoglobin.
haemoglobin
normal
leu
amino
substitution
Hb
Hb
triplet
of
CACGTGGACTGAGGACTCCTC
val
selection
haemoglobin
A
allele
natural
red
blood
circulation
in foetal
cells
by
the
removed
sickle-shaped
liver
jaundice
capillaries
anaemia
heart failure
red
to
pain
of
blood
blood
cause
cells
sickle
increases
get
cell
stuck
in
crisis
fever
kidney
damage
haemoglobin
Figure 5.4.1
Both
the
The effects of a substitution mutation in the b-globin gene. Viscosity means ‘thickness’ and resistance to ow.
normal
allele
and
the
mutant
allele
are
active
in
people
who
are
Summary questions
heterozygous.
blood
They
functions
produce
fairly
both
normally
as
forms
they
of
the
have
polypeptide
haemoglobin
and
their
molecules
with
A
1
two
normal
b-globins
and
some
with
two
mutant
b-globins
and
The
the
with
both
types.
In
a
carrier
,
the
presence
of
the
malarial
gene
Hb
parasite
production
red
blood
cells
to
rupture
prematurely,
so
the
parasite
of
controls
the
b-globin
causes
polypeptide
the
S
/Hb
some
of
haemoglobin.
cannot
S
People
reproduce.
Furthermore,
the
polymerisation
of
haemoglobin
affects
who
are
homozygous,
Hb
the
S
Hb
ability
of
malaria,
forms
of
the
parasite
people’s
the
to
digest
chances
b-globin
in
of
haemoglobin.
survival
their
Therefore,
actually
haemoglobin.
increase
This
mild
if
in
areas
they
form
have
is
,
Draw
a
a
cell
result
trait
of
and
natural
is
common
selection
in
(see
places
page
such
as
West
and
known
East
inherit
sickle
cell
who
are
heterozygous
they
are
like
beta
of
the
anaemia
and
Some
thalassaemia
forms
cell
this.
are
anaemia
carry
other
thalassaemias
and
the
do
genetic
also
Africa
show
how
in
infectious
areas
disease.
of
serious
the
parents
mutant
report
of
who
allele
mild
disorders
provide
forms
They
world
are
where
also
disorder from
neither
of
are
are
carriers.
Explain
the
often
symptoms.
of
unaware
Alpha
haemoglobin.
protection
against
thalassaemias
are
The
in
malaria
important
in
is
(or
was)
an
communities
the
the
from
migrants
thalassaemias
are
from
Africa
whom
their
has
and
from
the
effect
DNA
inherit
parents
the
of
the
blood
Sickle
nucleotide
gene for
structure
mild
malaria.
serious
to
that
and
disorder.
change
sequence
b-globin
and function
on
of
the
red
cells.
health
The
terms
and
codominant
dominant,
recessive
important
that
are
used
to
are
Mediterranean
the
relationships
area,
between
where
to
can
People
describe
descended
someone
as
3
problems
anaemia.
134).
from
one
carriers
cell
diagram
as
2
People
sickle
genetic
both
this
sickle
have
with
alleles. What
term
or
common.
terms
do
applied
for
you
to
think
the
should
alleles
b-globin? Justify
of
be
the
your
gene
answer.
131
5.5
Darwin
Learning outcomes
Galápagos
Evolution
On
completion
of
this
section,
be
able
state
the
the
English
be
linked
naturalist
to
and
the
name
scientist
of
Charles
whose
Darwin
journey
(1809–
around
the
to:
world

forever
you
1882),
should
will
mockingbirds
observations
made
by
a
in
the
ship
mechanism
by
HMS
Beagle
which
between
evolution
1831
and
1836
led
him
to
propose
occurs.
Darwin
On

explain
how
these
his
circumnavigation
islands
led
to
Darwin’s
conclusions
off
the
west
coast
the
of
Africa,
globe
Darwin
South
visited
America,
the
Cape
islands
in
V
erde
the
Pacic,
about
New
natural
of
observations
Zealand,
Australia
and
South
Africa.
While
on
the
Galápagos
selection.
Islands
known
in
as
the
Pacic
mocking
‘My
he
made
this
observation
about
birds
that
were
then
thrushes.
attention
was
first
thoroughly
aroused,
by
comparing
Galápagos
together
the
numerous
specimens
....
of
the
mocking-
mockingbird
thrushes,
when,
to
my
astonishment,
I
discovered
that
all
Mimus parvulus
those
one
from
Charles
species
Island
(Mimus
[now
called
trifasciatus);
all
Floreana]
from
belonged
Albemarle
to
Island
San Cristóbal
[Isabela]
to
M.
parvulus;
and
all
from
James
Island
[Santiago]
mockingbird
and
Chatham
Island
[San
Cristóbal]
belonged
to
M.
Mimus melanotis
melanotis.’
These
they
birds
are
them
on
the
Galápagos
Floreana
Española
mockingbird
mockingbird
species
M.
Mimus trifasciatus
of
now
known
distributed
South
birds
is
as
in
in
related
the
mockingbirds
the
American
were
Mimus
macdonaldi
Americas.
mainland
to
them.
Galápagos,
found
only
on
and
Darwin
–
as
realised
There
Española
and
Darwin
are
in
only
an
a
group
had
seen
that
fact
saw
island
the
four
three
as
Darwin
Mimus macdonaldi
did
Figure 5.5.1
are
widely
not
visit.
This map of the Galápagos Islands shows the
The
distribution of the four species of mockingbirds that are
endemic to these islands – found here and nowhere else
The
on
close
the
from
species
occur
resemblance
mainland
the
did
not
led
mainland
changes
amongst
sowed
populations
to
variation
islands
of
with
seed
the
for
natural
between
to
populate
isolated
signicant
share
by
Darwin
to
birds
the
the
four
mockingbirds
give
on
idea:
on
that
mockingbird
that
islands.
islands
to
big
the
different
changes
in
selection
suggest
on
enough
the
mockingbirds
his
He
with
these
other
species
individuals
then
had
stated
different
and
species
migrated
that
environments
populations
features
led
that
they
islands.
Darwin’s finches
Darwin
collected
mockingbirds,
London
related
the
by
these
species
nches
methods.
from
the
Darwin
The
on
132
John
mainland.
an
The
found
that
are
trees;
is
he
who
known
nch
ground
species
of
perhaps
nowhere
to
else
feed
best
as
an
to
species
The
food
in
closely
from
beaks
of
gathering
remove
insects
seeds.
plants
known.
known
and
studied
were
related
nches.
spines
on
than
later
they
from
foods
and
smaller
were
that
Darwin’s
cactus
animals
is
realised
different
uses
are
These
different
as
nches
the
which
visited.
signicantly
now
adaptations
other
and
nches,
(1804–81)
woodpecker
of
of
islands
were
They
tortoise
island
the
Gould
show
bark
giant
specimens
from
A
found
species
island
nowhere
that
is
endemic
else.
only
found
Module
On
his
return
evidence
and
for
animal
amongst
to
his
and
plants
England
theory
plant
and
in
and
1836,
Darwin
spent
communicating
breeders.
He
with
compiled
20
years
Genetics,
collecting
scientists,
many
2
variation
and
Did you know?
examples
of
Darwin
variation
animals.
in
the
was
particularly
variation
selection
pigeons,
pigeon
In
1858,
the
naturalist
and
collector
Alfred
Russel
W
allace
sent
essay
occur
to
that
species.
of
the
of
Species
We

Linnean
can
by
19
Natural
within

offspring
each
theory
there
that
a
ideas
1859,
have
after
organisms
were
own
on
changes
presented
Darwin’s
the
as
book
at
a
On
breeders
species
resemble
of
is
own
natural
there
their
of
years
remain
fairly
to
than
elephants
700
is
selection
competition
for
meeting
the
Origin
reproduce
ever
had
stable
large
become
the
mature;
potential
from
year
to
to
year
have
with
variation
stated
resources
that
have
the
same
for
water
,
food,
compete
for
space,
water
,
that:
between
individuals
of
the
same
means
to
territories,
ions,
obtain
nesting
light,
those
sites
carbon
resources;
and
dioxide
mates;
and,
in
animals
Mimus
A Galápagos mockingbird,
parvulus
plants
some
foc us
pollinators
competition
leads
to
high
death
rates
among
young
animals
that
Competition
starve,
are
eaten
by
predators
or
die
of
disease;
there
is
a
similar
mortality
among
seedling
plants
that
start
growing
in
same
species
do
not
absorb
enough
water
,
ions,
light
or
carbon
dioxide,
in
this
herbivores
struggle
resources
for
survive
or
are
killed
existence
to
breed
the
and
by
answer
this
differential
individuals
best
sur vival
adapted
means
to
the
on
best
their
the
best
adapted
animals
are
that
adapted
populations
conditions
good
to
resisting
disease
and
consist
existing
at
of
could
Mendel’s
convincing
case
inheritance
selection
not
paper
explain
and
for
natural
occurred
that
how
at
nding
nding
variation
understood
and
knowledge
it,
he
selection.
this
of
did
not
term
to
use
in
natural
selection.
any
food,
one
escaping
time
the
was
it
inherited.
have
was
provide
Mendelian
term
alleles
is
used
and
from
genes. All
individuals
of
the
same
mates.
might
As
foc us
those
species
Darwin
useful
obtain
not
predators,
a
alleles
Notice

–
on
S tudy

of
disease
individuals
pass
members
intraspecic
are
an
by
is
unsuitable
competition
places,
between
high
the

to
breeding
parents.
compete
eaten
even
pigeons.
S tudy

and
as
talking
that
Figure 5.5.2
species
cases,
time
follows:
ability
individuals
pair
his
spent
amongst
such
published.
observations
more
descendants
of
was
species
far
In
as
occurs
animals,
uctuations

His
all
ideas
W
allace’s
Darwin’s
–
same
London.
Selection
calculated
populations
the
and
in
producing
million
minor

Darwin
overpopulation
Darwin
much
Society
summarise
numbers

included
and
that
interested
Darwin
his
an
selection
naturalists
domesticated
Natural
natural
made
he
the
genetics
If
he
an
thought
support
would
had
even
that
for
have
differ
read
Some
more
‘blending’
have
in
the
chance
of
same
alleles
alleles
competitive
natural
the
give
edge
of
genes
those
they
genes.
individuals
that
–
the
increases
their
survival.
done.
Summary questions
1
Dene
the
term
4
island endemic
State
Darwin’s four
populations
2
Anolis
lizards
are found
throughout
why Anolis
different
to
lizard
species from
St.
Lucia
Explain
the
5
those from Jamaica.
Galapágos
theory
of
importance
Islands
natural
in
of
the
the
the
about
natural
signicance
of
each
one
the
mockingbirds
development
of
of
theory
of
natural
selection.
are
Suggest
animal
3
observations
explain
the Caribbean.
for
Suggest
and
why
and
Darwin
plant
was
interested
in
the
work
of
breeders.
the
Darwin’s
selection.
133
5.6
Natural
selection
Learning outcomes
Evolution
When
On
completion
should

be
state
able
the
of
this
section,
people
distinct
ideas:
and
explain
factors
about
idea
evolution
they
are
usually
referring
to
two

general
The
theory
of
evolution
states
that
organisms
change
over
specic
As
scientists
learnt
more
about
the
Earth
in
the
eighteenth
evolution
century

talk
big
to:
general
of
– the
you
time.
theories
(1)
how
act
environmental
as
agents
of
and
there
that
life
came
had
a
general
changed
realisation
over
that
the
Earth
was
very
old
time.
natural

The
special
theory
that
evolution
occurs
by
the
process
of
natural
selection.
selection.
Darwin
He
did
proposed
not
know
a
mechanism
how
the
by
which
variation
that
change
he
in
species
described
at
could
great
occur
.
length
was
Did you know?
inherited.
Melanism
pollution.
is
not
Insects
environments
so
they
associated
living
are
absorb
become
only
often
heat,
in
colder
melanic
warm
active faster
than
melanic forms. There
with
are
up
From
with
ideas
have
been
of
Vincent
(see
on Grenada
page
natural
published
biologists
selection.
have
combined
Many
knowledge
investigations
of
of
genetics
natural
selection
including:

industrial
melanism
in

antibiotic
resistance
the
peppered
moth,
Biston
betularia
and
in
bacteria.
non-
melanic
Natural
bananaquits
1900,
and
selection
in
action
St
The
140).
The
peppered
peppered
Isles.
It
ies
moth
moth,
at
and
Biston
night
and
industrial
betularia ,
during
the
is
melanism
found
day
throughout
settles
on
trees
the
where
British
it
is
Link
camouaged
country.
See
page
140 for
relating
selection
on
There
are
lichens
two
very
that
grow
distinct
on
bark
forms
in
unpolluted
within
this
parts
species.
of
One
the
has
experimental
fairly
evidence
against
to
the
effect
light
white
peppered
coloured
wings
speckled
with
black
that
makes
it
look
as
if
its
of
wings
have
been
dusted
with
black
pepper
.
This
form
is
well
moths.
camouaged
black
As
and
soon
is
as
predatory
against
known
any
on
as
since
lichens
the
melanic
birds
background
the
melanic
moths
they
trees.
that
so
were
on
trees.
The
other
form
is
form.
appeared
were
They
grow
they
obvious
eaten
were
against
before
they
likely
the
to
be
eaten
by
speckled
had
the
chance
to
a
reproduce.
the
In
the
With
of
These
mutant
middle
the
coal.
and
Manchester
which
easily
were
the
soot,
18th
by
The
birds
the
population
melanic
of
in
in
and
again
deposited
and
by
mutation,
more
in
eastern
on
of
but
pollution
In
the
of
burning
the
lichen
woodlands
melanic
around
peppered
moths
moths
melanics
survived
and
the
than
the
speckled
melanic
form
industrial
with
where
was
most
speckled
around
England
trees.
signicantly.
from
The
offspring
areas
killed
the
trees.
the
century
rural
the
changed
pollution
which
the
while
20th
air
more
against
left
as
environment
severe
woodlands
increased
now
dioxide,
eaten
the
the
came
more
populations
although
variety
and
melanics
of
changed,
was
camouaged
beginning
of
century,
noticed
the
composition
re-appeared
inherited.
sulphur
which
people
spotted
not
revolution
by
90%
Figure 5.6.1
was
contains
now
reproduced.
that
of
melanics
industrial
Smoke
species,
b
allele
no
there
carried
is
by
little
the
variety
made
cities.
pollution
were
up
so
over
The
has
not
pollution
prevailing
the
wind.
Speckled and melanic
The
map
shows
the
situation
in
the
mid
1900s.
Now,
with
the
decline
of
peppered moths settle on trees: a in an
heavy
industry
much
less
in
the
UK
and
the
introduction
of
Clean
Air
Acts
there
area free of air pollution and covered with
lichen; b in an area heavily polluted with
sulphur dioxide and soot
134
form
pollution
increasing
in
and
the
numbers
population
and
the
has
changed
numbers
of
with
melanics
the
speckled
decreasing.
is
Module
2
Genetics,
variation
and
natural
selection
Dark form
Industrial
Light form
areas
Glasgow
Belfast
Dublin
Manchester
Birmingham
Cardiff
Pr
London
wind
Figure 5.6.2
These maps shows the proportion of populations of peppered moth in the
British Isles that were melanics in the mid-1900s
In
this
example,
although
their
consequence
bird
effect
of
predators
was
human
due
are
to
acting
as
pollution
the
in
the
agent
of
natural
environment
as
selection
a
activity.
Did you know?
Antibiotic
Antibiotics
or
inhibit
are
the
medicines
Penicillin
inhibits
resistance
in
substances
the
works
protein
ribosomes.
produced
reproduction
1940s
by
with
kill
by
by
bacteria.
the
fungi
and
rather
some
of
with
than
bacteria
were
just
cell
the
walls.
smaller
stopping
that
developed
streptomycin
formation
combining
bacteria
and
Antibiotics
penicillin
inhibiting
synthesis
Both
of
being
kill
the
rst.
them
of
proteins
Streptomycin
sub-unit
Resistance
result
as
bind.
of
to
streptomycin
change
so
in
of
streptomycin
enzymes
is
the
ribosome
cannot
Penicillin-resistance
result
from
a
that
is
the
break
down
penicillin.
reproducing.
When
an
leaves
any
antibiotic
is
taken
the
susceptible
bacteria
are
survive
and
killed.
This
Summary questions
bacteria
competitors
so
that
make
are
use
resistant.
of
the
These
available
nutrients
in
do
the
not
body
have
any
and
1
reproduce
so
passing
on
the
gene
for
antibiotic
resistance.
Under
Body colour in
B. betularia is
normal
controlled by a gene. The allele,
circumstances
when
the
antibiotic
is
not
present,
any
bacteria
with
the
B codes for the melanic form,
gene
for
antibiotic
resistance
do
not
compete
so
well
because
producing
a
b for the speckled form. Explain
protein
that
is
not
required
puts
them
at
a
disadvantage.
It
takes
energy
how melanic forms of this species
to
replicate
plasmids
and
to
copy
genes
that
are
not
essential
if
the
appear in populations composed
antibiotic
is
not
in
the
environment.
entirely of the speckled forms.
V
ertical
transmission
parent
bacterium
binary
ssion.
these
can
be
to
As
the
passing
daughter
the
passed
is
genes
from
bacteria
for
one
on
of
during
antibiotic
species
antibiotic
to
asexual
resistance
another
by
resistance
from
reproduction
are
on
Use genetic diagrams to show the
by
results of crosses between melanic
plasmids,
forms and speckled forms.
horizontal
2
transmission .
this
may
Bacteria
include
antibiotic
often
plasmids
resistance
of
scavenge
from
great
dead
DNA
from
bacteria.
their
This
surroundings
makes
the
Explain
both
in
response
spread
of
concern.
foc us
the
these
3
mutant
advantage
cases
to
the
alleles
at
of
natural
selective
may
be
selection
agents. The
selected
a certain time.
if
in
action
the
mutations
they
provide
mutations
occur
do
not
melanic
which
the
decreased
in
the
the
Explain
British
has
Isles
mid-1900s.
how
of
moths
antibiotics
natural
act
as
selection.
appear
spontaneously
some feature
why
of
agents
In
detail
frequency
since
S tudy
in
and
and
is
an
4
Explain
can
be
how
antibiotic
transmitted
resistance
vertically
and
horizontally.
135
5.7
Natural
selection
Aspects
Learning outcomes
of
the
overproduce
On
completion
should
be
able
of
this
section,
you
the
habitat
many
to:

describe
why
heritable
important
to
life
state
to
that
natural
maintain
population
selection
constancy
and
in
explain
acts
a
discuss
to
this
are
when
as
an
natural
agent
of
and
the
for
next
in
Selection
The
mates.
in
the
such
as
the
predation,
as
environment,
disease
does
often
are
often
it
Scotia
this
are
If
at
they
individuals
or
die
of
individuals
their
are
Alleles
alleles
much
in
Species
the
between
disease.
that
population
than
individuals
These
survive
and
factors
the
most
vulnerable
compete
early
for
period
nesting
of
successful
that
In
a
are
sexually
different
variation
they
as
genes
in
get
to
pass
advantageous
reproducing
are
the
their
in
alleles
in
species,
produced
previous
on
increase
new
each
generation
generation.
selection
not
Stabilising
always
maintains
in
crab,
lead
has
to
to
has
as
over
it
Y
ucatán
largely
occurred
as
has
time
polyphemus ,
the
remained
selection
change
populations
Limulus
Canada
species
in
is
so
with
that
found
Mexico.
unchanged
the
peppered
they
in
We
for
do
the
seas
know
250
environment
moths;
not
change.
from
from
million
has
not
fossils
years.
changed.
and
Research
competition,
The
selection.
competition
predators
population.
of
horseshoe
Nova
that
of
by
is
of
a
foc us
aspects
young
There
size.
generation.
producing
more
These
more
agents
selection
change
population.
S tudy
eaten
organisms
Stabilising
acts
are
support.
population
combinations
so
how
the
frequency
how
happens

there
as
selection
sites

so
act
variation
of
is
environment
can
starve,
control
(2)
in
Sweden
on
populations
of
reed
warblers,
Acrocephalus
called
scirpaceus,
provides
evidence
for
stabilising
selection.
The
wings
of
young
selection pressures
reed
warblers,
nest.
At
Each
bird
this
reach
age
was
the
their
wing
identied
maximum
length
by
in
putting
length
a
few
millimetres
a
small
ring
days
of
after
each
around
leaving
bird
one
was
of
the
recorded.
its
legs.
Link
When
rings
The
genetic
variation
is
the
result
the
was
meiosis
pages
information
128,
84
and
to
caught
identify
in
net
specic
traps
birds
as
and
adults
their
the
information
age.
The
length
The
ringing
and
before
it
trapping
was
was
recorded
for
each
bird
that
mean
in
age
the
at
trapping
was
calculated
for
birds
of
Wing
each
wing
length
ringing/mm
at
Number
Mean
age
In
data
of
birds
shows
with
trapping/
common
name
not
related
to
crustaceans.
It
is
less
than
63
24
closely
related
to
spiders
with
the
64
72
wing
than
lengths
extremes
Records
of
the
the
length
65
130
most
of
346
167
349
for
generations
birds.
106
discovered
270
length
this
69
more
than
70
66
237
23
199
total
been
=
771
is
many
of
these
Scientists
that
responsible
68
has
297
183
67
common
wing
66–67 mm
66
conrm
256
that
136
greater
and
range.
scorpions.
a
survival
253
at
more
of
L. polyphemus
those
is
had
days
chance
its
that
wings
spite
trapped
of
as
at
66–67 mm
crustaceans.
length
table.
birds
are
was
released.
The
Did you know?
crabs
the
time
see
98.
shown
Most
on
of
and fertilisation,
identied
for further
used
were
of
between
mutation,
birds
in
for
reed
are
wing
warblers
another
stabilising
have
genes
example
selection.
so
of
Module
Directional
Peter
of
and
the
of
Rosemary
of
the
bird
on
birds
birds
the
with
before
(an
increase
to
2005
second
a
the
nches,
G.
number
of
The
drought,
The
nch
seeds
was
than
for
rate
large
quickly
beak
length/mm
mean
beak
depth/mm
selection
of
for
after
with
the
beaks,
to
reduced
able
the
had
to
rains
length/mm
mean
beak
depth/mm
bell-shaped
eat
birds
of
10.68
11.07
9.42
9.66
was
size
you
the
can
to
ground
the
became
leaving
of
had
2003
seeds
high,
the
than
decreased
beak
as
seeds.
curve
In
large
small
The
pre-1977
the
greater
occurred.
drastically
to
eat
returned,
was
presence
reproduce.
to
beak
data
The
ability
large-beaked
beaks
mean
the
offspring
depth).
Now
survived
many
died;
were
selection
larger
Birds that
died
survived.
their
beak
Birds that
the
very
medium
see
in
the
Grants
growth
discovered
of
the
beak
2002
Population
11.2
10.6
9.4
8.6
that
so
in
the
this
is
size
an
of
the
beaks
inheritable
is
related
to
in
the
2005
genes
feature.
Figure 5.7.1
Geospiza
Disruptive
In
natural
table.
mean
for
and
the
and
10.5 mm
combined
with
In
on
collected
Population
The
variation
population
bird
recovered
available.
death
with
this
that
directional
magnirostris,
individuals
drought
for
depth
4–5%
as
a
Grants
fortis
beak
a
fortis ,
Galápagos.
those
larger
G.
of
right
large
important.
ground
of
and
the
seeds
and
beaks
size
shifted
next
died
studied
Geospiza
suffered
crashed.
that
body
in
provide
population
average
few
island
have
nch,
Major
that
population
the
Only
As
the
plants
Grant
ground
Daphne
mid-1970s,
Genetics,
selection
medium
island
2
this
case
A large ground nch,
magnirostris, feeding on seeds
selection
a
species
may
be
spread
across
a
geographical
range
and
the
Summary questions
extremes
selected
are
selected
against.
in
This
different
gives
rise
places
to
two
but
the
types
populations
in
the
which
middle
may
are
change
so
1
much
that
they
are
not
able
to
Write
types
The
African
equatorial
species
seedcracker
,
forests
there
and
Pyrenestes
feeds
denitions
on
the
ostrinus ,
seeds
of
is
a
sedge
bird
that
plants.
lives
Within
in
the
small-beaked
birds,
which
have
beaks
12 mm
wide
and
feed
on
selection
this
section:
and
disruptive.
after’
are:
of
the
different
to
described
stabilising,
graphs
happens

of
interbreed.
Draw
to
‘before
illustrate
a feature
in
directional
and
what
that
shows
soft
continuous
variation for
each
seeds
type

large-beaked
hard
birds,
which
have
beaks
15–20 mm
wide
and
feed
of
2
seeds
Explain
shows

mega-beaked
birds,
which
have
even
larger
beaks
so
can
feed
on
the
parents,
wet
season
all
seeds
are
abundant
and
all
bird
forms
feed
on
variation
of
seed.
In
the
dry
season
when
food
becomes
scarce
the
specialise
resources
seeded
on
the
other
S.
sedge
on
the
seeds
between
species
soft-seeded
soft
seeds.
racemosa.
could
yet
the
to
which
they
are
best
adapted
be
different
an
Birds
Scleria
sedge
The
early
them.
verrucosa ,
goossensii
mega-beaked
with
stage
populations
S.
Large-beaked
beaks
in
that
whereas
and
birds
may
so
in
their
the
depth
isolated
on
small-beaked
on
selection
become
specialise
broaden
feed
intermediate
disr uptive
birds
to
to
diet
even
do
give
pattern
not
form
a
feed
include
seeds
survive.
new
remains
adult
the
to
same
generation
in
species.
hard-
birds
to
or
the
dividing
harder
two
within
generation
many
food
generation
than
three
from
forms
new
all
population
types
each
variation
seeds.
of
In
how
more
very
its
hard
selection.
on
more
of
This
3
Predict
of
the
have
effects
sedge,
on
African
dry
the
that
extinction
S. verrucosa,
populations
seedcracker,
of
might
the
P. ostrinus,
in
seasons.
species.
137
5.8
Species
and
Learning outcomes
On
completion
of
this
section,
how
Biological
species
We
the
have

be
able
dene

the
discuss
term
term
the
species
the
that
each

species
group
of
without
really
organisms
advantages
of
isolating
the
unchanged
over
be
and
their
and
not
to
like
this
biological
of
the
fertile
how
allopatric
speciation
breed
species
and

together
from
same
other
time.
that
specimens
occur.
dead
and
to
By
contrast
they
concept
produce
species.
species,
offspring.
single

it
Did you know?
is
Swedish
biologist, Carl
developed
the
in
thought
response
to
that
species
changes
in
states
a
This
see
biologist
is
not
collected
some
T
o
are
fertile
that
all
individuals
if
may
two
must
always
see
or
if
naming
very
if
a
result
system.
into
Each
specic
this
are
of
of
a
species
are
reproductively
individuals
will
mate
are
members
together
and
give
because:

fossil

some
species
cannot
breed
species
reproduce
from
to
observe
in
the
the
by
asexually
parthenogenesis
(unfertilised
wild,
offspring
the
next
egg
cells
give
rise
to
generation).
to
fertile
these
concept.
difculties
species
name
They
dene
most
scientists
species
by
the
use
the
morphological
possession
of
common
a
features
as
of
morphology
(outward
appearance),
behaviour
,
has
physiology,
throughout
are
organisms.
organisms
and
check
they
distinctive
hierarchical
difcult
behaviour
alone
species
classied
and
more
they
possible
be
known
offspring
binomial
As
generic
used
that
Linnaeus
see
a
features
specimens
mating
let
He
Darwin
changed
or
system for
Linnaeus
environment.
isolated
separate from
other
(1707–78)
it.
common
biological
mechanisms
species
sympatric
The
dening
sharing
concept
keep
explain
a
could
able
list
term
mean
remained
Mayr ’s

to
to:
disadvantages
species
used
evolve
you
the
should
they
biochemistry
and
anatomy.
used
book.
Isolation of different
There
are
various
methods
species
that
prevent
individuals
from
different
species
Did you know?
breeding
in
The
biological
proposed
scientist,
by
species
the
Ernst
concept
naturalist
Mayr
the
with
table
each
other
.
These
isolation
mechanisms
are
summarised
opposite.
was
and
(1904–2005)
in
Speciation
1942.
New
species
happens
is
Allopatric
separated
occurs
when
Over
S tudy
that
foc us
time
they
populations
isolated
by
their
of
shrimp
behaviour.
are
was
very
are
put
of
3
The
process
by
which
this
when
different
more
populations
geographical
populations
are
of
a
species
areas.
in
the
are
physically
Sympatric
same
speciation
geographical
migrate
pressures
lead
to
changes
interbreed
Alpheus,
but
they
with
were
years
when
to
ago.
at
in
the
with
the
a
one
they
that
when
on
the
area.
do
side
these
not
exposed
have
to
of
two
of
occur
species,
within
so
that
sometimes
a
population.
individuals
occurs
are
between
Usually
not
the
extent
different
to
is
the
the
isthmus
populations
an
abrupt
interbreed.
species
of
Panama
mate.
this
able
to
left.
Populations
isthmus
either
from
and
are
they
population
population.
females
another
area,
area
isolated
Populations
and
new
the
original
separated
males
‘snap’
occupy
compared
speciation
may
a
or
million
together
in
occurs
species
may
similar
,
Hybridisation
138
a
shrimp,
Sympatric
change
species.
speciation
this
Speciation
existing
speciation
two
two
cannot
formed
are
as
in
selection
snapping
These
are
the
individuals
different
from
speciation
and
Allopatric
If
arise
known
of
plant.
Module
Isolating
mechanism
Pre-mating
isolation
features
such
separate
or
seasonal
occurs
to
structural
organs
of
different
of
a
so
the
three
parts
they
different
differ
males
times
of
two
between
sub-species
of Africa
species
and
female
do
not
males
mate
show
mating)
differences
males
mean
that
and females
species
are
the
hybrid
fertilisation
hybrids
offspring
prevented
does
to
are
sex
exoskeleton
of
pair
those
of
occur
sperm
the
of
in
crosses
develop
(often
because
chromosomes
cannot
lizards
do
not
of
and
chromosome
fertile.
arthropods
of
male
same
An
and
in
of
one
this
saltmarshes.
species,
S.
Spartina
alterniflora
that
sterile
century
S.
occurred
S.
individuals
able
to
doubles
breed
by
speciation
In
the
a
is
UK
maritima
(2n = 62),
hybridised
townsendii
to
anglica
For
and
double
(2n = 62)
its
to
grow
between
between
gives
sterile
are
produced
‘t
with
failure
either
of
polyploidy
in
the
early
(2n = 60).
was
with
parent.
meiosis
in
cord
19th
The
introduced
the
which
chromosome
and
key’
–
only
together’
is
immobilised
in
tract
pollen
tubes
on
stigma
of
goats
horse
and
sheep
(female)
and
donkey
(male)
no
viable
males
they
North
native
However
,
spread
number
to
a
plant
there
in
the
produce
vegetatively.
to
become
foc us
thought
that
speciation
is
a
was
gradual
process.
S. anglica is
an
American
accidently
species
with
produced
become
grass,
century
are
of
a
species
that
evolved
middle
quickly
over
just
a few
years.
the
Polyploidy
the
fertile
species,
Summary questions
speciation
other
‘lock
genitalia
mule
to
occur
hybrids
must
be
fertile
and
able
to
1
with
a
Drosophila melanogaster mates
D. simulans,
(2n = 124).
sympatric
breed
that
head
species
very
of
of
males
D. americana
example
species,
and
in
other
displays
ignore
gives
Drosophila viridis
long,
only
pollen
each
meiosis)
viable
not
number
example
grows
the
and female
species
Darwin
that
release
dewlap
S tudy
the
different
pollinate
recognise
species
displays
of
cross
when
no
if
in
geographically
in California
so
same
arrangement
incompatible
not
sterile
homologous
sterile
elephants
methods
embryo fails
are
of
separated
pine
different
different
hybrids
of
anolis
of
pollen fails
The
are
and April
of female
of
selection
bobbing
prevented
breeding
natural
never
and females
signals
(assortative
production
at
rituals
so
respond
isolation
lakes,
February
courtship
mechanical
rivers,
year
species
post-mating
and
meet
breeding
behaviour
as
lowlands, forests
populations
rarely
the
reproductive
variation
methods
mountains,
or
Genetics,
Example
geographical/ecological
temporal
2
such
hybrids,
but
not
breed
with
either
parental
Dene
the
term
biological
species.
species.
A
hybrid
that
is
Lonicera
which
so
a
is
maggot
feeds
has
does
be
a
either
to
survive
parental
hybrid
that
on
feeds
on
which
compete
feed
with
in
its
species.
between
the
The
on
either
and
hybrid,
the
habitat
An
species
blueberries,
snowberries.
maggots
not
adapted
with
which
that
zephyria
also
shared
y
has
maggot
and
must
not
fruits
parent
have
is
Rhagoletis
R.
as
R
a
habitat
2
the
with
mendax
honeysuckle,
Explain
to
mendax ,
zephyria,
known
of
or
example
why:
apply
concept;
a
species
×
Lonicera,
in
the
ii
i
it
is
often
biological
the
difcult
species
morphological
concept
is
easier
to
apply
practice.
species.
3
Distinguish
and
between
sympatric
allopatric
speciation.
139
5.9
Variation
and
Many
Learning outcomes
some
On
completion
of
this
section,
natural
scientists
of
these
be
able
investigations
analyse
are
examples
presented
of
selection.
The
results
of
here.
experiments on
peppered
moths
to:
Bernard

investigated
summary
you
Kettlewell’s
should
have
selection
data
about
Kettlewell
investigated
the
effect
of
predation
by
birds
as
the
natural
selective
agent
in
maintaining
populations
of
peppered
moths
in
the
selection
1950s

apply
knowledge
understanding
of
and
to
investigations
explain
into
and
forms,
results
selection
area
of
suggest
how
variation
investigated
agents
of
might
to
in
lichen.
His
trapped
and
and
After
results
are
a
a
in
and
then
wood
few
the
reared
released
in
days
a
melanic
them
rural
he
in
area
used
a
and
a
non-melanic
wood
where
moth
in
the
trap
an
industrial
trees
to
were
recapture
the
table.
in
1
populations
He
them
Birmingham
covered
moths.

1970s.
marked
Describe
and
explain
the
data
shown
in
the
table.
be
discover
Kettlewell
the
feeding
selection.
the
observed
on
bark
of
predation
the
peppered
the
by
the
trees.
birds
behaviour
moths
His
was
of
that
predatory
were
observations
the
agent
of
birds
least
well
provided
selection
Number of
peppered
lmed
in
them
camouaged
evidence
both
Melanism
Site of
and
is
that
against
visual
areas.
not
unusual
in
animal
moths
species.
An
example
is
the
variation
woodland
within
non-melanics
melanics
populations
bananaquit,
Grenada
non-polluted,
marked
and
released
496
473
the
St
flaviola,
Vincent.
The
on
more
969
form
is
mainly
yellow
area
with
recaptured
62
30
some
%
of
marked
moths
12.5
6.3
only
and
industrial
marked
and
released
64
154
16
82
98
of
marked
moths
25.0
52.3
of
Suggest
how
discover
on
Sample
you
how
Grenada
it
and
Percentage of
Percentage of
yellow
unbanded
might
is
investigate
inherited
St
and
in
sample
in
sample
1
12
Banded
on
3
12
79
They
pink
others
do
and
alleles
at
not.
two
83
with
in
birds
bannaquits
in
to
populations
nemoralis
leaf
and
litter
C.
hortensis,
and
exist
in
yellow.
three
Some
different
ground
snails
colours:
These
two
features
have
loci
on
are
bands,
controlled
by
In
a
from
survey,
different
C.
woodland
nemoralis
snails
where
leaf
the
litter
21
dark
brown
and
colour
adjacent
is
more
grassland
variable,
but
where
the
mostly
14
yellow
3
mates
colour
.
in
amongst
separate
collected
background
58
no
mating
70
was
2
is
a
than
77
were
1
shade
There
maintained
Cepaea
ground
chromosomes.
grassland
is
for
dry
have
88
brown,
21
same
the
disturbed
assortative
form
low
snails
snails,
the
vegetation.
2
each
at
whereas
on
Melanics
birds.
for
forest
on
are
snails
live
woodland
it
live
preference
melanism
how
moist
and
they
Vincent.
Banded
snails
the
in
altitudes
yellow
which
2
Melanic
black
Vincent
habitat.
evidence
recaptured
St
forms
stronger
the
%
and
high
lowland
recaptured
marking.
completely
found
yellow
218
area
Habitat
are
Grenada
recaptured
polluted,
black
92
forms
22
of
and
green.
yellow-shelled
three
140
Coereba
and
common
rural
of
total
samples
The
table
snails
from
and
each
shows
the
unbanded
area.
percentage
snails
in
Module
These
results
are
very
similar
to
those
obtained
by
surveys
in
2
Genetics,
variation
Birds
over
known
birds
hold
shells
are
the
broken
the
as
in
found
centre
snail
their
around
brown
each
shells
are
common
beaks
the
snails
of
and
stones.
were
the
A
them
Equal
collected
habitat.
around
predators
strike
made
each
nemoralis .
of
marked
was
in
C.
numbers
and
count
stones
of
against
a
stone.
banded
before
after
habitat.
foc us
yellow
being
a
few
The
Look
The
online for
snails
Broken
and
photos
of
Cepaea nemoralis
C. hortensis in
their
banded
and
natural
habitat.
released
days
table
on
shows
results.
Habitat
Banded yellow
grassland
23
76
woodland
68
30
3
selection
years.
thrushes
them
unbanded
into
many
natural
similar
S tudy
habitats
and
Use
the
information
maintain
different
Predation of
to
shells
explain
types
of
‘spaghetti
C.
Unbanded dark
how
selection
nemoralis
worms’
by
in
pressures
the
two
shells
act
to
habitats.
birds
Figure 5.9.1
These snails with different
banding patterns are all members of the
Y
ou
can
test
the
effect
of
visual
predation
by
putting
out
food
for
birds.
same species, Cepaea
Scientists
have
predation
by
making
brown
on
each
brown
and
tray
eaten
recorded.
by
The
Guppies
Guppies,
of
be
an
with
birds.
results
The
are
of
about
in
of
the
on
the
‘prey ’
half
theory
selection
and
painted
that
by
food
grey,
were
throughout
the
reticulata,
Caribbean.
Background
Number of
Percentage of
colour
‘prey’
‘prey’
effects
of
predation
on
brown
green
brown
eaten
147
118
55.5
44.5
green
56
72
43.8
56.2
brown
62
31
66.7
33.3
grey
were
table.
are
small
David
sh
that
Reznick
has
live
populations
of
studied
these
Describe
the
The
Aripo
river
guppies
system
living
in
in
sizes;
they
rivers
also
predation
with
predators
grow
up
faster
and
mature
predators.
reproduce
at
a
younger
age
than
those
in
worms’
shown
because
Guppies
they
are
Explain
how
in
rivers
with
predators
breed
as
soon
at
risk
of
being
eaten.
The
moving
individuals
from
each
population
out
and
putting
them
which
them,
did
others
not
did
have
not.
guppies.
The
Some
of
experiments
these
were
were
moved
from
rivers
with
new
rivers
designed
predators
you
the
the
a
would
experiment
effect
population
so
had
over
of
to
selection
to
of
‘spaghetti
time.
predators
These
are
all
examples
of
that
selection,
populations
table.
into
6
in
the
investigations
worms’
rivers
in
as
on
involved
data
rivers
nd
possible
the
‘spaghetti
at
continue
without
explain
of
T
rinidad.
5
smaller
and
sh
on
in
eaten
had
4
the
eaten
green
placed
pieces
in Trinidad
Poecilia
hortensis
visual
ground.
the
numbers
the
test
pastry
were
placed
pieces
until
to
agent
food
were
green
left
the
method
aluminium
and
20
and
could
a
coloured
Sheets
and
20
been
birds
different
colouring.
green
developed
rivers
not
speciation.
without
Explain:
predators,
and
from
rivers
without
predators
to
those
with
predators.
As
a
a
control,
rivers
populations
with
lacking
were
predators,
moved
and
the
from
same
rivers
was
with
done
for
predators
to
populations
how
speciation
over
a
how
you
from
few
sh
without
and
were
b
sexual
were
monitored
predators
populations
and
had
for
body
maturation
smaller
adopting
the
occurred
matured
changed
different
eleven
size
of
later;
earlier
.
to
strategies
years.
the
Over
guppy
in
This
maximise
depending
rivers
showed
their
on
that
time
population
with
that
chances
the
in
had
can
of
presence
show
has
that
occurred.
rivers
increased
predators
the
occur
generations
rivers
predators.
speciation
The
can
different
the
sh
guppy
reproduction
or
absence
by
of
predators.
141
5.
10
Practice
exam-style
Variation
This
section
contains SAQs
selection. You
accompanies
can nd
this
on variation
MCQs
on
and
and
the CD
questions:
natural
natural
c
selection
It
that
is
as
book.
thought
T. bicolor
Explain
given
1
a
Describe
the
differences
between
the
b
and
Explain
how
variation
of
the
a
NAMED
genetic
differs from
that
as
seen
of
of
6
Outline
for
2
a
Explain
of
the
continuous
a
of
the
inheritable variation
advantages
to
crop varieties
c
modern
which
disadvantages
uniform
crop varieties
Suggest
reasons for
breeds
and
of
livestock,
Barbados
are
State
agriculture
of
genetically
of
over
keeping
such
blackbelly
growing
large
environment
many
of
land.
different
as Jamaica
sheep, for
b
Explain
locus,
loci
c
and
can
Explain
for
how
ii
examples
on
i
the
the
the
the
natural
of
the
Hope
cattle
the future
effects
phenotype
interaction
interaction
inuence
the
of
of
of
of
a
Dene
b
With
the
term
syndrome,
and
c
of
problem
in
elsewhere
alleles
of
at
at
an
by
one
of
different
African
the
The
b
phenotypic variation
the
cell
anaemia
difference
and
cell
deletion
the rst
iii
the
triplet
iv
the
addition
the
a
between
gene
of Africa
and
that
7
a
as
is
a
serious
among
are
health
people
descended from
Tiaris bicolor,
the Caribbean
and Colombia.
Explain
It
in
is
is
and
related
wing
T. bicolor on
investigated,
how
it
is
on
as
142
occur
to
an
sequence
if
the
the SECOND
base
to T
base
pair T
at
the
triplet
changes from G
do
not
called
are
change
neutral
substitution
the
gene
how
the
to C.
the
amino
acid
coded
mutations. Other
types
and frameshift
mutations
behaviour
small
pregnant
males
a
you
of
have
or
described
neutral.
chromosomes
the
to
length
a
cause
of
Down’s
syndrome.
is
has
a
larger
her
He
marine sh.
unusual
and
have
biological species
as
it
brood
brood
the
Reproduction
male
pouch
on
that
its
eggs
sperm
into
onto
the
the
tail.
Larger
seahorse
male’s
eggs
in
becomes
pouches. A female
unfertilised
releases
is
and
brood
they
are
He
keeps
the
developing
young for
a
period
coasts
several
weeks
and
then
gives
‘birth’.
Darwin’s
in
a Caribbean
recorded
possible
that
is
small
male
and
the
a female
and
to
island
seahorse
remain
to
populations
on
season. Within
a
together
as
a
population
a
select
males
by
size.
Large females
pass
their
to
the
brood
pouches
of
large
males
and
small
presented.
determine
belongs
mating
island
if
the
pass
their
eggs
to
small
males. The
selection
the
mates
in
this
way
is
known
as
assortative mating.
same
the South American
breed.
mainland.
the
the
are
Very few
species
acid
translation
substitution, frameshift
seahorses
of
population
of
base
term
females
b
amino
in
changes from A
of
the
eggs
be
triplets
deleted
Dene
females
would
DNA
gene for
Islands.
how variation
of
is
meiosis
pair for
population
the
the rst
during
transfers
grassquit,
the Galápagos
Describe
are
mutation
Explain
a
A
a
that
Classify
of
of
of
base
third
triplet
fertilised.
nches
to
mutations
ii
Seahorses
anaemia
world
throughout
of Venezuela
of
the
Down
populations.
black-faced
bird found
gene
a
pouch.
5
of
mutations.
organism.
mutation.
sickle
parts
in
sequence
strand
produced
i
in
sickle
explain
why
on
mutation
to
chromosome
Explain
have
triplet:
Mutations
selection.
reference
may
now found
the
organism.
alleles
phenotype
importance
an
of
c
4
a
happens
peptide
beginning
Describe TWO
of nch
genetically
areas
v
a
what
the
farming.
3
is
template
following
the
population
CTA ATG TAC CCA ACC TAC CTA AAG
DNA
Outline
small
species
such
octapeptide:
uniform.
b
a
14
birds
Islands.
islands.
The following
selection.
the
having
importance
the
of
To answer this question you will need to use the DNA
on
natural
such
to
population
the Galápagos
genetic dictionary on page 67.
discontinuous
variation.
c
small
in
organism.
control
a
continuous
discontinuous variation
phenotype
how
rise
those
variation
that
colonised
seahorses
of
intermediate
size
survive
and
Module
Two
closely
related
species
Hippocampus erectus
same
coastal
length
of
waters
120 mm,
and
of
of
seahorse,
H. zosterae
Florida.
H. zosterae
The
are found
H. erectus
has
a
mean
has
a
in
the
2
table
females
Genetics,
summarises
of
these
Name
the
type
of
speciation
that
of
Habitat
species
exist
in
the
same
the features
of
selection
males
and
Body
colour of
Retina
in
eyes
males
of females
blue
detects
when
shallow
two
natural
mean
length
occurs
and
species.
20 mm.
b
variation
geographical
water
blue
area.
light
c
Use
the
information
erectus and
another
provided
H. zosterae
species
of
may
to
explain
have
how
H.
evolved from
Hippocampus in
the
coastal
deep
waters
d
of
Explain
how
isolated
8
sensitivity
species
other
Gonorrhoea
is
a
tests
than
remain
by
red
detects
red
light
bacterial
are
reproductively
assortative
Body
mating.
and
colour vision
Females
with
prefer
select
the
are
both
males
inherited
that
they
mate
disease. Antibiotic
carried
taken from
colour
features.
out
on
samples
people
with
and
coloured
males.
of
a
bacteria
water
Florida.
gonorrhoea
i
The
ancestors
of
red
and
blue
cichlid sh
were
to
brown.
ensure
that
they
are
treated
with
an
appropriate
State
how
the
different
body
colours
of
the
antibiotic.
males
a
State
how
bacteria
become
resistant
arose.
to
ii
Suggest
the
advantages
of
different
cichlid
antibiotics.
sh
b
Explain
how
antibiotic
resistance
is
b
from
one
bacterial
cell
to
being
able
Many
species
of
Explain
why
it
is
important
to
carry
out
tests
before
blue
and
have
red
evolved
light.
prescribing
a
the
information
provided
in
to
lakes
explain
antibiotic
how
sensitivity
detect
cichlid sh
others.
in Africa. Use
c
to
transmitted
course
speciation
may
have
occurred
in
these
lakes.
of
c
Lake Victoria
receives
considerable
pollution from
which
the
antibiotics.
the
d
Antibiotic
resistance
is
a
serious
medical
surrounding
cloudier
worldwide. Suggest
ways
in
which
this
and
reduces
be
a
Dene
The
plant
makes
penetration
water
of
and
explain
the
likely
blue
long-term
overcome.
effects
9
the
problem
light. Suggest
may
area,
problem
the
term
speciation
and
of
blue
the
cloudy
water
on
the
species
of
red
cichlid sh.
Euphorbia tithymaloides is found
11
throughout Central America
and
the Caribbean.
It
a
Explain
why
body
mass
is
an
example
of
is
continuous variation.
thought
that
the
plant
spread from Central America
Three
in
two
directions
–
along
the
north via Cuba
separate
islands
Jamaica
and from
the
east via Trinidad.
adjacent
islands
interbreed
successfully,
but
in
the
north-east
there
are
two
do
not
Explain
across
of
the
world
time. The
mass. At
different
were
studied
researchers
over
collected
a
long
data
the
beginning
body
mass
of
all
on
the
showed
a
normal
distribution
and
the
mean
interbreed.
body
b
on
populations
mice
that
mice
in St.
body
Croix
of
Populations
period
on
populations
and
the
signicance
of
mass
of
each
population
was
about
the
same.
the following
At
the
end
of
the
study,
these
results
were
obtained:
statements.
Population A
i
Populations
on
adjacent
islands
no
change
to
the variation
in
body
interbreed
mass
successfully.
Population
ii
There
are
two
populations
on St Croix
that
B
the
mean
fewer
not
Explain
natural
10
Many
why
heritable variation
is
species
of
in Africa. Some
others
light
cichlid sh
live
in
that
that
but
more
with
larger
mice
there
were
many
much
larger
small
mean
mass
mice,
but
mice
none
and
with
many
the
live
in
species
deeper
penetrate
live
in
water. The
live
in
water
lakes.
Blue
shallow
does
the features
not
the
original
population.
Draw
graphs for
populations A,
B
and C
to
show
water
wavelengths
inuence
light
of
Lake
the variation
in
body
at
the
mass
at
the
beginning
and
of
the
end
of
study.
of
c
sh
and
important for
b
and
increased,
mice
selection.
different
Victoria
small
interbreed.
Population C
c
mass
do
Name
the
type
of
selection
that
occurred
to
each
penetrate
population.
far
into
lake
water;
red
light
penetrates
much further.
143
3
Reproductive
1.
1
Asexual
biology
reproduction
Asexual
Learning outcomes
reproduction
organism
On
completion
should
be
able
of
this
section,
you
this
some
to:
by

dene
the
way
terms
without
form
limited
random
reproduction and
binary ssion
budding
in
yeast
and
variation
of
gametes.
genetically
amongst
In
new
All
the
identical
the
and
from
individuals
organisms.
organisms
prokaryotes
individuals
in
a
eukaryotes
single
formed
There
clone
a
that
in
may
is
replication
be
caused
cells
divide
and
replication
is
usually
free
from
of
DNA
errors.
in
bacteria,
number
in
Spirogyra
in
mitosis
and
types
occurs
of
so
that
daughter
chromosomes.
This
cells
receive
maintains
the
In
genetic
same
stability.
Aiptasia,
Examples
of
asexual
reproduction
are:
and
Rhizopus.

binary
ssion

budding

fragmentation

spore
in
food
These bacteria are dividing
and
in
as
and
Aiptasia
Spirogyra
in
in
but
the
circular

the
two
in
sea
anemone)
lamentous
nigricans
in
(a
alga)
mould
fungus).
prokaryotes
prokaryotes,
some
fission
larger
.

(a
bacteria
shares
binary
grow
(a
Rhizopus
reproduction
reproduction
eukaryotes
known
bacteria
yeast
Binary fission
Asexual
in
production
Asexual
Figure 1.1.1
of
of
clone
describe
spore formation
production
fusion
clone
mutation.
before
eukaryotes,
fragmentation
the
the
asexual
occurs

a
is
as
each
When
such
similarities.
a
chromosome
cell
cell
as
This
splits
reaches
bacteria,
type
into
a
of
two.
certain
is
simpler
than
reproduction
Bacterial
size
it
cells
starts
to
in
is
absorb
divide:
replicates
by binary ssion
chromosomes
separate
while
held
on
to
the
cell
surface
membrane
Link
Remember
have
a
that
nucleus
chromosomes
prokaryotes
or
do
those
two

cell
wall

the
cells
see
page
cell
membranes
material
is
form
formed
across
between
the
the
middle
new
of
the
cell
remain
attached
for
a
while
and
membranes
then
split
apart.
of
Some
eukaryotes,
new
not
linear
like

bacteria,
such
as
Escherichia
coli ,
divide
every
20
minutes
under
32.
optimum
conditions.
Asexual
reproduction
in
eukaryotes
Did you know?
Budding
Multiple ssion
occurs
in
Y
east
organisms;
the
while
malarial
many
tiny
picked
up
blood
divides
stages
a female
when
S tudy
red
parasite
infective
by
mosquito
in
into
that
on
cells
are

the
16

the
nucleus
blood.
page
foc us
divide
much
by
that
does
binary ssion
smaller
144
yeast
than
the
as
not
the
bud
parent
linear
remains

a
in
size
but
do
not
divide
equally
in
half.
At
a
certain
size:

one

the
is
cell.
chromosomes
begins
intact
to
and
replicate
divide
does
not
by
mitosis,
break
up
as
but
the
shown
nuclear
in
the
membrane
diagram
on
79
small
of
swelling
the
bud
scar
Remember
grow
cells
Anopheles
it feeds
in yeast
some
on
appears
daughter
remains
the
at
nuclei
attached
parent
yeast
the
side
enters
for
cell.
a
of
the
the
bud
while
and
yeast
then
cell
to
breaks
form
off
a
bud
leaving
a
bud
Module
Budding
in
a
3
Reproductive
biology
Aiptasia
Aiptasia
is
budding
called
sea
anemone,
which
reproduces
asexually
by
a
form
of
bud
pedal
laceration.
Small
groups
of
cells
from
the
base
of
the
separates
animal
grow
animal
and
feed
into
each
small
then
buds.
After
develops
a
about
mouth
a
week
these
surrounded
separate
by
from
tentacles
so
the
it
can
itself.
Fragmentation
in
bud
Spirogyra
parent
yeast
Spirogyra
grows
is
on
length.
one
the
Any
of
many
surfaces
cell
in
of
the
types
of
ponds.
chain
multicellular
,
A
can
short
single
enlarge,
lamentous
chain
divide
by
of
alga
cells
mitosis
grows
to
cell
that
in
form
two
Figure 1.1.2
cells
of
and
the
make
the
laments.
chain
New
longer
.
Growth
laments
form
does
when
not
lines
happen
of
just
weakness
at
the
ends
These yeast cells are
budding. The nucleus divides and one of
the daughter nuclei enters the bud before
develop
it breaks off.
between
When
cells.
Any
conditions
disturbance
are
perfect
to
for
the
laments
growth,
algae
causes
like
them
Spirogyra
to
break.
can
cover
the
Did you know?
surfaces
of
owering
freshwaters
plants
also
in
a
thick
reproduce
growth
by
called
blanket
fragmentation,
for
weed.
Many
example
the
Rhizopus nigricans and
Mexican
Hat
plant,
K alanchoe
daigremontiana
grows
tiny
soft
around
its
leaves.
After
a
while
these
break
off
and
fall
to
the
rots
Leave
some
damp
in
sweet
damage
cannot
in
cause
potatoes. These
ground.
fungi
Spore formation
R. tritici
plantlets
be
the
potatoes
so
they
sold.
Rhizopus
bread
exposed
to
the
air
for
30
minutes,
place
in
a
Petri
Summary questions
dish
of
and
look
mould
over
at
it
the
every
day
surface
for
of
the
the
next
bread.
few
This
days.
is
Y
ou
bread
will
see
mould,
a
a
growth
type
of
1
fungus.
The
common
bread
mould,
hyphae,
which
spread
Rhizopus
nigricans ,
has
Dene the following terms:
branching
asexual reproduction, binary ssion,
laments,
or
over
the
surface
and
grow
into
the
budding, fragmentation
bread.
black
If
you
pin
heads.
reproduction
mass
of
look
for
white
at
the
These
the
growth
are
the
fungal
with
a
hand
structures
body,
the
lens
you
carrying
mycelium,
can
out
see
lots
of
2
asexual
which
you
can
see
as
According
theory
a
laments.
from
of
Fungi
exhaust
their
food
supplies,
often
very
quickly,
so
they
need
to
spores

hyphae

the
to
colonise
known
as
new
sources
as
sporangiophores
of
each
sporangiophore
mitochondria
haploid
nuclei
move
from
the
up
hyphae
up
into
the
during
the
cell
to
form
a
into
the
this
cycle.
happens.
Describe
the functions
air
of
the
sporangium
sporangium
and
in
asexual
reproduction
divide
R. nigricans:
sporangiophore,
mitosis
mitosis,

of
how
of
by
derived
number
increases
Describe
following

are
prokaryotes. The
follows:
grow
swells
endosymbiosis
to
3
tip
the
mitochondria
interphase
produce
and spore
tiny
the
columella
–
the
sporangium
an
extension
of
the
sporangiophore
–
pushes
up
it
from
the
rest
of
the
cytoplasm

a
forms
around
a
group
of
several
Suggest
nuclei
to
form
a
how
forms
around
each
the
you
might
contamination
of
spore
stored
wall
spore.
mycelium
prevent

and
into
4
separating
sporangium
sweet
potato
tubers
by
spore
R. nigricans

when
the
spores
are
ready,
the
sporangium
splits
open
and
the
spores
5
dry
and
are
blown
away
in
air
Discuss
the
advantages
disadvantages
Fungal
light;
Many
spores
most
may
will
be
not
organisms,
carried
land
both
on
thousands
a
food
prokaryote
of
source,
and
miles
so
as
there
eukaryote,
they
is
are
great
produce
so
small
and
considerably
in
their
structure
so
the
term
spore
is
spores.
difcult
such
as
are
best
thought
of
as
microscopic,
reproductive
nuclei.
are
bodies
and
one
or
more
They
often
dispersed,
but
The
as
some
are
for
surviving
harsh
conditions
and
not
really
sea
anemone,
in
the
same
way
as
the
spores
of
R.
nigricans.
The
owering
plants
are
spores
although
they
are
not
released
embryo
nor
can
into
very
surviving
hash
conditions
(see
page
marine
aquaria.
quickly
spread
are
aquaria
causing
harm
sacs
other
animals.
Suggest
why
it
they
spreads
for
is
by
for
to
of
Aiptasia
introduced
not
throughout
dispersal
algae.
contain
It
always
and
dene.
accident
cytoplasm
microorganisms,
They
to
that
asexual
bacteria, fungi
occasionally
They
of
reproduction for
wastage.
6
vary
and
currents.
so
easily.
151).
145
1.2
Asexual
reproduction
Many
Learning outcomes
owering
reproduction
On
completion
should
be
able
of
this
section,
individual
you
for
to:
or
reproduction
outline
asexual
reproduction
in
explain
the
vegetative
role
of
meristems
owers.
spreading.
as
it
involves
vegetative
growth
Propagation
Plants
can
known
is
produce
a
vegetative
producing
rather
word
new
as
new
than
growth
meaning
individuals
by
leaves,
e.g.
K alanchoe
daigremontianum
and
African
violet,
in
ionantha
reproduction

describe
of
is
from:
Saintpaulia

involving
or
propagation
modication
This
plant


by
asexually.
plants
a
growth
owering
reproduce
vegetative
plants
multiplication

plants
in flowering
vegetative
stems,
e.g.
Irish
potato,
Solanum
tuberosum ,
and
ginger
,
Zingiber
propagation
ofcinale
in
crop
plants


describe
how
to
take
roots,
e.g.
breadfruit,
Artocarpus
altilis ,
and
dandelion,
Taraxacum
cuttings
ofcinale

describe
the
process
of
tissue
Ginger
plants
have
a
swollen
horizontal
stem
known
as
a
rhizome.
The
culture
stem

describe
the
hormones
use
in
propagation
of
main
plant
buds
vegetative
and
tissue
culture.
has
short
root.
at
tissue,
the
can
Eventually
Link
Structures
nutrients
Meristematic
tissue
consists
cells
that
the
animal
page
stem
are
divide
equivalent
cells
as
as
the
through
over
grow
on
grow.
soil
and
fragment
are
from
the
on
the
cover
into
swollen
unfavourable
it
as
rhizome.
These
branches
the
will
that
buds
leaves
rhizomes
survival
leaf
provide
rhizome
such
for
to
roots
from
where
grows
spread
buds
several
with
of
the
year
have
to
too
referred
store
to
rhizome
plants.
reserves
when
it
is
and
too
dry
or
too
cold
for
growth.
Most
structures
that
reproduce
are
materials
like
for
this.
Structures,
such
as
rhizomes,
tubers
and
bulbs,
perennation
on
76.
Plant
The
hormones
growth
substances
types
of
and
that
development
are
often
of
called
plants
plant
are
inuenced
hormones.
by
There
growth
are
three
main
hormone.
Type of
plant
Example
Source
hormone
the
auxin
indolyl
acid
acetic
within
Effects on
growth
plant
shoot
apex
stimulates
(IAA)
of
cells
cell
by
walls
absorbs
elongation
‘softening’
so
stretched
they
when
are
cell
water
Did you know?
The Gros
was
Michel
attacked
known
as
by
variety
of
a fungal
Panama
cytokinin
kinetin
root
apex
gibberellin
gibberellic
roots
acid
young
stimulates
cell
stimulates
cell
in
(GA
)
and
leaves
elongation
is
grown
in
new
strain
of
all
over
(tropical
race four)
the Cavendish
plant
in
the
variety
South-East Asia
spread
to
are
used
to
control
the
growth
of
crop
auxin
naphthaleneacetic
the Caribbean
for
acid
(NAA)
is
used
as
a
rooting
cuttings
gibberellins
are
sprayed
on
seedless
grapes
in
California
to
increase
may
size
of
each
grape
and
increase
the
distance
between
grapes
and
reducing
chance
of
disease
spreading
through
the
crop
Central America.

146
plants:
has
and
the
well
hormones
that

emerged
growth
stem
the
compound
infects
of
Panama

disease
length
variety, Cavendish,
plantations
Synthetic
tropics. A
and
3
the
in
1950s. Another
division
banana
disease
disease
a
axillary
ground.
energy
the
not
are
meristematic
The
separate
stored
of
does
have
rhizome.
much
times
it
There
by
vegetatively
mitosis. They
grow
of
hot,
undifferentiated
point
which
system
adventitious
Leaves
kinetin
is
used
in
tissue
culture
to
stimulate
cell
division.
so
Module
Articial
Cuttings
are
plant
taken
that
from
has
plants
good
by
removing
features
that
are
stems,
worth
root
or
leaves
propagating.
from
This
done
by
a
stimulate
a
leaf

across
e.g.

at
the
a
point
side
the
where
shoot
Joseph’s
across
coat,
root,
cuttings
suitable
roots
soil
grow
stimulate
just
it
below
Coleus,
e.g.
meets
the
the
and
point
sugar
breadfruit,
stem,
e.g.
where
cane,
African
a
leaf
Artocarrpus
the
may
or
be
dipped
compost
from
the
for
base
into
the
growing
of
the
NAA
all
cuttings
cutting
and
then
After
the
a
new
placed
while
plant
into
a
adventitious
can
once
differentiation
support
genes
they
which
Root
been
means
are
genetically
which
Plants
that
divided.

are
new
they
identical
This
is
have
are
seeds
do
grow)
of
easy
are
composed
have
to
the
parent
be
to
of
way
at
most
plants
genetically
are
of
plant
plants
two
grow
from
are
functions
of
that
lost
they
are
the
specialised
some
whole
the
main
same
and
of
a
all
of
the
and
the
plants from
cells
shows
this
is
not
are
be
for
triploid
reproduction:
establish

and
and
plants
have
which
gives
plants
are
helps
uniform
a
appearance
reliable
uniform
harvesting
supply
size
and
which
packing
uniform
disadvantage
pests
epidemic
cells
case.
5%
The
or
the
out
cells
can
removed
which
carry
condition.
propagation
which
bananas,
as
thorned
vegetative
to
during
kept
which
genotypes.
thorns
the
that
only
chimeras,
different
with
for
base
cultivated
157
.
propagated.
viable
clones
for
their


cells
genotype
structures
vegetative
not
cultivated
plants
the
suckers
only
can
of
blackberry
grow
the
sterile,
(many
varieties
produce
trees
advantages
not
are
shoots
naturally
plants
Some
thornless
Banana
therefore
There
of
the
propagation.
and
taken.
that
cuttings
from
growth,
page
thought
cells
needed
differentiated
have
shoot
on
altilis
and
cuttings.
7
Did you know?
rest. Growing
they
and
stem,
ofcinarum
itself.
Not
growth
violet
joins
Saccharum
to Question
Scientists
Stem
root
cutting:
refer

biology
can
cytokinins
be
Reproductive
Link
propagation
Auxins
parent
3
is
diseases
pest
or
that
for
genetically
which
disease
they
there
is
a
uniform
have
no
chance
crops
are
resistance.
that
all
at
If
risk
there
plants
with
of
is
bleach
solution
the
an
the
scalpel
identical
genotype
will
be
wiped
out.
explant
Micropropagation
Many
tissue
commercially
culture .
medium
or
on
important
Small
a
pieces
solid
of
plants
tissue
medium.
The
are
are
propagated
removed
media
using
and
contain
methods
cultured
sucrose
as
in
a
a
of
cells
liquid
source
into
of
in
explant
callus
grow
tissue –
undifferentiated
energy,
nutrients
so
the
plant
cells
can
make
all
the
biological
need
and
plant
hormones
to
regulate
the
type
of
growth.
At
can
are
Aseptic
of
of
culturing
stimulated
to
technique
plants.
This
implements;
precautions
the
is
used
involves
spores
such
number
differentiate
as
are
to
into
removed
cells
stems,
ensure
sterilising
wearing
of
that
the
by
increases,
roots
no
appropriate
but
at
using
the
air
clothing,
the
divided
end
into
many
to
plants
cells
leaves.
contaminants
media,
ltering
and
be
the
grow
beginning
tissue
molecules
that
they
sterile
and
ruin
staff
masks
the
stock
containers
can
and
and
take
gloves.
Summary questions
1
Suggest
than
by
the
reasons
why
some
plants
are
propagated
vegetatively
rather
seed.
Figure 1.2.1
2
Explain
why
plant
hormones
are
used
in
tissue
culture.
Tissue culture is used to
produce large numbers of plants with
commercially important features
147
1.3
Sexual
reproduction
Sexual
Learning outcomes
reproduction
meiosis
On
completion
should

be
able
explain
the
of
this
section,
you
fusion
term
Most
sexual
insect
structure
of
pollinated ower
detailed
and
the
an
owers
structure
of
an
a
and
the
anther
female
Each
the formation
of
and
and
embryo
cycle
spores
fusion
in
the
are
of
gametes.
production
more
of
complex
In
owering
spores
than
the
into
her maphrodite
is
the
as
male
they
part
have
of
both
the
male
ower
a
Figure
is
composed
Each
develop.
to
The
of
a
lament
transport
anther
are
pollen
stages
end
of
of
is
water
,
composed
diploid
mother
cells,
cells .
development
meiosis
mature
pollen
1.3.1
and
the
four
grain.
make
photomicrographs
owering
plants
on
the
and
ions,
of
which
If
you
you
cells
Follow
life
page
cycle
of
sure
an
anther.
sucrose
four
pollen
you
pollen
divide
by
meiosis
look
can
see
at
sections
form
the
cells
tetrads
in
the
each
production
of
insect
can
nd
and
look
at
prepared
of
some
the
drawings
different
insect
inspect
sacs.
cell
so
meiosis
I
meiosis
II
of
that
you
parts. Then
pollinated owers
them
carefully
with
a
lens.
tetrad
four
of
haploid
pollen
cells
secretion
of
pollen
walls
grains
separate
nuclear
division
(mitosis)
tube
generative
nucleus
nucleus
divides
pit
Figure 1.3.2
later
to
form
two
male
gametes
exine
Cross section of an anther
intine
showing release of mature pollen grains
from the four pollen sacs
148
to
is
contain
acids
to
pollen
form
anthers
stages
of
slides
(diploid)
pollinated owers
identify
hand
and
carpel
where
Figure 1.3.1
Pollen grain production in a pollen sac of an anther
of
which
pollen
81.
foc us
photos
by
female
amino
sacs
pollen
Look for
the
Filaments
and
of
mother
S tudy
and
and
Link
of
the
produced
pollen
at
sacs.
At
yourself
before
those
pollen
different
Remind
plants
145).
stamen
phloem
anthers.
grains,
grains
are
life
The
the
part.
stamen
xylem
the
ovule
describe
the
page
The
involves
plants
typical
grains

(see
structures.
the
describe
in
gametes.
Rhizopus
to:
reproduction

occurs
of
in flowering
or
meiosis.
develops
grains
in
Module
Pollen
outer
grains
wall,
There
are
divides
have
the
pits
by
a
thin
exine,
in
the
mitosis
to
inner
made
exine.
form
of
wall,
The
a
the
intine,
sporopollenin
haploid
generative
made
which
nucleus
nucleus
is
of
within
and
cellulose
tough
a
the
tube
and
and
a
thick
the
base
of
the
carpel
is
the
ovary,
which
is
swollen
to
ovules.
Each
ovule
is
attached
to
the
inside
of
the
pollen
Pollen
grain
nucleus
enclose
ovary
take
one
grains
soil,
so
water
and
nutrients.
The
integuments
enclose
the
that
nucellus
are
lake
or
depths
very
peat
it
is
resistant.
If
you
samples from
possible
to
tell
or
the
vegetation
has
changed
in
it
an
receives
biology
Did you know?
how
more
Reproductive
waterproof.
different
At
3
and
area
over
time. This
is
useful
in
a
archaeology.
diploid
embryo
haploid
nuclei.
mitosis
to
sac
Three
form
inside
the
nuclei
may
eight
embryo
fuse
S tudy
mother
of
these
haploid
sac
to
cell
that
form
a
that
divides
degenerate
nuclei.
you
can
diploid
in
meiosis
leaving
These
see
by
move
Figure
one
to
to
form
nucleus
occupy
1.3.3.
The
four
to
the
two
divide
by
positions
polar
nucleus.
foc us
Degenerate here means that the nuclei do not divide again, do not function and
probably break down. Degenerate is also used to describe the genetic code where
it means that there are more codes than needed for 20 amino acids (see page 67).
ovule
nucellus
stigma
integuments
4
haploid
cells
style
micropyle
meiosis
ovary
funicle
1
ovule
haploid
grows
embryo
embryo
stalk
sac
sac
3
of
mother
cell
to form
cell
degenerate
(2n)
ovule
divides
by
meiosis
carpel
(funicle)
to form
containing
4
haploid
cells
ovule
mitosis
3
antipodal
cells
embryo
2
8
polar
2
which
sac
at
nuclei,
nuclei
nuclei
stage
later fuse
stage
4
nuclei
stage
synergid
mitosis
ovum
Figure 1.3.3
(female
gamete)
mitosis
The development of the embryo sac in the carpel
Summary questions
1
Describe
mature
the
embryo
2
Explain the
3
Suggest
embryo
4
why
possible
that
occur
three
nuclei
mother
is
to
to
produce
a
mature
pollen
grain
and
in the owering
plant
life
a
sac.
advantages of
sac
Palynology
is
events
the
use
meiosis occurring
degenerate following
the
meiotic
division
cycle.
of
the
cell.
study
of
pollen
spores,
grains
to
including
show
pollen
how
grains.
vegetation
Suggest
has
how
changed
it
over
Figure 1.3.4
historical
time.
This shows an embryo sac
mother cell at the metaphase II stage of
meiosis
149
1.4
Pollination
Learning outcomes
Self-
and
Pollen
On
completion
of
this
section,
be
able
dene

the
pollination
between
self-
is
and
the
different
in
which
the
which
as
explain
in
ways
is
which owering
plants
from
anthers
is
pollen
known
sacs
as
when
the
anthers
dehiscence.
Pollen
break
grains
open.
are
sac
page
gamete
inside
164).
transfer
anthers
of
an
is
ovule.
The
rst
pollen
opening
transferred
the
Fertilisation
stage
grains
to
to
in
from
release
the
is
gamete,
internal
transfer
anther
pollen
female
the
to
is
as
is
in
pollination,
stigma.
directly
it
which
onto
This
the
may
be
stigma
in
as
self-pollination
promote
Self-pollination
stigma
how
as
male
in
cross-pollination
outline
the
(see
the
simple
happens

released
the
embryo
mammals
cross-pollination

of
to:
term
distinguish
are
opening
way

grains
you
The
should
cross-pollination
in
the
is
the
same
transfer
ower
or
of
in
pollen
from
another
the
ower
anther
on
the
of
a
same
ower
to
a
plant.
cross-pollination
occurs.
Flowers
grains
Many
of
are
the
groundnut,
transferred
owers
are
Arachis
directly
adapted
for
hypogoea ,
from
anthers
do
to
not
open
and
pollen
stigma.
cross-pollination
so
that
pollen
is
Did you know?
transferred
The
world’s
titan
arum,
which
smelliest ower
is
the
Cross-pollination
Amorphophallus titanum,
grows
in
Indonesia.
It
gives
one
plant
smell
of
sweat ies
rotting esh
as
to
to
a
is
owers
the
stigma
of
on
different
transfer
a
ower
of
plants
pollen
on
in
from
another
a
the
plant
specic
anther
of
the
way.
of
a
same
ower
on
species.
off
There
the
between
are
at
least
ve
agents
of
cross-pollination
as
shown
in
the
table.
attract
pollinators.
Agent of
pollination
Ways
in
which
an
example
is
adapted for
pollination
wind
maize,
Zea mays,
owers;
the
plant
promote
insect
to
separate
release
male
(tassels)
pollen
are
into
and female
at
the
the
air
top
of
to
dispersal
periwinkle,
owers
has
male owers
Catharanthus roseus,
with
pollination
nectar
by
at
the
butteries
base
that
has
–
long
narrow
adapted for
have
long
mouthparts
bird
(e.g.
hummingbird)
false
red
bird
cannot;
water
of
which
paradise owers,
a
these
seagrass,
into
is
the
colour
are
long,
Heliconia spp.,
can
see,
that
is
on
but
are
insects
tube-shaped owers
Thalassia testudinum,
water
to female owers
Figure 1.4.1
birds
releases
carried from
separate
pollen
male owers
plants
Many orchid species deceive
their pollinators by attracting them with
scent but not having nectar as a reward.
Others look like female insects, so males
come and mate with them!
150
bat
seabeans,
pungent
Mucuna spp.,
are
smelling owers
vines
to
that
attract
have
bats
large
Module
Insect
pollinated
owers
have
features
that
attract
insect
3
Reproductive
pollinators:
S tudy

scent

brightly

coloured
nectar
–
solution
provide
insects
visiting
ower
of
sugars
with
a
honey
guides
–
‘reward’
for
petals
lines
on
Find
some owers
directing
to
the
centre
pollen
structure
pollination.
not
are
of
insect
The
to
an
Orchids
offer
in
in
deception
the
by
are
a
insect
grains
The
deception.
form
of
Some
nectar
,
mimicking
to
source
of
food
for
are
pollinators
the
of
the
the
the
orchid
of
for
stigmas
mate
with
scent.
them
Male
insects
thereby
electron
are
attracted
transferring
to
here. Also nd
micrographs
plant
species
that
spiky
are
they
so
have
a
of
also
sticky
and
as
if
they
should
practise
insects
and
S tudy
sex
the
owers
emitting
and
foc us
an
attempt
your
knowledge
to
promote

Dioecy .
plant
avoid
of
has
produce
fruits.
Dichogamy .
reducing
Male
in
sexes
trees
uvifera ,
with
need
Self-pollination
Stamens
chances
protogyny
Coccoloba
separate
owers.
of
and
to
is
is
trees
be
the
page
is
the
ready
Bidens
period
anthers
to
of
accept
example
for
of
a
overlap
are
ripe
the
male
female
or
trees
to
do
not
open
at
the
Aristolochia
matures
and
same
species
accepts
time
so
Summary questions
show
pilosa
is
a
species
that
shows
pollen
before
protandry
the
Dene
the following
mature
them.
when
and
In
the
release
many
pollen
grains
dichogamous
anthers
are
open
before
species
releasing
the
there
to
allow
self-pollination
as
a
fail
Heterostyly
a
species.
as
the
is
the
Some
style
is
existence
plants
very
have
short;
of
plants
owers
other
with
with
plants
of
two
the
the
dioecy,
dichogamy
stigma
is
pollen
terms:
in
and
a
and
self-incompatibility
the
Distinguish
between
the
safe.
following

10
dioecious
either
2
stigmas
to
155.
pollination,
which
self-
8
impossible.
carpels
stigma
an
producing
nearby
cross-pollination.
which
open.
and
to Questions
cross-
1
anthers
meiosis
self-pollination.
Seagrape,
that
female

and
and
to
understanding
ways
stigmatic
do
pollen.
variety
of
they
on
pollination
that
some
surfaces.
petals.
incompatibility
Flowering
insect
insect
Others
female
listed
Apply
appropriate
are
the features
grains.
look
not.
the
so
often
pollen
do
on
anthers
and
owers
they
appearance
stages
adapted
sticky
hold
but
is
above
are
surfaces
projections
landing
owers
usually
pollen
body.
small
practise
food
the
insect’s
covered
pollinated
stigmas
self-pollinate,
stick
as
ower

The
–
of
some
the
that
and nd
the

petals
foc us
to
pollinated

biology
types
anthers
same
of
ower
above
species
within
the
pairs
of
terms:
pollination
and
anther
stigma;
self-
cross-pollination;
stigma
have
and
protandry
and
owers
protogyny.
with
anthers
insect
below
pollinators
transfer
pollen
the
pick
stigma
up
as
pollen
the
on
is
long.
This
different
style
parts
of
ensures
their
that
bodies
and
3
Describe
the
different
which owering
from
ways
plants
in
promote
cross-pollination.

owers
with
short

owers
with
long
styles
styles
to
to
owers
owers
with
with
long
short
styles
4
styles.
Explain
the
advantages
of
cross-
pollination.

Self-incompatibility.
pollen
grains
Plants
germinate
and
also
have
grow
on
genes
that
stigmatic
determine
surfaces.
whether
The
S
gene
5
has
multiple
alleles
(see
page
102).
If
a
pollen
grain
has
an
allele
Suggest
plants,
is
the
same
as
one
on
a
stigma
it
will
not
Male
sterility .
grains.
in
the
This
Some
can
nucleus
be
and
mutations
the
also
result
genes
of
in
result
in
but
the
mutations
in
failure
genes
mitochondria.
to
on
Plants
produce
allele
cannot
self-pollinate
so
The
stamens
have
to
be
breeders
make
use
of
male
sterility
by
of
plants
cannot
have
are
hybrids
between
existing
in
animals.
some
cabbage
pollen
due
produce functional
to
a
mutation
that
the
mitochondrial
activity
cross-pollinated.
breeding
maize
the
anthers.
Explain
why
varieties
mitochondria
that
rare
in
chromosomes
that
in
Plant
is
pollen
affects
mutant
dioecy
common
germinate.
6

why
that
are
required
to
varieties.
produce functional
7
Explain
sterility
the
to
pollen.
advantages
plant
of
male
breeders.
151
1.5
Pollination
Learning outcomes
to
After
Pollen
On
completion
of
this
seed formation
section,
pollination
grains
germinate.
should
be
able
describe
between
A
the
sequence
pollination
fertilisation
of
events
style
and
grows
towards
explain
stigmas.
tube
They
emerges
absorb
from
water
one
of
and
the
sucrose
pores
and
through
the
into
the
the
stigmatic
tissue
and
then
down
the
through
the
ovule.
and
in owering
plants
S tudy

on
pollen
to:
exine

land
you
signicance
of
foc us
double
fertilisation
Both

describe
a
a
the
zygote
plant,
b
an
development
into
a
mature
ovule
into
a
of
word
an
ovary
into
grains
and
‘germination’
seeds
that
you
are
are
said
to
using
germinate. Take
it
in
its
correct
care
when
you
use
the
sense.
embryo
seed,
and
The
c
pollen
pollen
tube
may
be
attracted
by
molecules
secreted
by
the
style
and/
a fruit.
or
ovule.
growth
Genes
This
of
in
proteins
embr yo
tube
to
cell
divides
the
the
is
tube
tube
needed
digest
by
an
a
example
is
the
to
are
by
of
During
give
two
in
which
the
direction
of
chemicals.
transcribed
growth
pathway.
mitosis
chemotropism
inuenced
nucleus
for
of
the
the
and
tube.
growth
haploid
translated
Enzymes
male
the
are
to
generative
gamete
provide
secreted
by
the
nucleus
nuclei.
The
tube
z ygote
enters
the
gamete
suspensor
ovum
the
micropyle
nuclei
nucleus
diploid
If
there
by
cell
is
male
from
more
different
of
form
the
one
nuclei
pollen
of
the
centre
is
ovule
same
the
the
the
the
nucleus
embryo
ovary
so
nuclei
and
sac
then
pollen
pollen
species
owers,
of
down
the
to
the
male
fuses
other
form
a
with
fuses
the
with
triploid
fertilisation
different
These
breaks
One
zygote
of
in
tube
sac.
double
grains.
the
of
embryo
from
pollinated
tip
diploid
This
than
plants
wind
the
the
in
nucleus.
gamete
different
case
to
enter
nucleus
endosper m
basal
can
and
grains
visited
blown
by
they
tubes
by
could
animal
the
will
which
wind.
all
in
be
fertilised
turn
have
form
come
pollinators
This
gives
from
or
,
in
the
the
embr yo
opportunity
for
much
genetic
variation
amongst
the
seeds
in
the
ovary.
Double fertilisation
The
suspensor
signicance
nucleus
divides
embryo.
before
In
the
of
by
some
double
mitosis
plants,
embryo
is
fertilisation
to
give
such
mature.
as
In
a
is
that
tissue
the
the
that
legumes,
cereals,
such
triploid
surrounds
the
as
endosperm
the
endosperm
maize,
developing
is
wheat
used
and
up
rice,
cotyledons
the
endosperm
grain.
The
sorghum
remains
signicance
and
millet,
after
for
the
us
provide
is
embryo
that
most
matures
these
of
the
crop
staple
and
remains
plants,
foods
and
in
rye,
the
in
the
oats,
human
diet.
plumule
After fertilisation
radicle
Once
fertilisation
embryo
and
the
with
obtains
the
occurred
cell
and
sucrose
This
is
The
shoot),
and
more
zygote
ions
divides
cells.
from
efcient
embryo
radicle
the
suspensor
the
than
continues
(embryonic
It
by
xylem
root)
divide
and
into
and
receiving
to
mitosis
grows
one
and
form
or
form
two
a
an
endosperm
phloem
water
to
to
the
through
nutrients
plumule
cotyledons.
cell
Legume
and
fat.
embryos
In
develop
cereals
the
two
single
cotyledons
cotyledon
is
The growth of the embryo of
Shepherd’s purse, Capsella
152
water
,
nucellus.
(embryonic
Figure 1.5.1
has
basal
endosperm.
from
basal
a
bursa-pastoris
absorbs
nutrients
from
the
endosperm.
that
swell
thin
and
with
is
not
starch,
a
store;
protein
it
Module
The
changes
internal
the
in
to
the
nucellus
the
is
fertilisation,
fruit.
The
dries
may
also
Seeds
testa.
they
The
out.
C.
Fruits
An
to
were
attached
As
a
seed
enlarges
ovule
now
retain
of
a
to
as
form
and
embryo
the
the
seed
ovary
accommodate
reabsorbs
water
eshy
development
the
and
fruit
is
is
so
that
orange;
Link
or
testa.
a
the
will
each
or
The
and
growing
eshy
biology
larger
,
becomes
become
an
coat
the
water
gets
Reproductive
175
you
to
on
some
pages
174
exercises
compare
and
development
of
section
includes
help
fertilisation
it
fruits
summary
that
internal
internal
in owering
plants
and
mammals.
dry.
are
the
the
ovule
integuments
may
released
inside
remains
to
the
mammals.
becomes
the
are
inside
in
the
example
from
the
is
pericarp
pericarp
away
are
it
and
bursa-pastoris
breaks
occur
as
ovule
or
bursa-pastoris
of
seed
the
wall
attachment
out.
dry
Capsella
a
fruit
The
seed
way
squashed
After
seeds.
embryo
same
3
of
rest
of
when
the
ovaries
of
the
the
fruit
ovule,
and
plant
it
have
and
breaks
leaves
two
one
a
scars
where
open.
scar
–
on
one
the
When
the
where
stigma
was
attached.
Genetic
Sexual
have
reproduction
been
where
the
variation
meiosis
that
If
a
the
gametes
because
in
owering
by
meiosis.
come
from
meiosis
produces
a
potentially
offspring
ower
fruit
has
will
the
will
been
show
same
plants
pollen
is
the
same
parent.
the
grain
most
In
nuclei
and
the
form
then
variation
it
as
is
cross-pollination
the
the
that
male
same
gamete
inbreeding.
this
that
some
the
female
is
pollen
be
not
of
for
likely
all
is
there
recessive
gametes
self-fertilisation
will
it
allele,
of
to
There
and
extreme
homozygous
little
plant.
fusion
leads
genes
recessive
self-pollinated
very
involves
Self-pollination
the
harmful
be
pollination
‘shufes’
the
Self-fertilisation
has
the
from
produced
that
nucleus.
plant
consequences of
a
high
If
a
probability
allele.
all
the
seeds
gametes
grains
in
originated
that
brought
Figure 1.5.2
the
male
nuclei
could
have
come
from
several
or
many
plants
Seeds of C.
bursa-pastoris
and
with fruits
therefore
All
the
alleles
within
seeds
for
each
have
some
or
fruit
the
all
there
same
of
could
genes,
those
be
but
genes.
a
very
there
wide
could
Remember
range
be
that
a
of
wide
when
genotypes.
range
we
of
looked
at
S tudy
the
we
genetics
crossed
of
plants,
two
we
varieties
only
such
considered
as
tall
and
one
gene
dwarf
with
pea
two
plants.
alleles
This
meant
Look
that
in
this
cross
all
the
pollen
grains
carry
a
single
allele.
But
if
many
different
genes
the
potential
for
variation
within
one
fruit
variation
is
in
large.
the
This
offspring
is
outbreeding
which
increases
the
tomatoes,
the
avocados
to
oranges,
see
that
limes
they
each
seeds
have
in
at
you
and
consider
foc us
when
amount
two
scars. They
are fruits.
of
generation.
Link
Plants
have
production
a
of
gene
that
controls
the
chlorophyll. Answer
Summary questions
Question
1
Explain
the
difference
between
pollination
effect
and fertilisation.
of
6
Describe
the
events
that
occur
in
the
ovule
between
pollination
and
page
inbreeding
expression
2
on
of
this
156
on
to
see
the
the
allele
in
the
seed
phenotype.
dispersal.
3
Explain
the
signicance
of
the
double fertilisation
that
occurs
in owering
plants.
4
State
S tudy
the functions
of
the following
structures
in
the
ovary
between
Before
pollination
and fertilisation:
integuments,
micropyle,
pollen
tube,
you
start
generative
Make
a
plants.
table
to
compare
Remember
5,
make
table
a
list
in
of
answer
the
nucleus.
features
5
your
tube
to Question
nucleus,
foc us
to
asexual
include
and
sexual
similarities
as
reproduction
well
as
in owering
differences.
to
to
include
compare.
Do
the features
not forget
as
the rst
column.
153
1.6
Plant
reproduction
The
Learning outcomes
tasks
and
knowledge
On
completion
should
be
able
of
this
section,
owering
you
sequence
the
reproduction
events
in
compare
with
this
in owering
do
plants
asexual
use
sexual
your
test
in
your
with
this
ability
sexual
section
to
will
compare
reproduction
help
you
sexual
in
organise
your
reproduction
in
humans.
a
table
chapter
some
to
show
and
the
research
144–45
to
the
different
ways
nd
in
out
reproduce
groups
which
how
they
the
of
organisms
reproduce.
species
described
Y
ou
will
mentioned
need
in
to
on
sexually.
reproduction
reproduction
Generation
to

and
plants
Make
sexual
pages

questions
to:
1

summary
knowledge
the
time
next.
The
(G)
is
dened
mean
as
the
generation
length
time
is
of
time
from
calculated
one
using
generation
the
following
and
formula:
understanding
describe
and
of
pollination
explain
to
the
t
__
G
adaptations
of
local
foc us
Don’t forget
that
mathematics
This
you
is
an
need
in
to
your
apply
mathematical
=
time
table
shows
the
rate
of
of
need
to
biology
a
topic
and
division
Bacterium
you
example
t
n
=
number
of
generations
n
The
S tudy
where
=
species.
of
some
species
of
bacteria.
Number of divisions
Generation
in
time/min
24
hours
use
course.
Streptococcus lactis
55
Escherichia coli
72
Staphylococcus aureus
48
Mycobacterium tuberculosis
18
where
your
knowledge.
2
Copy
each
A
and
typical
sucrose;
medium
amino
phosphate
an
3
auxin
Find
complete
bacterium
ions
and
out
these
a
in
for
acids;
and
the
table
by
calculating
the
generation
time
for
minutes.
tissue
culture
vitamins;
trace
contains
nitrate
quantities
of
ions,
iron
the
following
potassium
ions
and
components:
ions,
copper
ions;
cytokinin.
why
the
components
components
and
are
explain
necessary.
why
they
are
Make
a
table
required
by
to
the
show
plant
cells.
4
Find
out
how
pollinator(s)
their
Yucca,
Present
you
Crotalaria,
tuberosa ,
your
start
making
your
for Question
of
6,
make
asexual
reproduction. You
spider
diagram
Find
to
knowledge
154
pollinated,
adaptations
Aristolochia,
Bougainvillea ,
ndings
as
photomicrographs
or
a
and
list
of
the
sequence.
sexual
might
other
also
make
and
the
Y
ou
can
help
of
that
list
they
their
have
main
for
a
poster
Cocos
nucifera ,
Euphorbia
attracting
or
other
Melicocca
pulcherimma ,
form
of
bijuga ,
Ipomoea
presentation.
topic.
the
of
pollen
Annotate
photographs
formation
the
and
and
photographs
of
pollen
arrange
embryo
with
grains
and
them
in
sac
the
information
embryo
correct
about
meiosis
sacs.
a
use
these
photographs
and
notes
to
help
with
your
graphic
organise
this
Print
development
matching
organiser
the
are
table
formation.
features
describe
owers
foc us
5
Before
and
following
pollinators:
Ruellia
S tudy
the
them
together
.
your
6
Make
table
to
compare
reproduction
a
in
plants,
asexual
animals
reproduction
and
with
sexual
microorganisms.
revision
by
Module
This
7
is
Put
you
a
list
of
these
–
it
events
events
is
in
occur
the
during
correct
sexual
sequence
for
reproduction
a
plant
that
in
owering
shows
plants
protandry.
The
Letter
Event during
A
cell
B
ovum,
synergids
C
pollen
tube
D
two
E
male
F
pollinator
G
pollen
grain
ripens
H
pollen
tube
of
I
generative
J
tip
zygote forms
K
male
endosperm
L
pollen
ower
bud
pollen
insect
3
of
4
reproduction
opens
cell
pollinator
divides
by
meiosis
visits ower
grains form
cells
pollen
degenerate
nucleus
generative
pollen
and
sacs
dehiscence
embryo
sac
understand
plants
sexual
mother
pollen
and
(A
to
Reproductive
biology
X)
rst
one
has
been
done
for
A.
Event during
T
o
that
3
divides
tube
by
mitosis
nuclei form
anther
mother
cell
divides
by
meiosis
nucleus forms
some
animals.
of
the
Now
genetics
that
you
that
have
was
in
covered
Module
Module
2,
3
you
you
divides
nuclei
by
and
reaches
move
to
deposits
tube
to
M
cells form
N
micropyle
centre
with
of
O
embryo
sac
P
ovum
pollen
on
Q
stigma
R
is
S
divides
breaks
nucleus fuses
apply
times
antipodal
through
nucleus
pollen
needed
three
Letter
germinates
grows
grain
reproduction
mitosis
nucleus fuses
of
can
sexual
with
know
by
T
mitosis
U
open
polar
compatible
the
style
V
nuclei
with
something
knowledge
W
stigma
about
from
X
reproduction
this
module
in
to
genetics.
Self-incompatibility
present
The
in
table
the
is
pollen
shows
determined
mother
possible
by
multiple
alleles
at
the
S
locus.
Pollen
grains
express
one
of
the
two
alleles
cell.
pairings
between
plants
with
ve
different
genotypes.
A
minus
sign
indicates
that
no
1
fertilisations
are
possible.
In
the
others,
either
half
)
(
or
all
of
the
pollen
is
capable
of
germinating,
growing
2
pollen
tubes
and
fertilising
the
ovules.
1
8
Copy
and
complete
the
table
by
writing
‘
’
or
‘all’
where
appropriate.
2
Genotype of
male
parent
Genotype of female
s1s2
s1s2
parent
s1s3
s2s3
s2s4
–
s1s3
–
s2s3
–
s2s4
–
s3s4
9
Explain
10
Use
the
s3s4
–
why
some
results
in
pollen
your
grains
table
to
can
germinate
explain
the
and
fertilise
advantage
of
ovules,
but
others
cannot.
self-incompatibility.
155
1.7
Practice
Plant
1
a
With
reference
TWO
b
natural
Explain
Discuss
and
the
growing
Irish
named
areas
potatoes
asexual
describe
5
a
reproduction.
propagation
is
used
and
and
with
disadvantages
crops,
sweet
such
potatoes,
as
in
of
by vegetative
the
i
pollination
ii
ovule
and
iii
ovule
and female
that
Some
species,
Mexico,
have
pollinated
by
such
as
the following
and fertilisation;
iv
seed
ovary;
gamete;
and fruit.
Describe TWO
methods
to
ensure
that
cross-
reproduction.
Salvia roemeriana
some flowers
insect
between
are
pollination
2
differences
ginger,
b
produced
Explain
pairs:
horticulture.
advantages
large
questions:
reproduction
examples,
of
why vegetative
agriculture
c
to
methods
exam-style
that
pollinators
open
and
from
and
c
are
others
cross-
that
Suggest
occurs.
how
inbreeding
you
on
a
would
species
investigate
of
garden
the
effects
of
plant.
never
6
The
pickerelweed,
Pontederia cordata,
is
an
aquatic
open.
plant
a
Discuss
the
benefits
of
having
two
types
that
ponds
on
the
same
lives
and
tropics
but
has
including
been
originates from
introduced
the Caribbean.
It
throughout
has
the
brightly
coloured flowers.
b
Describe THREE
ways
in
such
which
insect
c
The
plants,
apart from flower
as
the
periwinkle,
on
the
of
colour,
collected from
was
of
C. roseus
is
the
continued for
the
crosses
the
table.
In
each
genotype
of
the
Cross
number
During
an
wild
two
albino
investigation
in
an
cell,
d
chromosomes
ovule
each
of
is
nucellar
16. State
the following
cells
as
have
and
cross-pollinated. This
generations. Among
seedlings
case
to
each
of
were
the
parental
appeared
as
researchers
some
reported
deduced
of
in
the
plants.
Genotype
Number of observed
plants
the
albino
cells
endosperm
integument
plants,
1
Aa
× AA
149
0
2
Aa
× Aa
70
22
3
Aa
× Aa
65
28
4
AA
109
0
cell.
such
internal
named
contribution
parent
zygote,
cell,
in flowering
described
the
percentage
female
cell,
why fertilisation
C. roseus,
For
in
after fertilisation:
antipodal
Explain
as
e
of
of
species
plants
green
number
edges
this
attract
pollinators.
diploid
water
seedlings
plant.
periwinkle, Catharanthus roseus,
Madagascar
shallow
lakes. Albino
been found.
The
in
of flower
in
c,
the
state
male
the
parent
nucleus following
and
× Aa
cross-
fertilisation.
a
3
a
Compare
structure
b
Outline
be
c
the
of
the
achieved
Explain
plant,
than
why
such
the
a
Make
a
a
mature
ways
in
of
the
as
which
seeds
a
pollen
grain
with
the
may
sac.
cross-pollination
may
a
show
natural
outbreeding
more variation
inbreeder,
such
drawing
of
a
cross
section
as
of
the
an
anther.
b
Describe
pollen
c
the
mother
changes
a flowering
production
156
pollen
cells
give
rise
to
grains.
Describe
of
how
of
plant
a
that
occur
in
the
ovule
between fertilisation
mature
seed.
the
Explain
c
genetic
why
with
it
is
these
Discuss THREE
researchers
the
and
results
diagrams
not
deduced
of
to
possible
each
help
to
pickerelweed
ways
between flowering
Arachis hypogoea
labelled
b
use
cross
natural
how
genotypes from
plants.
of
Zea mays,
of
a
embryo
in flowering
seeds
groundnut
4
structure
Explain
in
which
plants
is
the
cross.
your
carry
(You
answers.)
out
a
test
plants.
cross-fertilisation
promoted.
Module
7
Callus
tissue
is
undifferentiated
tissue
explants
culture
of
plant
medium. An
tissue
are
placed
investigation
was
into
into
the
effects
of
plant
callus
tissue
was
on
tobacco,
prepared from
Nicotiana tabacum,
and
is
media
containing
different
and
unlikely
cultured
that
there
plant
hormones,
the
auxin
concentrations
IAA
and
kinetin,
results
are
shown
topics from
the
exam,
other
but
modules.
you
should
are
many
connections
between
be
topics
Learning
about owering
plant
and
in
human
It
is
much
is
useful
easier
to
background
genetically
knowledge for
modify
cells
in
Module
tissue
below.
Concentration of
plant
in
of
culture
Treatment
about
a
2.
cytokinin. The
ask
happen
on
reproduction
two
8
to
leaves
Biology.
solid
6
callus
aware
of
foc us
carried
hormones
This
tissue. The
biology
a
Questions
out
Reproductive
which forms
S tudy
when
3
Effect of
hormones/
than
to
modify
advantage
of
tissue
section
genetically
whole
culture
plants,
which
so
you
this
can
is
an
learn
in
the
plant
on
modied
organisms.
hormones on
–3
mg dm
growth of
callus
9
a
Describe
the
changes
that
occur
to
the
carpel
of
a
tissue
flowering
IAA
kinetin
2.00
0.00
b
1
little or
no
in
c
2.00
0.02
growth of
different
The
0.20
increased
of
callus
both
by
no
10
differentiation
conditions
world’s
climates
that
0.50
growth of
5
0.00
0.20
little or
in
reproduction
be
successful
wild flowering
may
be
and
strategies
plants.
of
global
changing. Outline
climate
change for
self-pollinate.
The
diagram
flowering
shows
the
growth
plant Shepherd’s
pastoris. The fruits
2.00
can
growth
with
4
asexual
seed
consequences
plants
2.00
after fertilisation.
roots
the
3
how
reproduction
growth
2
Explain
plant
of
this
of
purse,
species
an
embryo
of
the
Capsella bursa-
are
non-fleshy
and
shoots
each
contains
several
seeds.
A
no
growth
B
a
State THREE
ensure valid
the
b
precautions
that
comparisons
can
should
be
be
made
taken
to
between
treatments.
Summarise
the
the
of
growth
C
effects
callus
of
of
the
plant
hormones
on
N. tabacum
D
c
Explain
be
how
used
to
small
quantities
produce
large
of
callus
numbers
of
tissue
can
plantlets
of
N. tabacum
d
Make THREE
described
8
Tissue
One
culture
plant
b
is
a
method
the
of
carrying
meristems from
Describe
of
the
investigation
Name
b
Explain
artificial
out
shoot
appearance
tissue
tips
of
propagation.
culture
and
cells
is
culture
to
c
them.
Suggest
the
structures
why
the
taken from
a
d
an
advantage
of
using
meristems
in
B, C
and
D.
plants,
described
as
Explain
how
and
such
of
embryos
in
C. bursa-pastoris,
is
internal.
the
developing
nutrients
Describe
the
as
develops.
a fruit
as
changes
it
embryo
receives
the
requires.
that
occur
in
the
ovary
wall
plant
11
a
Explain
the
differences
between
the following:
culture.
Outline TWO
advantages
disadvantages
ornamental
of
and
using
crop
i
protandry
and
Suggest
how
raising
technique
to
ii
self-incompatibility
iii
self-fertilisation
it
easy
to
and
male
sterility
produce
and
cross-fertilisation.
plants.
plants
in
tissue
genetically
occurs
in
the
life
cycle
of
culture
flowering
makes
protogyny
and TWO
this
Double fertilisation
d
labelled A,
development
flowering
energy
meristem.
tissue
c
a
as
above.
technique for
remove
a
criticisms
engineer
plants.
plants.
b
c
Make
a
labelled
diagram
of fertilisation.
Indicate
structures
will fuse
Explain
that
the
significance
of
on
a
carpel
your
together
of
at
the
diagram
time
the
at fertilisation.
double fertilisation.
157
3
Reproductive
2.
1
Female
biology
reproductive
In
Learning outcomes
common
internal
On
completion
should
be
able
of
this
section,
organs
to:
cycle

describe
the
structure
of
of
the
year
.
mammals
occurs
on
mammals
Unlike
The
is
other
cycle
known
average
once
we
of
as
a
have
internal
mammals
changes
the
human
that
oestrus
month
and
occurs
cycle.
is
fertilisation
In
known
females
in
the
the
are
fertile
reproductive
female
as
and
humans
this
menstr ual
the
cycle.
human female
other
development.
throughout
you
with
system
(The
word
menstrual
is
derived
from
a
Greek
word
for
moon
and
reproductive
the
Latin
word
for
month.)
The
female
system
is
coordinated
so
that
the
system
activities

state
the functions
of
the
uterus,
cervix
functions

produce

transfer
the

foc us
several
different
most
the
important
Organ
Structure
ovaries
pair
of
ovaries
outer
situated
germinal
cortex
oviducts
muscular tubes
(Fallopian
epithelium
tubes)
tissue
uterus
inner
a
site
the
gametes
gametes
for
(secondary
from
internal
months
–
lining
either
table
and
is
and
system
are
to:
the
oocytes)
ovaries
to
in
the
the
ovaries
site
of
fertilisation
in
of
development
the
gestation
of
the
period
embryo
between
and
then
foetus
fertilisation
and
hormones,
from
oestrogens
and
progesterone ,
which
are
cholesterol.
outlines
the
structure
and
functions
of
each
organ
labelled
in
2.1.1.
the
of
uterus
medulla
lined with
ciliated
– to
endometrium
blood
– feathery
uterus
–
rich
in
vessels
layer
uterus
vagina;
side
lead from mbriae
muscular
of
female
produced
epithelium
surrounding ovary
glands
from
reproductive
Functions
surrounding
neck
female
is
Figure
cervix
the
female
nine
secrete
The
outer
synchronised.
oestrogen
oestradiol.
with
of
female
steroids
hormones. The
are
birth

are
uter us
oviduct
provide
for
There
and
and
vagina.
S tudy
ovaries
ovaries,
The
oviducts,
of
is
that
consists

produces

secretes
oestrogens,
the
secondary

secretes
progesterone

transports

site

transports

endometrium

myometrium
oocytes
e.g.
secondary
oestradiol
oocytes
to
uterus
of fertilisation
embryo
is
to
site
uterus
of
development
contracts
during
of
embryo/foetus
birth
myometrium
separates
of
ring
of
uterus
muscle

secretes

cervix
mucus
appears
–
consistency
to
be
closed
changes
except
during
around
each
time
month
of
ovulation

circular
muscle
at
base
of
uterus
retains
contents
during
pregnancy

plug
of
antibacterial
mucus
during
pregnancy
reduces
infection
vagina
muscular
tube
with folded
inner
lining

muscle

epithelium

bacteria
(pH
vulva
158
external
genitalia
including
clitoris
and
labia
3.8

site
of

birth

many
relaxes
during
secretes
produce
–
4.5)
to
birth
acid
prevent
of
cervix
dilates
mucus
lactic
deposition
so
to
provide
growth
semen
of
during
acidic
other
environment
microorganisms
intercourse
canal
sensory
receptors for
arousal
during
intercourse
Module
3
Reproductive
endometrium
oviduct
S tudy
This
foc us
photomicrograph
ovary
funnel
biology
at
one
stage
cycle.
Search for
other
stages,
of
shows
the
images
the
menstrual
that
show
of
or
look for
diagrams
oviduct
that
show
all
the
stages.
uterus
ovary
myometrium
cervical
canal
cervix
vagina
vulva
Figure 2.1.1
The human female reproductive system. The structures labelled are primary
sexual characteristics and their functions are described in the table.
Y
ou
may
through
in
slides
cycle.
have
the
with
Y
ou
to
make
ovary
of
a
a
diagrams
will
not
After
ovulation
form
the
see
the
drawing
small
as
they
these
cells
of
from
a
mammal.
often
when
the
prepared
Beware
show
you
all
look
Graafian
of
slide
the
at
a
follicle
of
a
section
comparing
stages
of
what
the
you
see
ovarian
slide.
that
remain
in
the
ovary
Figure 2.1.2
corpus
A photomicrograph of an
luteum.
ovary showing a Graafian follicle
The
table
shows
the
functions
of
the
regions
of
the
ovary.
Summary questions
Region
Functions
1
Outline
in
germinal

cells
lining
outside
of
ovary
divide
by
mitosis
(before
the
the
to form
cortex

outer
oogonia
region
surrounded
contains
by follicle

secondary
oocyte
primary follicles
develops
within

outer
layer
is
the
theca
that
ovary,
2
and
Find
diagram
a
fluid lled
antrum
creates
uterus,
the
vagina.
or
changes
diagrams
that
that
occur
the Graaan follicle
secretes
the
pressure
ovary
during
the
oestradiol
ovarian

oviduct,
cervix
within
follicle
the following
cells
show
Graaan
of
reproductive
birth)
system:
epithelium
roles
human
to
burst follicle
cycle.
Make
a
series
of
at
simple
diagrams
of
the
ovary
ovulation
to
show
during
stroma

forms
theca
of
a
contains
connective
tissue
and
blood



occur
show
the
diagrams
development
a follicle,
ovulation
and
the
vessels:
supply
nutrients
to
developing follicles
oestrogen
and
take
oestradiol from
away
progesterone
progesterone from
corpus
secretes
and
and
oestradiol
development
and
degeneration
of
luteum.
cholesterol for
the
corpus
synthesis
theca
and
oestradiol
and
3
luteum
Explain
what
happens
development
4
corpus
cycle. Your
that
vessels
of
blood
changes
maturing follicles
should

the
Describe
the
of
in
the
the follicle.
structure
of:
i
an
progesterone
ovary;
ii
the
uterus. Outline
the
luteum
functions
in
The
primary
follicles
complement
of
reproductive
life.
how
many
develop
follicles
there
If
you
are
that
before
will
answer
and
what
birth,
last
a
at
woman
Question
happens
so
10
to
the
on
the
birth
there
length
page
177
number
is
of
each
the
different
tissues
organ.
full
5
her
you
over
a
of
will
time.
see
Explain
why
synchronise
ovary
with
it
is
the
important
changes
changes
in
in
the
to
the
uterus.
159
2.2
Male
reproductive
The
Learning outcomes

On
completion
of
this
section,
functions
produce
of
very
be
able
describe
the
structure
of
large

state
male
reproductive
the functions
epididymis,
prostate
vas
gland,
of
the
system
testes,
deferens,
seminal
cells
produce
numbers
of
male
system
are
gametes
to:
(singular
spermatozoon),
but
which
which
are
we
known
will
call
as
sperm
for
or
short
a
liquid
medium,
semen,
for
the
delivery
of
sperm
into
the
vagina

secrete
from
the
male
hormone,
testosterone,
which
is
a
steroid
produced
cholesterol.
vesicles,
The
penis,
reproductive
the

human
male
to:
sperm

the
you
spermatozoa
should
system
production
of
sperm
cells
does
not
involve
the
synchronisation
of
urethra.
two
organs
process
in
as
the
throughout
The
table
in
testes
female.
so
that
reproductive
outlines
reproductive
the
Instead
there
millions
is
upon
the
control
millions
of
of
the
sperm
production
are
available
life.
structure
and
functions
of
the
organs
of
the
male
system.
Organ
Functions
testis
(plural
the
testes)
epididymis

produces

secretes

collects
fluid
scrotum
to
the
male
sperm from
stores
sperm

site
maturation

sac
containing
cavity
inside
seminiferous
concentrate

of
gametes
seminiferous tubules
testosterone
where
of
the
tubules
and
reabsorbs
them
sperm
testes
below
temperature
is
the
2–3 °C
abdominal
cooler
than
body
temperature
vas
deferens

muscular
tube
that
moves
sperm
peristalsis
by
during
intercourse
Cowper’s

gland
secretes fluid
urethra
prostate

gland
contributes
that
seminal

activate
secretes
lubricates,
and
during
semen
seminal fluid
that
secretes fructose

seminal fluid
protect
and
neutralises
secreting
mucus
and
chemicals
is
as
part
surround
to
provide
alkaline
to
of
the
semen
that
surface
energy for
neutralise
of
contains
sperm
motility
contents
of
of
sperm
vagina
sperm
urethra

contractile
glans

lls

inserted

sensory
with
by
cleans
ejaculation
sperm

to
160
to
glycoproteins
vesicle
(penis)
that
before
tube
blood
into
that
to
become
vagina
receptors
moves
at
during
the
semen
through
the
penis
erect
intercourse
tip for
arousal
during
intercourse
Module
pubic
3
Reproductive
biology
bladder
bone
urethra
seminal
vesicle
shaft
S tudy
foc us
rectum
Search for
photomicrographs,
glans
electron
prostate
gland
foreskin
of
micrographs
seminiferous
different
stages
and
tubules
of
drawings
to
see
the
spermatogenesis
anus
urethral
epididymis
opening
Cowper’s
scrotum
testis
vas
(testicle)
Figure 2.2.1
and
the
you
with Question
Sertoli
cells. These
will
help
2.
gland
deferens
(sperm
duct)
The human male reproductive system. The functions of the primary sexual
characteristics are described in the table.
Y
ou
may
through
The
have
the
table
to
make
testis
shows
of
the
a
a
drawing
small
from
a
prepared
slide
of
a
section
mammal.
functions
of
the
regions
that
are
in
the
testis.
Figure 2.2.2
Region
Functions
tunica

outer
A photomicrograph of a
testis showing seminiferous tubules
layer
of
connective
tissue
Summary questions
albuginea
1
seminiferous

site
of
sperm
Outline
in
tubules
of
the

site
meiosis
of

differentiation
of
diploid
cells
to form
haploid
the
human
haploid
cells
to form
the following
testis,
connect
together
to form
a
epididymis,
sperm
scrotum,
tubules
of
reproductive
cells
system:

roles
production
duct
into
vas
deferens,
seminal
the
vesicle,
prostate
gland,
urethra
epididymis
and
germinal

(lining
cells
divide
puberty
epithelium
by
mitosis
throughout
to form
spermatogonia
reproductive
– from
2
life
Make
of
of
penis.
a
a
drawing
showing
seminiferous
cell,
tubules)
interstitial
cells

secrete
of
seminiferous
a
sector
tubule
the following:
spermatogonia,
Sertoli
primary
spermatocytes,
secondary
spermatocytes,
spermatids
and
testosterone
spermatozoa.
blood
vessels

provide
other

cholesterol for
nutrients for
remove
testosterone
sperm
testosterone
to
synthesis
3
and
production
distribute
around
the
body
Suggest
the
of
the
into
the
cells
testes
do
are
scrotum
the
heat
not
held
ow
scrotum
loss
develop
within
to
from
close
blood
the
properly
the
at
body
scrotum.
together
owing
so
heat
back
temperature
Blood
vessels
transfers
into
the
which
owing
from
in
blood
abdomen.
This
is
why
and
out
owing
reduces
4
nutrients
the
sperm
Explain
think
Sperm
the
required for
cells.
each
Explain
nutrient
why
and
temperature
kept
several
of
that
are
production
why
is
how
the
you
required.
the
testes
degrees
of
is
below
body
temperature.
scrotum.
161
2.3
Gametogenesis
Gametogenesis
Learning outcomes
humans,
On
completion
of
this
section,
be
able
dene
the
terms
spermatogenesis
the
human
is
to
describe
gametogenesis,
number
and
and
oogenesis
84
does
we
the
process
spermatogenesis
to
to

the
process
produce
between
occurs
a
of
the
oogenesis
the
cycle
that
gametes
each
involves
are
are
produced.
In
meiosis.
produced
increase
generation
when
concerned
of
is
by
diploid
gametes
with
production
division
in
the
oocytes
ovum.
the
oocyte
give
differentiate
difference
secondary
to
The
as
well.
the
fuse
details
meiosis
human
and
at
of
gametes
the
and
are
haploid.
chromosome
fertilisation.
the
nuclear
we
Sper matogenesis
seminiferous
and
four
into
haploid
mature
nucleus
cytoplasm
eventually
nucleus

this
gametes
are
On
pages
division.
concerned
82
When
is
the
with
production
of
the
sperm
produce
secondary
understand
an
which
tubules.
Here
the
cytoplasm
divides
sperm
equally
discuss
by
of
that

not
were
cytoplasmic
mature
vertebrates,
life
ensure
considering

all
process
to:
This

in
the
you
In
should
as
is
and
very
sperm
divides
divides
become
cells
in
all
little
ovum
the
cells.
the
unequally.
the
of
size.
Oogenesis
same
This
and
same
way
as
results
three
tiny
is
in
in
the
cells
then
production
of
spermatogenesis,
one
cells
These
large
that
cell
each
that
an
but
may
contains
a
cytoplasm.
ovum
explain
are
how
adapted
the
to
human
gametes
spermatogonium
oogonium
their functions.
2n
division
2n
2n
by
Link
division
mitosis
by
2n
When
answering Question
3
2n
2n
mitosis
2n
make
cell
2n
sure
you
include
similarities
division
and
2n
2n
growth
fertilisation
nuclear
2n
in
differences
in
stimulates
primary
cytoplasmic
meiosis
division.
primary
II
oocyte
2n
spermatocyte
to
occur
meiosis
I
meiosis
I
secondary
secondary
n
first
oocyte
polar
n
body
meiosis
meiosis
spermatocytes
II
II
n
second
polar
n
n
n
spermatids
body
ovum
Figure 2.3.1
Oogenesis. Note
metamorphosis
the unequal division of
sperm
cytoplasm.
Figure 2.3.2
cells
Spermatogenesis. Note the equal
division of the cytoplasm to give four haploid sperm
cells. One sperm cell is enlarged to show its structure.
Spermatogenesis
about
three
About
begins
three
Both
The

cells
show
functions
deliver
a
the
of
principle
the
haploid
sperm
of
are
nucleus,
structure
a
related
the
to
to
at
of
to
the
female
a
girl,
set
of
restore

increase

stimulate

determine
162
the
diploid
genetic
is
the
not
in
from
a
process
the
testis
each
completed
and
takes
spermatogonium.
day.
until
half
Oogenesis
way
functions
of
an
oocyte
are
to:
paternal
provide
a
haploid
nucleus
with
a
set
of
gamete
chromosomes
number

increase

provide
genetic
variation
variation
meiosis
the
completed
sperm
start
but
maternal

is
function.
The
a
It
mature
cycle.

chromosomes,
puberty.
produce
spermatogonia
birth
menstrual
to:
with
million
before
through
begins
months
II
in
gender
the
of
secondary
the
next
oocyte
generation.
energy
supply
for
developing
embryo.
Module
Feature
Human
linear
length
dimension
overall
structure
head
sperm
=
nucleus
haploid
and
cell
membrane
using
(23)
–
very
–
nucleus),
to
mid
piece
movement
reduce
highly
the
condensed
and
oocyte
reduce
of
to
the
some
DNA
cell
very
haploid
biology
140 µm
and follicle
of flagellum
mass
=
Reproductive
secondary oocyte
spherical
mitochondria), flagellum
complementary
pellucida
little
and
contains
to
glycoproteins
cytoplasm
and
lashing
histones
zona
width
(acrosome
(axial lament
swims
Human
60 µm
piece
motility
cell
3
surrounded
by
zona
pellucida
cells
limited
motility
(23)
sperm.
proteins
on
microvilli
to
absorb
nutrients;
membrane
size
contains
organelles
such
as
RER,
SER, Golgi,
mitochondria
energy
store
very
little
from
acrosome
present
and
mitochondria
most
–
energy
provide
one
contains
spirally
enzymes,
digesting
around
energy for
below
flagellum
provided
by fructose
lipid
droplets
in
cytoplasm
vesicle
proteases for
arranged
centriole
–
seminal
e.g.
hyaluronidase
pathway
to
absent
oocyte
axial lament,
to
many
swimming
nucleus
– forms
and forms
mitochondria
development
the
centrioles
microtubules
of
of
none
–
to
provide
energy for
after fertilisation
centrioles
breakdown
during
oogenesis
zygote
Secondary oocyte
S tudy
The
oocyte
is
moved
does
not
with
motility.
have
energy
for
energy
stores
any
cytoplasm.
oviduct
within
cell
comes
the
all
Secondary
the
secondary
from
oocyte
also
needs
lipids
cell
and
proteins
membranes
that
form.
for
These
endometrium
to
the
make
many
sustain
and
the
absorbs
oocyte
oocyte
or
as
ovum? The
it
the
completion
of
the
tiny
polar
second
has
meiosis
not
cell
that
completed
II followed
body
and
the
Cell
surface
the
released from
meiosis.
an
ovum. The
also
forms
ovum
even
though
it
has
the
sperm
until
from
it
has
the
implanted
mother ’s
Cortical
granules
are
has
pronucleus
inside
in

Smooth
formed
released
proteins
to
absorb
lysosomes
at
endoplasmic
after
that
bind
to
proteins
on
Dene
the
terms
nutrients
from
the
made
by
the
Golgi
follicle
body
and
Rough
fertilisation
Explain
the
role
reticulum
to
make
lipids
for
new
3
membrane
Make
a
table
oogenesis
reticulum
to
make
proteins
required
Mitochondria
Lipid
using

First
provide
are
an
mRNA
produced
by
transcription
body
is
energy
for
processes
that
occur
after
well
a
as
Make
of
fertilisation.
a
energy
contains
a
one
very
to
of

Zona
again
by
the
small
pellucida
meiosis
is
a
include
Follicle
cells
form
large,
sperm
labelled
cell
and
diagrams
a
oocyte.
haploid
nuclei
formed
during
meiosis
Explain
quantity
of
cytoplasm.
It
how
human
sperm
I
secondary
oocytes
are
sometimes
their functions.
II.
region
the
similarities
differences.
of
glycoprotein
secreted
by
follicle
cells.
5
Explain
how
provides for

compare
spermatogenesis.
adapted for
divides
humans.
reserve.
and
which
in
before
b
polar
in
to
and
secondary
droplets
meiosis
immediately
4

of
fertilisation.
ovulation.

oogenesis
contain
as
after
and
cells.
fertilisation.
endoplasmic
gametogenesis,
sperm
Remember

called
it.
Summary question
the
gametogenesis
substances
to form
is
blood.
2

a
cells
embryo
microvilli
cell
is
stimulates
cytokinesis
spermatogenesis
cells;
ovary
Fertilisation
unequal
larger
the
new
new
nutrients
membrane
by
much
1

is
supplies
an
of
foc us
so
involved
fertilisation
division
The
the
structures
After
cell
along
corona
gametogenesis
genetic
variation
radiata.
amongst
the
next
generation.
163
2.4
Fertilisation
The
Learning outcomes
On
completion
should
be
able
of
this
and
section,
you
Graafian
of
with
release
the
occurs

state
where fertilisation
describe
the
process
of
the
the
about
swells
liquid
of
and
inside
the
oocyte
the
development
increases
oocyte
and
time
protrudes
and
follicle
of
and
some
cells
ovulation
from
this
the
side
causes
surrounding
is
ovulation.
then
there
is
a
of
the
the
follicle
follicle
If
ovary.
sexual
chance
to
cells.
The
burst
This
intercourse
that
fertilisation
occurs
will

follicle
pressure
release
to:
early
of
occur
.
releases
This
an
period
oocyte
of
time
during
is
each
the
fertile
menstrual
period .
Usually
one
ovary
cycle.
fertilisation
During

describe
the
early
The
of
the
stimulation
state
where
implantation
occurs
each
seminal
sperm

of
the
male
the
penis
inserts
his
results
in
penis
into
the
contraction
of
woman’s
the
vas
vagina.
deferens
embryo
from

intercourse
development
explain
the
process
testis
vesicle
to
form
so
sperm
and
the
semen.
are
moved
prostate
By
by
gland
further
peristalsis
release
to
uids
contractions
the
the
urethra.
that
mix
semen
is
The
with
the
moved
along
of
the
urethra,
through
the
penis
and
into
the
vagina.
implantation
The

explain
the
biological
vagina
tends
of
is
a
hostile
environment
for
sperm.
The
pH
is
low
and
this
principles
to
kill
sperm.
The
semen
coagulates
immediately
after
ejaculation
contraception.
and
then
together
liquefies
through
oviduct
help
ovarian
end
the
of
5
to
the
20
sperm
an
minutes
cervix.
on
their
oviduct.
later
.
They
Contractions
way
During
of
towards
the
collect
the
fertile
as
cervix,
the
site
period
a
of
the
mass
uterus
and
move
and
fertilisation
cervical
at
the
mucus
Did you know?
forms
Oocytes
survive for
about
channels
after
survive for
ovulation;
up
to
48
sperm
hours
cells
cells
through
after
oviduct
ejaculation.
hours
to
of
a
produce
day. One
over
100
ejaculation
million
sperm
to
300
million
sperm
ions
occur
sperm
to
fertilise
an
capacitation .
to
the
that
the
swim
through.
the
surface
removal
The
cell
increase
of
oocyte
As
of
the
they
the
pass
they
sperm.
also
motility
This
help
been
the
takes
from
become
and
have
through
glycoproteins
membranes
their
until
the
more
the
uterus
about
and
seven
outer
permeable
release
of
acrosome.
enter
Sperm
the
cells
oviducts
cluster
and
around
some
the
will
enter
the
oviduct
with
an
oocyte.
Fertilisation
contact
with
follicle
cells,
sperm
cells
are
stimulated
to
release
the
sperm. All
enzymes
those
of
contains
On
150
of
sperm.
from
sperm
oocyte.
able
involves
the
calcium
Some
not
process
changes
enzymes
Did you know?
are
the
and
surface
Men
groups
12–24
Sperm
hours
which
to fertilise
in
the
acrosomes.
This
is
known
as
the
acrosome
reaction .
one female
The
acrosome
swells
and
enzymes
are
released.
These
enzymes
digest
a
gamete!
pathway
oocyte.
two
digests
cells
cytoplasm.
cortical
make
which
the
fuse
This
follicle
is
it
the
The
through
the
digests
proteins
and
cells
whole
cell
impenetrable
entry
of
the
any
cell
zona
sperm
of
the
surface
to
the
triggers
contents
the
to
hyaluronic
in
immediately
reaction.
exocytosis
and
the
Hyaluronidase
protease
the
through
other
more
surface
acid
between
pellucida.
cell
is
to
This
lift
of
the
cells
and
membranes
into
the
the
oocyte
vesicles
membrane
sperm.
in
follicle
The
taken
changes
cortical
membrane
are
the
oocyte
with
the
released
zona
prevents
of
by
pellucida
polysper my
sperm.
Did you know?
Fertilisation
Sperm
by
mitochondria
proteins
the
in
the
embryo for
consequence
embryo
oocyte.
are
are
targeted
cytoplasm
of
destruction. As
all
mitochondria
derived from
The
the
a
in
those
oocyte
second
in
the
becoming
nuclear
The
less
of
the
the
final
divides
body
(see
nucleus
tightly
membranes
chromosomes
mitosis
164
polar
pronucleus.
the
triggers
nucleus
from
the
assemble
new
page
coiled.
of
division
and
the
meiosis
the
The
sperm
forms
pronuclei
the
cell
of
of
162).
This
two
on
diploid
one
the
in
male
plate
zygote.
secondary
is
extruded
nucleus
enlarges
break
the
nuclei
other
the
equatorial
–
new
with
the
the
and
form
female
chromatin
pronucleus .
down
at
is
oocyte.
to
The
the
metaphase
of
the
first
Module
The
zygote
nuclei
form
divides
divide
a
four-celled
hollow
ball
Further
into
again
of
by
embryo.
cells,
growth
two
cells
mitosis
This
known
occurs
as
with
to
and
a
form
the
two -celled
cells
continues
blastula.
the
a
two
until
Each
formation
embryo.
divide
the
cell
by
embryo
is
The
two
cytokinesis
called
an
inner
into
the
the
cell
mass
embryo
foetus,
that
and
grows
then

The
a
blastomere.
is
of:
an
trophoblast
detected
before
into
outer
layer
trophoblast
and
of
cells
that
forming
later
the
forms
in
to
nine
days
endometrium.
of
the
when
after
The
of
ovulation
cells
of
the
into
nutrients,
into
the
blastocyst
trophoblast
embeds
form
into
the
extensions
lining
from
of
the
endometrium
to
increase
the
foc us
the
the
surface
methods
described
small
water
blood
and
oxygen.
spaces
or
These
lacunae
are
in
trophoblastic
the
contraception
the
literally
summarised
in
the
Type of
means
of
preventing
oocytes
by
conception.
sperm.
The
other
prevent
methods
villi
Contraception
fertilisation
are
that
prevent
an
endometrium.
such
preventing
here
area
embryo
Contraception
even
the
of
protrude
–
menstruation
placenta.
blastocyst
absorption
which
tests
which
occur.
fertilisation. There
for
hCG
a
The
surface
secretes
pregnancy
time
S tudy
Six
biology
Did you know?
should

Reproductive
to
becomes
a
3
This
biological
as
implanting
the
in
the
uterus,
‘morning-after
pill’
and
coil.
involves
principles
are
table.
Biological
principle
Method
Efficiency*
contraception
Sterilisation
vasectomy
no
sperm
in
semen
each
vas
sperm
tubal
ligation
no
oocyte
in
oviduct
deferens
cannot
oviducts
cannot
are
pass
is
cut
and
pass from
cut
and
along
tied
testis
tied
so
so
to
0
urethra
oocytes
0
oviducts
Barrier
condom
(sheath)
sperm
do
not
vagina during
enter
condom
intercourse
entry
femidom
femidom
entry
diaphragm/cap
sperm
cervix
Contraceptive
no
do
not
during
enter
Number
prevent
the
by
of
pregnancies
pills
ovulation.
combined
negative
cycle

is
diaphragm
ovulation
the
surge
per
are
pill,
reduce
are
which
to
penis
ovulation
chances
before
into
vagina
before
is
placed
over
entry
to
pill
pills
women
from
per
types
contains
inhibit
that
(also
contain
oestrogens
of
one
to
or
both
prevent
and
contraceptive
oestrogen
secretion
known
causes
sperm
ovarian
0–2
ovulation
of
and
progestins
progestins;
GnRH,
FSH
to
pill:
and
these
the
act
Summary questions
mid
enter
a
as
the
‘mini
thickening
the
pill’);
of
this
cervical
pills
taken
to
are
taken
allow
for
20
days
menstruation
and
to
then
may
mucus
skin
hormones
and
may
are
also
also
be
terms:
implantation,
and
sterilisation.
uterus.
for
five
days
no
hormones
Explain
cell
are
what
during
happens
to
a
sperm
capacitation.
occur
.
delivered
injected
the following
contraception
to
3
The
Dene
fertilisation,
2
The
3–15
year
synthetic
several
also
3
cervix
1
but
3
penis
LH
progestin- only
prevent
made
There
feedback
of
100
over
placed
the
hormones
Contraceptive

of
placed
vagina
intercourse
pills
*
is
into
as
into
a
skin
muscle
patch,
for
an
slow
implant
under
the
Describe
the
events
that
occur
at
fertilisation.
release.
165
2.5
Internal
development
The
Learning outcomes
zygote
moves
On
completion
should

be
able
describe
of
this
section,
structure
of
along
the
endometrium.
you
to:
the
divides
some
of
these
born.
These
many
oviduct
The
times
into
embryo
form
tissues
to
the
form
uterus.
continues
that
extra-embryonic
a
will
to
not
tissues
multicellular
This
implants
divide
be
form
embryo
to
part
the
into
produce
of
the
it
the
new
baby
trophoblast
as
cells
when
at
the
it
and
is
start
of
the
pregnancy
and
later
form
part
of
the
placenta.
placenta
The

explain
the functions
of
extra-embryonic
tissues
develop
into
the
placenta
and
the
amnion.
the
Sometimes
they
are
called
extra-embryonic
membranes,
but
do
not
think
placenta
they

describe
the functions
of
are
cell
membranes,
they
are
layers
of
cells.
the
amnion.
The
The
placenta
placenta
tissue.
S tudy
foc us
The
sinuses
are
chorion
The developing
human
is
known
as
can
be
until
such time
seen. At the
as the organs
point when
it
and
is
recognisably
one
as
formed
of
in
the
from
blood
origin,
in
all
foetal
the
the
other
extra-embryonic
tissue
sinuses
and
and
tissues
tissues
and
from
the
are
maternal
cells
lining
foetal.
this
grows
these
The
of
chorionic
substances
between
villi
which
maternal
increase
and
foetal
the
surface
blood
area
to
form
for
the
exchange
systems.
has
human
it
blood
ows
into
the
placenta
from
the
uterine
artery .
This
is
is
oxygenated
known
organ
maternal
folded
Maternal
organs
an
an
highly
embryo
is
is
endometrium,
blood
rich
in
nutrients.
The
blood
ows
into
blood
‘lakes’
or
a foetus.
sinuses
which
placenta
in
bathe
the
the
uterine
villi.
Deoxygenated
blood
ows
away
from
the
vein
Link
Foetal
blood
The
placenta
is
an
organ, for
blood
to
look
back
to
page
answer Question
1
the
heart
arteries
along
branch
the
to
aorta
take
into
this
arteries
which
deoxygenated
carry
blood
the
umbilical
in
the
villi
cord
and
to
the
placenta.
returns
as
The
blood
ows
oxygenated
blood
in
a
through
vein
that
ows
opposite.
through
a
small
sending
oxygenated
from
Here
34,
capillaries
then
ows
legs.
more
through
information
the
the
umbilical
volume
all
the
of
cord
blood
blood
and
ows
from
the
then
returns
through
right
the
blood
foetal
ventricle
as
to
the
lungs
it
will
foetal
as
there
not
be
heart.
is
no
Only
point
oxygenated.
blood
The
foetus
mother
.
has
a
Without
different
genotype
a
separating
barrier
from
the
the
two,
amniotic fluid
the
mother ’s
immune
system
would
reject
the
placenta
foetus.
many
The
pathogens
Maternal
blood
blood
pressure.
foetal
blood
Pathogens,
uterus
placenta
worms,
the
are
and
in
If
the
too
chorionic
as
barrier
uterine
to
but
blood
artery
entered
they
to
cells,
proteins.
the
would
bacteria,
large
villi,
a
some
this
vessels
such
is
some
a
high
burst.
some
cross
has
delicate
the
viruses
and
epithelium
viruses
are
able
of
to
amnion
cross.
umbilical
Many
antibodies
that
circulate
maternal
deoxygenated
cannot
blood
cross.
If
are
very
they
did
large
molecules
likely
a
cross
some
that
would
to
do
serious
cells.
There
cross
the
are
damage
some
placenta
to
to
smaller
give
the
foetal
red
antibodies
foetus
be
to
vein
umbilical
arteries
The structure of the placenta showing: a detail of the
placental villi; b the umbilical cord with its three blood vessels; c a cross
section of the umbilical cord
diseases
that
the
mother
has
blood
that
immunity
c
umbilical
166
the
b
blood
Figure 2.5.1
in
cord
had.
Module
Exchange of
3
Reproductive
gases
S tudy
Foetal
and
in
red
two
the
blood
cells
γ-globins.
maternal
contain
This
red
a
binds
blood
form
of
oxygen
cells,
so
haemoglobin
more
readily
encouraging
with
than
the
two
the
haemoglobin
diffusion
the
placenta,
blood.
Carbon
down
the
concentration
gradient
into
of
the
foc us
α-globins
The
placenta
has four
separation
of
in
the
maternal
blood
Absorption of
Glucose
is
placenta
foetus.
soluble
acids
blood
so
vitamins
vitamins
are
so
it
by
glycogen
Amino
maternal
in
higher
concentration
diffuses
in
the
in
opposite
the
foetal
blood
facilitated
and
are
they
are
much
in
a
are
also
probably
to
absorbed
transfer
direction.

exchange
of
into
them
blood
diffusion.
is
used
higher
absorbed.
by
by
active
Fats
glucose
respiration
concentration
absorbed
absorbed
in
Some
and
in
by
fatty
foetal
acids
(see
in
placenta
blood
Ions
and
page
stored
the
transport.
pinocytosis
is

secretion
of

metabolism
blood
has
absorbed.
vesicles
into
a
across
lower
W
ater
foetal
blood
which
foetal
foetal
kidneys
the
amniotic
the
transport
and foetal
blood
fat
39).
and
than
and
them
across
the
the
start
potential
move
from
higher
to
hormones
and
energy
storage.
in
water
soluble
Antibodies
epithelial
foc us
cells
blood.
epithelial
water
will
has
between
the
Nilsson
photographer
moves
substances
maternal
Lennart
W
ater
systems
than
S tudy
are
and foetal
nutrients
absorbed
as
is
maternal
foetal
circulatory
dioxide
roles:
oxygen

across
biology
than
foetal
water
function
membrane
osmosis.
maternal
blood
potential.
and
by
urine
to
blood
is
about
produced
the
then
maternal
After
If
11
if
is
will
be
the
weeks
that
a
Swedish
has
specialised
in
foetal
water
blood
is
who
human
development.
photos
online.
Search for
his
the
released
into
cavity.
Link
The
foetal
placenta;
bilayers
metabolism
urea
of
and
the
produces
bile
carbon
pigments
capillary
and
also
epithelial
dioxide
diffuse
cells
which
through
into
the
diffuses
the
across
the
phospholipid
maternal
Read
blood.
pages
yourself
38
about
to
The
remind
across
membranes
the
placental
in
villi
the
have
amnion
carrier
The
of
to
exchanges
membranes. Cell
epithelium
39
amnion
also
forms
from
extra-embryonic
tissues
to
surround
proteins for facilitated
the
diffusion
foetus.
It
is
a
thin,
but
tough
sheet
of
tissue
that
is
transparent;
cells
secretes
a
uid
that
has
much
the
same
composition
as
tissue
uid.
contain
fluid
providing
a
affected
plasma
by
fills
sterile
the
mechanical
but
with
amniotic
environment
lower
damage.
protein
cavity
and
a
The
that
surrounds
cushion
uid
content.
is
The
for
the
derived
uid
the
so
it
is
maternal
provides
transport. The
mitochondria
energy for
active
to
transport.
foetus
foetus
from
active
many
This
provide
amniotic
and
it
a
not
blood
constant
Summary questions
temperature
exposed
to
for
the
foetus,
extremes
of
which
is
especially
important
if
the
mother
is
temperature.
1
Explain:
organ,
The
foetus
is
able
to
move
about
within
the
amniotic
uid
which
development
of
the
skeletal
and
muscular
systems.
The
tough
some
and
of
the
liquid
impermeable
through
until
the
about
20
skin
which
weeks.
The
does
not
foetus
uid
which
helps
development
of
the
swallowing
passes
through
the
foetal
gut
and
is
absorbed;
some
placenta
the
is
an
placenta
as
as
a
gas
an
exchange
excretory
surface
organ.
the
reex.
Explain
of
it
is
how
the
placenta
The
is
liquid
the
how
become
drinks
2
amniotic
ii
foetus
and
absorbs
why
helps
acts
the
i
and;
adapted for
exchange
of
then
substances.
urinated
into
movements.
for
its
the
amniotic
uid.
The
amniotic
cavity
independent
life
as
a
baby
The
and
after
foetus
its
also
uid
starts
help
to
breathing
prepare
the
foetus
3
Describe
blood
birth.
heart
The
amnion
breaks
during
the
early
stage
of
in
to
the
pathway
taken
the foetus from
the
placenta
by
the
and
back.
birth.
4
Describe
5
Explain
the
two
the foetus
roles
ways
may
composition
of
of
in
the
which
change
the
amnion.
the
amniotic
fluid.
167
2.6
Hormonal
control
The
Learning outcomes
production
hormones
On
completion
should
be
able
of
this
section,
you
produced
or
to:
breast
female

dene
the

name the
term
explain
how
sperm
control
feeding
a
continuous
spermatogenesis
intervals
and
reproductive
is
of
about
not
on
a
the
systems
are
is
month
‘pill’.
process
also
in
so
secretion
continuous.
women
The
the
who
changes
Oocytes
are
that
of
not
occur
are
pregnant
in
the
cyclic.
in
A
hor mone
It
is
is
a
signalling
molecule
secreted
by
an
endocrine
organ.
regulate
transported
in
the
blood
and
inuences
the
activity
of
target
tissues
humans
and/or

of
reproduction
hormone
hormones that
reproduction
to
at
of
hormones
organs.
The
hormones
that
control
the
activity
of
the
reproductive
regulate
organs
are:
gametogenesis


describe
the
role
of
hormones
gonadotrophin
hypothalamus
the
control
of
the
releasing
hor mone
(GnRH)
released
by
the
in
with
the
anterior
pituitary
gland
as
the
target
organ;
menstrual
it
is
a
decapeptide
with
10
amino
acids
cycle


state
the
role
of
gonadotrophic
in
hormonal
control
of
describe
the
secreting
role
of
the
females
in
their
the
Figure
are
activity
gonadal
the
gonads
(FSH)
interaction
and
–
the
testes
luteinising
and
ovaries;
hor mone
follicle
(LH)
are
between
the
hormones
is
complex
as
you
can
for
GnRH,
LH
and
FSH
on
the
cell
membranes
of
cells.
gonadotrophic
hor mones
secrete
the
growth
ovaries
and
are
steroids
oestrogens
and
released
by
cells
progesterone;
the
in
the
testes
gonads:
the
secrete
means
of
the
They
stimulate
gametogenesis,
the
development
of
gonads
primary
the
gland
2.6.1.
testosterone.
–
of
hor mone
receptors
target
ovaries
term
pituitary
foc us

stimulating
anterior
hormones.
There
The
the
placenta
see
S tudy
by
glycoproteins.
In
in
the
stimulating
reproduction

released
negative
inuence
feedback
hor mones
and
secondary
sexual
characteristics,
and
in
females
testes.
coordinate
interacting
the
activities
with
transcription
of
of
receptors
ovary
inside
and
cells
uterus.
and
They
function
‘switching
on’
by
the
genes.
Link
Cells
in
have
receptors
to
73 for
testosterone
S tudy
and
detect
organs
hormones.
information
on
the
enomroh
page
tissues
receptor.
noitartnecnoc
See
target
oestradiol
progesterone
foc us
0
14
28
time/days
The
changes
uterus
must
uterus
ovary
synchronised
ready
to
receive
if fertilisation
S tudy
and
the
so
that
the
enomroh
embryo
be
is
the
occurs.
noitartnecnoc
the
in
LH
FSH
foc us
0
Follow the
changes
in
of the four
hormones on these
14
graphs.
Figure 2.6.1
This graph shows the changes in the concentration of FSH, LH, oestradiol
and progesterone in the blood of a woman during a menstrual cycle
168
28
concentrations
Module
Before
puberty
these
concentrations.
secreted
by
the
concentrations
the
The
gonads
of
concentration
secretion
The
of
table
hormones
cells
in
and
GnRH.
in
the
the
Hormone
secreted
At
puberty
blood
details
of
a
low
the
increases.
by
but
hypothalamus
maintain
gonadotrophins
shows
are
the
the
very
secretion
This
of
biology
hormones
by
GnRH
stimulates
an
releasing
low
increases
increase
so
in
pituitary.
that
you
need
Site of
Target organ/
production
tissue
hypothalamus
pituitary
follicle
anterior
stimulating
pituitary
gonadotrophin
Reproductive
low
the
concentration
anterior
hormones
at
detect
3
to
know.
Action
gland
stimulates
anterior
pituitary
ovary
stimulates
oogenesis
testes
stimulates
Sertoli
ovary
stimulates
release
stimulates
interstitial
to
release
FSH
and
LH
releasing
hormone
hormone
(GnRH)
gland
(FSH)
luteinising
anterior
hormone
pituitary
(LH)
cells
of
to
develop
secondary
sperm
oocyte
cells
at
ovulation
gland
follicle
testes
cells
of
testes
to
secrete
testosterone
interstitial
oestrogen
follicle
in
cells
uterus
stimulates
repair
and
growth
of
endometrium
ovary
stimulates
secondary
progesterone
interstitial
testes
cells
testes
epididymis
epididymis
luteum
uterus
maintains
seminiferous
helps
in
corpus
in
and
regulates
growth
sexual
and
development
characteristics
spermatogenesis
and
of
primary
and
in females
sperm
maturation
in
endometrium
ovary
testes
regulate
sperm
production
tubules
increases
testosterone
ovaries
brain
one
interstitial
seminiferous
stimulates
cells
tubules
of
testes
of
sperm
many factors
stimulates
secondary
inhibin
Sertoli
cells
testis
follicle
in
in
hypothalamus
and
anterior
pituitary
anterior
pituitary
motility
in
determining
sex
drive
spermatogenesis
growth
sexual
and
development
characteristics
inhibits
secretion
of
FSH from
inhibits
secretion
of
FSH
in
of
primary
and
males
anterior
pituitary
ovary
169
Module
3
Reproductive
biology
Menstrual
The
changes
occur
within
as
the
menstrual
known
as
the
ovarian
Days
Hypothalamus
Anterior
1–5
secretion
secretion
of GnRH
that
known
uterine
starts
cycle
cycle .
pituitary
of
FSH
These
gland
and
cycle.
cycle ;
changes
oestradiol
secretion
inhibits
follicle
concentrations of oestradiol
14
secretion
of GnRH
FSH
are
of
LH
and
LH
starts
inhibits GnRH
ovulation
gradually
of
of
the
of
collectively
the
are
ovary
known
are
as
the
table.
cycle
menstrual phase:
primary
secretion
one
are
in
Uterine
menstruation
occurs
of
proliferative phase:
dominant
repair
into
and
growth
of
endometrium
–
release
of
oocyte
luteal phase:
LH
corpus
decreases
secretion
decreasing
uterus
in
Graaan follicle
secreted
concentration
in GnRH
uterus
occur
secretion
progesterone
decrease
the
summarised
develops
secondary
15–18
in
the
that
cycle
oestradiol;
inhibited by low
surge
and
changes
changes
development
FSH secreted, but gradually
of GnRH
ovary
follicular phase:
starts
follicle
5–13
the
Ovarian
LH
the
The
secretory phase:
luteum
secretes
glandular
activity
progesterone,
endometrium
reduction
its
in
maintains
concentrations
in
oestrogen
thickness;
oestradiol
secretion,
decrease
corpus
concentration
in
progesterone
secretion
progesterone
and
LH
inhibits
FSH
luteum
degenerates,
progesterone
18–24
secretion
not
leads
to
secretion
of
FSH
and
less
breakdown
secreted
of
endometrium
LH
inhibited
24–28
Negative feedback
The
secretion
limits
In
and
males
of
does
after
hormones
not
keep
puberty,
is
carefully
increasing.
the
controlled
This
is
hypothalamus
so
that
achieved
maintains
by
the
the
the
concentration
principle
of
concentration
in
the
negative
of
blood
stays
within
certain
feedback .
testosterone
between
300
and
−3
which
1000 µg 100 cm

the
hypothalamus

the
anterior
In
addition,
is
reduces
pituitary
the
the
set
the
reduces
hormone
point.
the
secretion
the
inhibin
If
of
concentration
GnRH
secretion
secreted
by
rises:
of
LH.
Sertoli
cells
inhibits
the
secretion
of
FSH
from
the
anterior
pituitary.
If
the
concentration
In
females
as
follows:
Days
1–5:
secreted
Days
low
by
6–13:
negative
the
the
FSH
on
a
of
point,
the
then
hormones
progesterone
theca
cells
hypothalamus
is
a
Day
11:
there
Day
14:
concentrations
170
is
set
and
the
is
hypothalamus
more
complex.
oestradiol;
increases
The
GnRH
the
changes
secreted
by
secretion
during
the
of
GnRH.
menstrual
hypothalamus;
FSH
cycle
and
are
LH
pituitary.
stimulates
there
the
between
concentrations
anterior
time
below
interaction
feedback
same
falls
surge
positive
in
of
LH
secrete
anterior
feedback
and
FSH
to
and
FSH
and
LH
that
oestrogen;
pituitary
causes
the
as
so
concentration
concentrations
concentration
of
of
of
LH
oestrogen
GnRH
to
increases
and
FSH
there
decrease.
increase.
concentrations
peak;
ovulation
occurs
and
follicle
cells
form
corpus
luteum.
is
a
But
at
Module
Days
15–28:
LH
stimulates
corpus
luteum
to
secrete
oestradiol
3
Reproductive
and
S tudy
progesterone;
feedback
on
if
the
concentrations
progesterone
another
does
hypothalamus
of
FSH
decreases
concentrations
and
fertilisation
of
and
and
LH
occur
,
leading
to
progesterone
anterior
decrease.
progesterone
cycle
not
As
pituitary
a
result
menstruation.
there
is
no
so
With
a
concentration
very
of
You
should
this
section
use
the
The
cells
has
implanted
in
of
the
which
the
trophoblast
ensures
the
foc us
pregnancy
endometrium,
it
must
announce
this
example,
secrete
survival
the
of
hormone
the
luteum
in
the
ovary
cycle
so
carrying
continues
to
ensuring
away
gonadotrophin
The
placenta
summarised
that
the
is
is
in
beyond
continue
the
lining
implanted
taken
an
over
end
of
the
embryo.
by
endocrine
the
the
to
the
of
secrete
by
stimulating
progesterone.
as
hCG
h
as
secreting
soon
a
of
does
of
as
is
the
choose
set
point
when
on
the
air
adjust
the
conditioning
This
the
not
you
the
set
the
temperature for
an
oven.
menstrual
break
down
chorionic
it
number
develops.
of
hormones
as
table.
gonadotrophin
with
week
secretion
placenta
organ
fourth
endometrium
The
Hormone
chorionic
the
point
chorionic
embryo
or
stimulation
set
concentration. You
temperature
corpus
the
its
the
gonadotrophin
in
loops.
secretion
desired
arrival.
information
draw feedback
starts.
hormones during
embryo
to
low
GnRH
In
Once
the
of
S tudy
Secretion of
foc us
negative
that
the
inhibition
exerts
biology
(often
standing for
known
human)
Target organ(s)
Function
corpus

luteum
in
ovary
progesterone
stimulates
maintain
uterus
continued

maintains

inhibits

prevents

inhibits
breasts

development
uterus

stimulates

sensitises
hypothalamus
and
secretion
pregnancy for rst
of
progesterone
three
to
months
endometrium
contraction
of
myometrium
menstruation
secretion
of GnRH
and
FSH
pituitary
oestrogen
at
anterior
and
pituitary
birth
of
milk
growth
glands
of
uterine
myometrium
to

inhibits

stimulates
stimulate
secretion
to
wall
oxytocin
muscle
of GnRH
that
is
secreted
contraction
and
FSH
hypothalamus
breasts
growth
of
ducts
Summary questions
1
Dene
the following
target organ
and
terms:
hormone,
endocrine organ,
6
negative feedback
Explain
how
controlling:
negative feedback
i
testosterone
is
involved
secretion;
ii
the
in
menstrual
cycle.
2
Name
the
hormones
that
control
reproduction
in
7
humans.
Describe
the
role
of
the
placenta
in
secreting
hormones.
3
Outline
uterus
the
changes
during
one
that
occur
menstrual
in
the
ovary
and
8
cycle.
Make
a
large
annotate
4
Explain
males
5
how
hormones
control
gametogenesis
copy
them
of
with
the
graphs
on
information
page
about
168
and
where
the
in
hormones
are
secreted,
stimulate.
Draw
where
they
act
and
what
they
and females.
Outline
the
activities
of
roles
the
of
hormones
ovary
and
in
synchronising
uterus.
the
on
the
x-axis
to
a
diagram
show
with
changes
the
in
same
the
timeline
uterus
and
the
ovary.
171
2.7
The
effect
of
maternal
behaviour
on foetal
development
A
Learning outcomes
foetus
interacts
placenta.
On
completion
should
be
able
of
this
section,
you
should
to:
explain
the
importance
nutrition
a
as
the
acts
good
surrounding
as
its
diet,
stay
overusing
behaviour
may
lungs,
entirely
through
and
excretory
healthy
and
not
legal
affect
world
gut
drugs
the
and
infant
take
abusing
(up
to
part
in
illegal
one
the
system.
Mothers
any
risky
drugs.
year
after
Effects
birth)
or
of
may
maternal
such
maternal
with
organ
maintain
behaviour
,
of

This
be
long-lasting
and
affect
a
person
throughout
their
life.
during
pregnancy
Maternal

outline
the
on foetal
alcohol,
illegal

effects
of
drug
development
nicotine,
other
including
legal
and
drugs
describe
the
effects
of
A
woman’s
There
is
on foetal
explain
why
some
an
and
During
the
increased
first
risks
to
any
diseases
for
unborn
She
is
some
women
talk
clinic. This
to
will
understand
nutrients
this
to
breasts
is
pregnant.
support
and
provided
the
foetus.
from
the
diet;
she
by
the
does
mother
not
to
make
use
of
stored
fat
and
stores
need
to
of
pose
at
advice
such
absorbing
as
calcium
it
as
is
nutrients
and
iron.
She
also
necessary
shown
in
to
the
from
her
diet.
becomes
T
owards
increase
the
intake
of
the
more
energy
end
and
of
certain
table.
the
at
help
the
Comments on
intake
during
pregnancy
energy
intake
antenatal
staff
you
topics
Function
given
energy
or
when
foc us
read
pregnant
clinics
and
placenta,
pregnancy
requirements
able
Nutrient
to
of
energy
uterus,
changes
children.
nutrients
should
for
the
months
additional
two’.
pregnancy
You
of
many
development
efficient
S tudy
six
through
demand
metabolism
micronutrients,
health
goes
cigarette
‘eat

metabolism
growth
without
smoking
nutrition
abuse
at
such
(provided
by
required for
growth
and
should
not
a
carbohydrates, fats
metabolism
of
uterus,
and
placenta, foetus
increase
until
the
last
to
in
this
proteins)
and
three
months
of
section.
breasts
pregnancy
about
protein
growth
as
of
blood
tissues,
in
both
and foetus
in
calcium
uterus
growth
and
such
additional
mother
then
by
day
a
day
pregnancy
muscle
and foetus
of
bones
of
no
as
extra
haemoglobin
in
both
needed
gut
is
efcient
women
and foetus
calcium
absorption from
more
mother
a
6 g
throughout
foetus
iron
and
800 kJ
at
deciency
should
risk
of
iron-
anaemia
take
a
supplement
of
iron
with
vitamin C
Women
have
Link
first
Read
on
about
page
11.
body
mass
index
(BMI)
12
such
are
per
weeks
as
develop
exposed
172
advised
400 µg
spina
into
at
to
day
of
the
one
pregnancy
bifida.
the
take
for
In
brain
surface
this
and
of
a
folic
acid
month
to
reduce
the
condition
spinal
the
cord
body
supplement
before
at
risks
the
to
becoming
of
neural
does
birth.
not
ensure
that
pregnant
neural
tube
close
tube
that
and
for
defects,
goes
properly
they
on
and
to
is
the
Module
It
is
not
necessary
to
increase
the
food
intake
by
very
much
during
3
Reproductive
the
S tudy
last
are
three
months
overweight
or
in
order
obese
to
gain
should
sufficient
probably
energy.
not
In
increase
fact,
at
all
women
and
losing
weight
during
pregnancy.
A
woman
of
normal
women
(BMI
of
18.5–24.9)
should
increase
by
11–15 kg
in
body
women
and
should
there
is
take
in
sufficient
sufficient
water
water
for
the
so
the
mother
amniotic
have
important
is
calcium,
diets
nutrients,
iron
and folic
acid,
such
put
not
the
dehydrated
in
mass.
as
Pregnant
who
weight
decient
range
foc us
who
should
Pregnant
consider
biology
health
of
their
children
at
risk.
uid.
Try
answering Question
page
176
to
work
out
6
the
on
effect
of
Drugs
such
A
drug
is
chemical
as
any
alcohol
Alcohol
and
on
to
the
is
it
the
crosses
as
the
on
the
illicit
A
and
and
very
the
This
so
drink
rare
body
enters
This
the
the
is
the
as
heroin
foetal
at
a
effects
blood
time
are
are
condition
modifies
medicines,
such
alcohol
(especially
that
includes
drugs,
foetus.
who
pregnancy
syndrome
Nicotine
and
alcohol
delivery.
into
body.
placenta
Mothers
during
alcohol
effects
the
metabolise
premature
taken
the
throughout
adult.
alcohol
in
nicotine,
crosses
distributed
able
substance
reactions
worse
caused
by
eight
and
affects
on
the
heavy
and
foetus
risk
is
developing
such
foetus
is
is
than
of
intake
weeks)
the
cocaine.
the
the
on
foetus.
drugs
circulation
before
increasing
first
or
legal
deciencies
of
foetal
(FAS).
drug
in
placenta
tobacco
and
products,
enters
the
such
foetal
as
cigarettes.
circulation
Like
having
alcohol
the
same
adults:
Summary questions

increases

restricts
heart
blood
rate
ow
to
the

increases
blood

increases
stickiness
extremities
Nicotine
through
so
reduces
the
the
ow
of
blood
increasing
through
the
pressure
risk
umbilical
of
of
platelets
blood
arteries
1
clots.
Explain
is
and
eat
placenta.
cocaine
pose
very
serious
health
risks
to
unborn
to
planning
and
a
acid
Heroin
why
given
drugs
in
cross
the
the
same
placenta
way
as
the
and
the
foetus
mother
.
This
becomes
means
after
on
birth,
more
shows
withdrawal
common
heroin
and
amongst
symptoms,
babies
of
such
as
women
severe
shaking;
dependent
on
cot
drugs,
alcohol;
intake
deaths
such
as
2
Find
of
the
out
monoxide
in
cigarette
to
form
haemoglobin
to
transport
the
blood
smoke
combines
carboxyhaemoglobin .
oxygen
by
up
to
irreversibly
and
monoxide
This
10
per
reduces
cent
the
and
ability
affects
last
three
the
effects
mothers
on
of
the
who
foetal
blood.
The
combined
effects
of
lead
to
the
umbilical
blood

placenta

restriction
vessels
are
series
of
of
smaller
than
had
blood
pregnancy.
your ndings
bullet
Find
out
as
a
points.
the
effects
syndrome
of foetal
and
make
a
list
following:
them.
narrower
Summarise
the
effects
of
the
normal
following
of
during
nicotine
4
is
drug
both
of

through
placenta
may
stimulate
foetal
heart
to
reduced
on foetal
energy
development:
intake,
nutrient
faster
deciencies,

increased
risks

increased
risk

decreased
of
of
miscarriage
death
of
and
foetus
premature
or
infant
birth
just
smoking
before
or
after
mass
at
birth
as
a
result
(IUGR)
decreased
of
intra-uterine
growth
retardation
to
infection.
and
Pathogens,
viruses,
which
immunity
alcohol,
illicit
cigarette
drug
taking.
birth
5

the
thalidomide
of
the
alcohol
beat
stop
increase
pregnancy.
Summarise
with
3
carbon
not
smoking
haemoglobin
and
until
about
drug
taken
maternal
do
are
children
Carbon
take folic
smoking;
the
cocaine.
Cigarette
pregnant:
the
months
child
diet;
stop
advice
are
children.
dependent
that
who
become
balanced
energy
drug
to
tablets;
drinking
The
the following
women
take
as
and
can
infect
precautions
to
bacteria
disease.
pathogens
placenta
What
such
cause
prevent
and
Find
out
cross
the
the foetus.
can
women
this?
173
2.8
Human
reproduction
The
Link
this
Can
and
you
name
any flowering
mammals
Look
at
page
flowering
that
are fully
150 for
an
plants
of
a
and
live
are
1
a
that
list
of
have
but
between
in
events
that
Put
these
you
–
events
it
is
help
time
the
you follow
during
the
time
mammals
aspects
some
to
the
changes
reproduction,
a
male
time
of
when
occur
in
the
sexual
sexual
sequence.
Letter
and
their
they
germinal
a
testes
a female
conception
conceive
a
to
child.
epithelium
in
A
produces
The
spermatogonia
to
the
help
you
plants
1°
foc us
organise
your
parts. The rst
gametogenesis
underlying
in
humans
first
one
has
been
done
in
part
males
sexual
Letter
germinal
by
epithelium
in
M
produces
oogonia
stored
in
B
zygote formed
C
2°
spermatocytes
to form
D
oocytes
2°
divide
to
E
oocytes
N
sperm
pass
and
oogonia
divide
O
spermatids
through
P
uterus
grow
into
1°
Q
oocytes
sequence
will
sexual
intercourse
sperm
ejaculated
–
F
sperm
enter
oviduct
G
ovulation
H
sexual
intercourse
sperm
deposited
R
show
in
and females;
semen
the
second
changes
part
that
will
occur
show
the
after fertilisation.
spermatids
into
differentiate
into
S
spermatozoa
spermatogonia
grow
1° spermatocytes
–
T
in
vagina
zygote
divides
2-celled
to form
I
embryo
1° spermatocytes
to form
divide
U
2°
spermatocytes
S tudy
foc us
internal
This
sequence
tells
a
story. There
examples
of
processes
can
learn
as
if
they
are
a
beginning,
middle
of
replication,
blastocyst forms
V
vesicles,
K
birth
W
stories
and
gland
and
end.
prostate
Think
J
uterus
Cowper’s
with
in
that
seminal
you
development
are
the
many
gland
release
transcription,
secretions
translation,
mitosis,
cannot
tell
able
write
to
174
to
and
mitosis
form
to
reproduction
here
owering
Event during
cervix
need
terrestrial,
reproduction
ovaries
fertilisation
two
their
of
reproduction
reproduction
epididymis
in
to
that
draw
sperm
You
in
understand
during
correct
implantation
S tudy
of
questions
reproduction
and
are
adaptations
knowledge
foc us
line for
from
some
are
your
groups.
reproduction
occur
and
organise
A.
Event during
To
are
sexual
both
you
different
There
humans
to
help
plants
very
there
similar
.
apply
will
X).
for
S tudy
land,
reproduction
is
to
on
below
owering
They
remarkably
principles
(A
Most
land.
comparisons
sexual
This
questions
area.
on
dispersal
that
make
plant.
and
subject
they
aquatic?
example
tasks
summary
the
meiosis.
story,
about
it
you
in
If
will
the
you
not
be
exam.
embryo
foetus
develops
into
a
L
Module
2
Make
a
table
Include
when
the
precise
starts;
gametes
site
of
of
Identify
oogenesis
headings
time
of
of
for
the
produced
production
production
length
3
of
compare
following
process
number
in
to
from
equal
rows:
cycle
each
time
when
cell
gonad;
or
Reproductive
biology
spermatogenesis.
your
life
within
gametes;
and
3
from
names
unequal
of
the
the
each
of
life
process
diploid
other
division
cycle
stops;
of
cells
cell;
involved
cytoplasm;
time.
each
of
A
Secreted
B
Stimulates
C
Made
by
the
following
interstitial
secretion
from
hormones
from
these
statements:
cells.
of
FSH.
cholesterol
in
the
corpus
luteum
to
maintain
endometrium.
D
Stimulates
repair
and
growth
of
the
endometrium
after
menstruation.
E
Acts
by
negative
pituitary
F
4
Secreted
The
a
by
negative
why
it
ow
give
the
a
Explain
chart
a
meiosis;
(single
products
of
and
its
a
Sweet
zygote,
to
the
to
within
of
anterior
FSH.
narrow
limits
concentration
prevent
changes
of
in
males.
GnRH
is
polyspermy.
that
an
occur
oocyte
involved
tubal
to
delivery
to
of
after
until
with
ligation,
the
a
the
sperm
zygote
following
barrier
cell
divides
methods
methods
and
a
gamete;
of
that
owering
for
type
fuse
number
internal
the
the
oocyte
precise
your
of
of
plants
table:
and
site
of
fertilisation
together;
site
of
chromosome
development;
of
mother
primary
to
meiosis
mother
of
(2n = 90)
cell,
oocyte,
trophoblast
method
the
in
sets
in
of
a
of
owering
human
the
of
a
plant
ovum.
following
and
human.
mother
cell,
production
a
mature
each
secondary
cell,
a
and
pollen
endosperm
in
cell
produce
location
potato
zygote,
embryo,
role
megaspore
sweet
cell,
oogonium,
male
in
headings
embryo.
megaspore
8-celled
row
fertilisation;
primary
in
reproduction
structures
site
from
a
of
of
compare
show
number
sexual
following
names
sac
antipodal
Human:
the
of
from
potato:
gamete,
secretion
the
surrounding
compare
nutrients
table
from
prevented.
principles
product(s)
embryo
ploidy
LH
embryo.
fertilisation;
meiosis
Make
to
diagrams
mature
kept
how
is
vasectomy,
double);
providing
Make
cells
Include
fertilisation;
of
pills.
method
or
show
biological
table
mammals.
is
important
to
follicle
contraception:
Make
is
two -celled
the
secretion
feedback.
Explain
a
inhibit
inhibit
show
b
contraceptive
10
to
polyspermy
of
9
GnRH
loop
how
Make
to
to
Explain
to
8
of
cells
a
reaches
7
Sertoli
feedback
controlled
6
by
feedback
ovulation.
concentration
Draw
5
after
cell,
male
meristematic
oocyte
(two
spermatogonium,
cell.
locations),
primary
Link
spermatocyte,
secondary
spermatocyte,
spermatozoon
(numerous
sites).
11
Read
Describe
how
Compare
embryo
is
the
the
placenta
functions
of
acts
the
as
a
life
placenta
support
with
the
system
ways
for
in
the
which
foetus.
a
plant
page
about
the
making
80
to
remind
human
your
life
yourself
cycle
before
table.
supported.
175
2.9
Practice
Human
1
a
Compare
in
b
the
Sperm
after
cells
i TWO
reaching
oocyte;
in
ii TWO
the
site
ovaries
5
of
that
a
systems.
corpus
capacitation
b
capacitation.
methods
that
c
the
and
to
crosses
women
drink
during
gonadotrophin,
and
progesterone.
in which
membranes of the
placenta. Give
why
not
the following
chorionic
oestrogen
epithelial
in the
Explain
of
FOUR different ways
substance that
prevent
in
roles
human
luteum,
Describe
villi
sperm
of fertilisation
the
cross the
different
prevent
Describe
pregnancy:
reproductive
a variety
methods
reaching
and
process of
happens during
work
ways. State
an
testes
into the female
Describe what
oocyte
the
questions:
reproduction
reproductive
go through the
Contraceptives
an
of
and female
ejaculation
tract.
c
the functions
male
exam-style
an
in
are
example of
a
each way you describe.
advised
alcohol
substances
chorionic
during
not
to
smoke
pregnancy.
oviduct.
6
2
a
Name
the
cells formed
spermatogenesis
in
oogenesis
immediately
after
a
and
each
of
these
b
State ONE
between
growth
phase,
meiosis
I,
of
the
amnion
and
amniotic uid.
processes:
mitosis,
State THREE functions
meiosis
a
II
plant
similarity
the
ways
embryo
in
and ONE
which
receive
a
difference
human foetus
nutrients
during
and
their
development.
b
Explain
the
signicance
of
mitosis
and
meiosis
in
c
spermatogenesis.
Explain
their
c
Describe
the
role
of Sertoli
cells
in
a
Explain
how
control
of
negative feedback
the
menstrual
is
involved
in
in
woman’s
the
diet
menstrual
can
expect
may
adversely
in
menstrual
two
cycle.
named
Explain
of
cycle
to
secondary
oocyte
is
questions
prepare
be
of flowering
yourself for
may
surrounded
ask
you
to
compare
the
and
type
of
humans.
question
Make
by
sure
doing
8–11
in
the
Summary
section
on
page
175.
in
which
interrupted.
released from
by
plants
this
cause
an
ovary
a
Describe
and
a
zona
pellucida
explain TWO
ways
the
at
composition
ovulation
that
how
nutrients
7
A
care
affect
Questions
deciencies
c
take
the
you
the
should
cycle.
reproduction
Deciencies
a
women
pregnancy.
Link
You
b
pregnant
during
seminiferous
tubules.
3
how
diet
of
the
amniotic uid
changes
during
and
pregnancy.
follicle
cells.
b
i
Describe
how
a
sperm
cell
penetrates
Describe
of
surrounding
layers
and
enters
the
the
a foetus
an
Explain
how
polyspermy
is
a
Describe
b
i
State
the
a
human
process
site
of
of
found
implantation.
secretion
chorionic
Explain
how
of
the
gonadotrophin
the
secretion
of
genes
(hCG).
hCG
in
oocytes
hormone
During
are
do
cycles
pregnancy
not
normal
need
become
to
the
mother
circumstances,
to
take
anaemic.
iron
ii
many
iii
is
iron
300 mg
to
of
iron
8
a
the foetus.
pregnant
supplements
Explain
necessary for
pregnant
women
unless
alcohol;
ii
a
a foetus
may
excessive
diet
decient
in vitamins
mitochondrion.
mitochondria
only
is that
(mtDNA)
is
the
Both
but
inherited from
mtDNA
is
loop
of
sperm
DNA
and
mitochondrial
the
oocyte.
Explain
inherited from the female
only.
the foetus;
if
Outline
the
roles
of
the following
Explain
how
hormones
the
are
LH
and
concentrations
controlled
within
hormones
in
FSH.
of
these
narrow
limits.
why
women
suffer
each
DNA
spermatogenesis: GnRH,
b
they
do
not
the
need
mother
A
type
which
to
take
supplements;
anaemic.
176
i
causes
c
i
iron
development
stop.
approximately
transported from
Under
of
have
are
it
parent
menstrual
c
the
consumes:
pregnancy.
Mitochondrial
how
ii
mother
prevented.
c
4
the
oocyte.
during
ii
if
cytoplasm
quantities
of
consequences for
these
becomes
of female
is
injected
contraceptive
into
muscle
is
Depo-Provera
tissue
every
12
weeks. Suggest:
i
how
this
contraceptive
ii
why
one
injection
last for
as
long
as
of
12
prevents
this
pregnancy
contraceptive
weeks
can
Module
iii
how
the
may
be
effectiveness
of
this
contraceptive
a
i
Plot
determined.
ii
9
The
graph
shows
changes
a
graph
number
in
the
concentrations
Calculate
hormones
during
a
woman’s
menstrual
to
show
Reproductive
the
changes
biology
in
the
mean
oocytes.
the
percentage
decrease
in
between
birth
the
of
mean
four
of
3
number
of
oocytes
and
cycle.
age
iii
42
years.
Suggest
why
enomroh
noitartnecnoc
numbers
b
State
of
there
the functions
the female
was
a
decrease
in
the
oocytes.
of
the following
reproductive
structures
in
system:
oestradiol
progesterone
0
14
i
oviduct
ii
uterus
iii
cervix.
28
time/days
c
A
woman
while
she
is
advised
is
pregnant. Outline
to
stop
smoking
the
cigarettes
reasons for
this
enomroh
noitartnecnoc
advice.
LH
11
a
i
Draw
a
labelled
structure
FSH
ii
Explain
of
a
how
diagram
human
the
to
show
sperm
sperm
is
the
cell.
adapted
to
its
function.
0
14
b
28
time/days
Figure 2.9.1
Describe
oocyte
This graph shows the changes in the
It
is
how
the
structure
differs from
estimated
that
concentration of FSH, LH, oestradiol and progesterone in the
that
there
of
are
of
a
a
human
sperm
more
secondary
cell.
than
20
million
3
sperm
in
each
1
of
cm
semen.
In
women
who
are
not
blood of a woman during a menstrual cycle
pregnant
a
Describe
and
LH
the
changes
during
the
in
concentrations
menstrual
of
FSH
secondary
Explain
half
of
the
the
roles
of
FSH
menstrual
and
LH
during
the rst
Describe
how
the
oocytes
Explain
why
change
concentrations
if
are
the
‘pill’,
one
released
or
each
two
month.
many
more
sperm
are
produced
than
cycle.
of
a
Describe
how
the
woman
male
gametes
are
produced
in
the
mammals
hormones
taking
oocytes.
12
c
not
cycle.
c
b
or
(details
of
the
stages
of
meiosis
are
not
becomes
required).
pregnant. You
may
draw
a
sketch
graph
to
help
b
your
Explain
how
a owering
10
The
table
changes
the
production
of
male
gametes
in
answer.
shows
in
the
numbers
results
of
of
a
oocytes
study
in
the
into
the
ovaries
male
gametes
in
differs from
the
production
of
mammals.
during
c
reproductive
plant
Describe
how
male
gametes
reach
the
site
of
life.
fertilisation
Age/years
Mean
number of oocytes
birth
712 000
7
468 635
14
402 067
21
175 700
28
166 231
35
89 145
42
39 874
49
9956
56
3450
in
mammals
and owering
plants.
per female
177
Glossary
chromosomes
move
apart
reproduction
when
a
cell
divides
into
A
(meiosis
acrosome
sperm
sac
cell,
activation
be
of
enzymes
on
derived from
energy
overcome
a
energy
before
a
head
of
a
lysosome.
that
the
site
part
of
where
has
a
reaction
molecules
gradient
using
movement
against
a
to
DNA,
RNA
from
main
any
a
and ATP
allele
an
There
roots
component
that
other
they
be
two
and
a).
Some
alleles,
alleles
which
has
e.g.
of
genes
the
three
(I
a
(or
to
resistant
use of
gene
group
B
I
O
and
I
that
has four
pollen
).
biological
species
interbreeding
features
in
sexually
to
see
by
or
common
a
pair
together
the
blastomere
that
bacteria
antibiotic;
a
mutant
with
RNA
term
of
and
gene
to
used
the
on
of
alleles
of
a
gene
have
different
a
nucleotide
sequences,
the
same
locus
individual.
bulk transport
to
describe
the
quantities
of
membranes
given
as
homologous
term
techniques
atoms
used
used
microorganisms
tissue
chromosomes.
embryo
formation
of
a
of
the
species from
populations
that
as
a
isolated from
one
another
culture
conditions
unwanted
asexual
by
a
zygote.
enlarges
separate
movement
substances
by
is
by
of
large
across
endocytosis
cell
or
C
to
and
are
occur
as
they
to
and
not
viruses,
reproduction
cells
through
in
reproductive
tract
so
the
they
are
in
to fertilise
an
oocyte.
sterile
contaminated
bacteria
sperm
pass
ensure
cells
cultured
change
to
compound
by
when
carbon
monoxide
or fungi.
combines
are
a
reproduction
outgrowth
in
formed
new
that
asexual
carboxyhaemoglobin
speciation
of
exocytosis.
able
allopatric
cells
numbers
carbon
aseptic technique
that
on
the
and
I
cells formed
off
on
female
occupy
associate
deoxyribose.
describe
but
of
of
small
breaks
that
DNA
they
prophase
divisions
form
translation.
DNA;
the
ball
repeated
and
two
in
one
offspring;
species.
meiosis
animal
budding
when
bases
codon
during
the
3′–5′,
three
blastula
hollow
antibiotic.
pairs
of
share
reproduce
blastula.
have
of
and
homologous
as
during
capacitation
The
of
of
that
produce fertile
metaphase
inhibit
population
organisms
morphological
bivalent
ability to withstand or
group
referring
produced
ability of
an
polynucleotides
5′–3′
have
blood
,
loss
produced
kill
bacteria
gives
orientation
gene.
a
of
bacteria.
antiparallel
of
involving
produce
compound
messenger
grow from
A
gene
of
survive
tRNA
the
stems.
alternative form
multiple
a
anticodon
grow
than
are
result
chromosomes.
stamen
which
a
chromosomes
growth
that
(adenosine
roots
may
(e.g. A
a
breakdown that
root;
and
sacs
antibiotic
to
respiration.
base,
structure
(tap)
leaves
of
antibiotic resistance
membrane
triphosphate).
adventitious
individual
synthetically)
of
concentration
cell
energy from
purine
a
chromosomes
numbers
mutation
microorganism
across
a
of
all
equal
grains.
takes
shape
not
in
part
pollen
enzyme
complementary
active transport
of
an
the
substrate.
adenine
gain
anther
molecule
place;
present
or
can
proceed.
active
aneuploidy
two.
chromosome
must
reaction
I).
reproduction
irreversibly
with
in
haemoglobin.
geography;
see
sympatric
speciation.
which
new
individuals
are formed
carcinogen
amino
acid
activation
attachment
of
from
one
parent
without fusion
cancer,
amino
acids
to
specic
gametes,
tRNA
e.g.
binary ssion,
e.g.
vegetative
molecules.
tissue
that
autosome
surrounds
the foetus
enclosing
a
exist
in
any
sex
chromosome
chromosome;
cavity lled
with
amniotic
female
homologous
in
pairs
appearance
that
a
polysaccharide
may
that
have
one
although
different
amylose forms
starch;
they
or
alleles
of
of
branched
chain
more
a ower
style,
ovary
ovules.
reactions
biological
that
break
molecules
down
into
the
ones.
carry.
catalyst
composed
in
stigma,
they
smaller
with
genes
of
match
large
amylopectin
organ
other
catabolism
exactly
uid.
and
autosomes
with
amniotic
causes
radiation.
composed
than
that
chemicals
reproduction.
carpel
extra-embryonic
agent
certain
budding,
ionising
amnion
any
of
any
substance
that
increases
of
the
rate
of
a
chemical
reaction;
see
B
α-glucose.
enzyme.
amylose
a
polysaccharide
that
with
bell-shaped
amylopectin forms
starch;
describe
of
unbranched
chain
of
α-glucose
a
term
normal
used
cellulose
to
distribution
in
a
a
polysaccharide
straight
chain
of
composed
of
β-glucose.
in
feature
a
curve
composed
showing
continuous
variation
centriole
organelle that organises
helix.
in
anabolism
reactions
that
build
which
biological
drawn
through
microtubules of the
of
a
histogram
is:
symmetrical
nuclear division
the
mean,
mode
and
median
all
e.g.
protists
plants do
coincide.
stage
of
nuclear
division
spindle for
some
and
eukaryotes,
animals; owering
sister
chromatids
move
form
of
asexual
centromere
and
meiosis
II)
and
have
part
of
centrioles.
a
chromosome
apart
where
(mitosis
not
in
binary ssion
178
in
ones.
anaphase
which
the
molecules from
and
smaller
curve
up
blocks
larger
the
sister
chromatids
are
joined
Glossary
and
to
where
the
chromosome
spindle
during
chemotropism
chemical
growing
by
growth
gradient,
towards
is
attached
nuclear
division.
response
e.g.
pollen
chemicals
to
a
secreted
homologous
from
I
of
chromosomes
of
meiosis
crossing
chorion
attachment
that
into
chorionic
maternal
tissue
tissues
to form
the
structure
the
number
of
of
a
a
change
chromosome
chromosomes
to
or
in
to
the
chromatid
one
structures
of
comprise
a
chromosome;
sister
the
joined
at
proteins
the
that
packaged
and
in
process,
producing
tissue
asexual
and
up
have
or
natural
genetically
culture
or
or
articial,
identical
of
of
cells
codes for
an
amino
in
RNA
cytosine
acid;
see
have
one;
stores
of
a
in
of
a
a
plant.
and
meiosis
that
is
such
I;
cut
complete
off
of
shoot,
and
usually follows
of
into
division
meiosis).
like
forces
of
molecules,
attraction
DNA
e.g.
between
and
a
a brous
protein
RNA.
to
tendons,
skin
and
that
has
many
other
more
than
one
amino
mutation
a
substrate for
base
pairs
reducing
activity
of
see
or
an
of
both
e.g.
positive
water;
see
the
by
a
selection
in
a
population
of
is
an
rare
two
glycosidic
changes
increase
in
over
the
allele(s).
sugar
of
which
population;
molecule formed
monosaccharides
bond;
sucrose
is
an
feature
which
human
any
population
which
two
most
of
may
lead
to
in
the
selection
is
in owering
nucleus
a female
male
which
range
species;
of
other
a
common form.
plants fusion
with
a
e.g.
selection
extremes
of
the
in
categories
groups.
selection
the
variation
distinct
intermediates,
blood
favours
has
one
male
gamete
gamete
gamete
and
nucleus
diploid
nucleus
to form
a
with
triploid
triplet/
loss
of
one
in
a
gene;
syndrome
condition
caused
(or
leads
to
a
chromosome
mutation;
in
most
a
caused
by
an
additional
mutation.
chromosome
active
acid
(DNA)
No.
21.
a
an
nucleic
enzyme;
with
charges,
there
joining
cases
deoxyribonucleic
so
sets
acid.
that
frameshift
with
as
Down’s
more)
competes
in
or
endosperm.
each
tissues
substance
nucleus
rare form
by
by
inhibitor
male
genetic
organs.
competitive
site
the
connective
deletion
and
to
cross-
plants
bond.
frequency
a
codon for
tissue,
refers
gives
code
strength
a
two
double fertilisation
D
code
or
selection
a
result
time
the
that
become
hermaphrodite.
molecule
against
water.
degenerate
collagen
either
having
formation
base,
anticodon.
cohesion
a
disruptive
nuclear
pyrimidine
of
promote
are
negative
without
plant; form
cytoplasm
which
to
example.
propagation.
component
to
cell
disaccharide
as
by
change
discontinuous variation
plant,
division
and
a
hydrogen
as
a
non-sister
during
dipole
favours
homologous
of
not
of
process
in owering
plants
directional
pollen
separate
breakage
the
cells
method
diploid
and
endosperm.
transfer of
parts
root
a
of
have
before
chromosomes.
plants
chiasma.
vegetative
(mitosis
bases
nutrient
not
the
of
cytokinesis
two;
plants
a ower on
into
in
individuals
three
and
seeds
die
cells.
pollination
female,
phase
anther of one ower to
part
grown
maintain
secretory
embryo owering
and
do
grains from
in
to
dioecy
which
dicotyledonous
cross-pollination
leaf
(see
nuclei.
reproduction.
group
that
cuttings
loosely
of
of
energy
in
body’
remains
organism
monocotyledonous
results
is
interphase
during
chromosomes
(see
that feature
unspecialised
ovulation;
cotyledons,
chromatids
histone
‘yellow
ovary from
after
leaf
seeds
two
form
show
differentiation
early
cycle.
crossing over
non-
eukaryotic
chromatin
tightly
euchromatin)
cloning
cotyledon
exchange
DNA
heterochromatin)
that
sister
make
the
progesterone
uterine
stigma
double-stranded
see
chromosomes;
codon
thread-like
centromere
chromatids.
chromatin
in
two
the
or
not
reproducing.
intentional
ovum
literally
in
the follicle
seeds
nucleus.
that
luteum
plant;
mutation
to
prevents
specialised
that forms
of
that
extended
that
includes
endometrium
villi.
chromosome
so
of fertilised
secretes
results
often
method
embryo.
of
during
over.
extra-embryonic
grows
between
means;
any
pregnancy
corpus
point
prophase
natural
include
loss
tube
ovary.
chiasma
or
acid
that
is
the
substance
of
non-competitive
E
inheritance;
composed
of
two
inhibitor.
polynucleotides
complementary
used
to
describe
hydrogen
‘match’
between
two
molecules
together’,
e.g.
enzyme
bonds
in
by
the form
embryo
of
a
that
sac
mother
divides
by
cell
meiosis
diploid
cell
to form four
that
double
‘t
connected
the
helix.
nuclei
three
of
which
abort;
the
and
diabetes
mellitus
disease
caused
by
a
remaining
nucleus
divides
by
mitosis
substrate.
lack
condensation
reaction
a
type
of
insulin
which
results
in
of
a
molecule
to
of
that
variation
in
shows
a
between
range
two
many
intermediates,
to
promote
in owering
anthers
eight
embryo
sac.
nuclei
within
the
cross-
embryo
sac
plants
in
formed
(megaspore)
not
owering
by
meiosis
in
an
spore
ovule
and
stigmas
do
plants;
contains
in
the female
of
at
the
same
time;
see
gamete
and
is
the
site
of
double
extremes
protandry
with
to form
a
ripen
phenotypes
to
water.
which
feature
cells
insulin.
method
pollination
continuous variation
of
the
dichogamy
elimination
inability
of
respond
reaction
or
e.g.
and
protogyny.
fertilisation.
human
differential
survival
survival
of
endocytosis
movement
of
substances
height.
individuals
contraception
prevention
(fertilisation)
a
particular
into
a
cell
inside
vesicles formed
of
feature
conception
showing
by
whereas
individuals
who
do
articial
179
Glossary
from
cell
surface
phagocytosis
endometrium
uterus,
blood
fusion
of
diploid
inner
lining
of
triploid
plants
a
that
male
nucleus;
of
gamete
grows
energy
in
some
wheat,
in
others,
during
embryo
e.g.
within
endosymbiosis
such
as
prokaryotes
of
that
reaction
the
without
of
it
is
an
substrate;
epistasis
see
one
interaction
loci
in
during
proteins
bilayer
or
cycle
by
who
has
of
pituitary
up;
reading frame
mRNA for
in
a
half
of
pairs
in
of
in
loss
of
germ
etc.
is
genetic
and
constitution
being
as
to
the
of
alleles
considered, for
and
aa
allelic
cells
or AABB,
and
aa
are
pairs.).
that
an
line
gene therapy
allele
into
line
gamete
by future
mutation
in
gestation
a
give
rise
to
insertion
of
and
it
mutation
gamete-forming
themselves)
see
be
that
cells
and
somatic
period
may
(or
in
is
mutation.
length
of
time
(conception)
birth.
globular
is
protein
soluble
or
metabolic
in
near
haemoglobin,
at
so
generations.
between fertilisation
amino
having
process
cloning;
restricted
cells
spherical
the
of
generation
replication
(AA, Aa:
to
inherited;
in
acids
G
genes
genes
line
that
between
the
gametes
its
the
the
occurs
effect.
site.
by
and
asexual
and
example AA, Aa
germ
of
codons
amino
in
of
DNA
generation
organism
organism
inherited
that
sequence
polypeptide
catastrophic
so
bases
occur
of
or
to
in
gametes.
and
ovulation).
gain
assembly
alters
that
material
mitosis.
referred
ovaries
(before
base
are
an
generation
AaBb,
pregnancy.
anterior
mutation
more
generation
in
reproduction
of
condition
maintenance
genetic
genotype
of
hormone
during rst
used
association
which
of
mother
changes
gametogenesis
different
a
activity
a few
being
to
germ
ovary
acids
active
is
has
an
of
phase
frameshift
that
metabolic
and
from
it
and
stability
identical
maintained
syndrome
secreted
inuence
changed;
enzyme
when
not rm
phospholipid
child
genetic
cells
is accid
is
follicle-stimulating
the
enzyme-substrate
between
that
chain-
spherical
arrangement
alcohol
follicular
ancestors
proteins,
temporary
a
a
testes.
and
RNA.
complex
by
abused
to
itself
cell
water,
alcohol
(FSH)
a
than
protein
has
membranes.
that
organelles,
and
turgidity.
shown
seeds,
of
menstrual
of
are
plant
the uid
cell
water
collagen.
mosaic
seed.
catalyst
rate
its
foetal
all
and
cells.
enzymes
made
e.g.
development
entered
biological
increases
in
remains
originated from
eukaryotic
most
the
theory
mitochondria
chloroplasts,
enzyme
and
uid
a
barley
legume
growth
lost
by
nutrients for
seeds,
a
structural
in
rather
see
not full
in
and
and
and
as
such
shape
shape;
and
is formed
cereals
of
like
the
tissue
germination
used
of
glands
protein
insoluble
accid
the
store
rice;
is
vessels.
owering
a
brous
see
pinocytosis.
composed
endosperm
as
membrane;
and
water
protein
and
spherical
has
a
shape,
e.g.
enzyme.
of forming
glycogen
expression
a
polysaccharide
composed
gametes.
of
a
gene
is
inuenced
by
of
another.
gene
equatorial
plate
see
metaphase
a
length
of
keeping
enzyme
solutions
separate
temperature
before
codes for
to
at
(such
as
those for
RNA
RNA
and
stains
less
darkly
and
covalent
animals.
bond
two
sugar
molecules,
e.g.
in
not for
letters
are
used
hormone
secreted
structural
genes,
any
hormone
to
of
designate
DNA;
a
and
gonadal
packed form
bacteria, fungi
bond
sucrose.
polypeptides;
loosely
α-glucose;
enzymes),
transfer
together.
euchromatin
in
between
code for
of
a
a
some
chain
structural
mixing
ribosomal
them
refers
glycosidic
but
specic
that
branched
found
this
and
genes
substrate
DNA
plate.
polypeptide;
equilibration
a
by
the
gonads,
e.g.
e.g. A/a,
testosterone,
than
progesterone.
B/b.
gonadotrophic
heterochromatin.
gene
eukaryote
organism
that
has
mutation
nuclei
and
to
sequence
of
a
such
as
mitochondria;
gene
mutant
allele
of
that
adjective from
and
techniques
wall
of
pollen
movement
of
engineering
organism
of
a
cell
inside
cell
surface
insert
cure
or
an
to
(ovaries
e.g.
LH
and
FSH.
vesicles
inuence
pituitary
nucleus
haploid
nucleus
hypothalamus
of
in
secreting
anterior
gonadotrophic
grain
that
divides
to form
the
in
that fuse
hormones
–
FSH
and
two
LH.
male
gamete
nuclei
in
pollen
tube.
guanine
code
sequences
of
three
of
(A, T, C
of
ovum
the
20
and G)
amino
in
DNA
acids
in
that
a
purine
base,
a
component
bases
F
nucleus
by
activity
disorder.
membrane.
pronucleus
secreted
a
substances
genetic
female
gonads
allele
treat
to
pollen
with
to
to
grain.
generative
out
testes),
hormone
an
genetic
exocytosis
of
of
eukaryote.
into
outer
activity
gonadotrophin-releasing
genetic
exine
hormone
pituitary
gene.
see
using
anterior
giving
prokaryote.
eukaryotic
by
inuence
gene therapy
hormone
the
membrane-bound
a
organelles,
change
released
nucleotide
with
a
cells
DNA
and
RNA.
code for
proteins;
H
after fertilisation
before rst
mitosis
DNA
occurs.
fertile
the
period
period
menstrual
of
cycle
may
about
ovulated
oviduct.
180
be
time
during
occur
as
or
is
of
and
genetic
three
oocyte
in
the
is
often
genes
bases
codons
in
engineering
gene from
when
fertilisation
to
groups
one
used
in
to
triplets
in
mRNA.
the
context
of
to
of
a
another;
moving
unrelated
bacterium.
haemoglobin
transfer
organism
between
human
are
species,
composed
in
a
globular
of four
combination
responsible for
e.g.
and
carbon
protein
polypeptides
with
a
haem
transport
dioxide.
of
each
group;
oxygen
Glossary
haploid
of
a
organism
cell
chromosomes
organisms
sets
as
(or
sex
or
of
industrial
an
unpaired
the
stains
a
stigmas
darkly
method
are
number
of
male
in
at
packed form
in
the
to
nucleus.
a
which
heights
e.g.
homologous
same
a
that
position
in
sequence;
same
genes
two
may
have
of
and
the
be
the
division
and
the
genes
alleles
different
on
of
between
of
transfer
bacteria,
of
a
usually
also
pathogen
found
species
an
a
(animal)
endocrine
wall
of
or
tissue;
chemical
organ
activity
used
one
species
grain.
acts
and
that
is
only
that
between
to
to
maintain
of
target
chemical
unspecialised
target
tissues
a
tissue
lacunae
in
maternal
is
and
process,
such
partially
negative
partially
positive
collective
effect
bonds
model
of
a
‘lock’
and
site
chemical
specialise.
RNA
transcription
assembly
the
of
to
take
amino
chemical
organisms;
of
plate
plate
of
a
cell
arranged
and
DNA
to
reactions
see
nuclear
are
in
division
arranged
centre
region
where
during
of
in
on
cell.
across
the
chromosomes
metaphase
meiosis;
(enzyme)
see
also
of
known
as
plate.
and
bres
arranged
made
into
of
globular
tubular
‘key’
structures; for
the
cells
divide
catabolism.
support,
shape
and
induced t.
movement
of
of
to
of
water.
type
in
together
proteins,
locus
hydrolysis
which
chromosomes
proteins
(substrate);
DNA
active
substrate t
many
stabilises
ability
form
stage
microtubules
and
that
uterus
any faster.
hydrogen
like
hydrogen
proceeding
key
and
proteins from
all
in
equatorial
and
changes
enzyme-catalysed
atom
enzyme
atom;
make
occur
mitosis
lock
a
meiosis
as
are
a
of
separate.
therefore
biological
an
is
in
attraction
reaction,
between
to
centre
a
number
blood.
that
in
or
meiosis
unspecialised
cells
during
metaphase
growth
the
of
haploid.
ovary
retain
RNA
metaphase
any factor
to
prevents
bond
the
the
plant.
hydrogen
to
the
cells
produce
messenger
which
supply
to
or
released
elsewhere
to
chromosomes
division
the
that
metaphase
of
and
rise
and
chromosome
cycle
within
anabolism,
within
are
the
genetically
chromatids
plants
that
blood
there
gives
division
second
II
metabolism
space
which
halved
ribosomes.
organ
cells
in
acids
species.
any
is
another
diploid
instructions for
between
the
and
e.g.
produced
populations
released
into
one
in
human females.
and
methods
are
homologous
which
occur
island.
speciate
separate
to
separate
in
in
number
that
division
chromosomes
bivalents
the rst
I
which
meiosis
in
variation
interbreeding
shortest
and
nuclear
nuclear
generated;
meristematic
a
limiting factor
the
in
of
nucleus.
menstrual
mechanisms
placenta full
(plant)
inuence
meiosis
variation
is
is
nuclei
halved,
pollen
in
organ;
inuence
growing
when
one
four
parent
species.
on
to form
different
L
to
by
cycle
which
allows
lacuna
by
or
species.
next.
populations;
to
a
between
individuals.
hormone
cell
of
refers
breeding
populations
within
of
the
endemic
prevent
plasmids;
transmission
island
type
homologous
variation
classication.
isolating
the
pair
chromosomes
stage
and
inner
within
same
chromosomes.
the form
stage
grow
the
which
between
used for
intraspecic variation
same
the
the
horizontal transmission
genes
interphase
intine
of
have
centromere
the
often
different
their
pair
meiosis
polluted
breeding
varieties
between
sugar
glucose.
pair
chromosomes
shape,
a
of
as
chromosome
different
replicate;
anthers
different
bodies
interspecic variation
6-carbon
molecule,
against
between
cells
promote
adaptation
black
background.
individuals,
and
in owers.
hexose
having
interbreeding
tightly
cross-pollination
melanism
animals
camouage
polyploid
half
organs.
heterostyly
and
in
set
having
heterochromatin
DNA;
nucleus
cells).
hermaphrodite
of
a
one
having
body
female
or
having
position
of
a
gene
on
within
cytoplasm
of
cells;
a
reaction
assembled
to
make
the
spindle
chromosome.
in
which
a
covalent
bond
is
broken
during
luteal
by
phase
changes
that
occur
in
the
ovary
between
ovulation
and
interior
of
menstruation
in
of
division
cilia
and
also form
and agella.
the
mitosis
start
nuclear
the
water.
the type of nuclear division that
the
occurs in growth, asexual reproduction,
I
menstrual
cycle.
tissue repair and replacement of cells;
inbreeding
breeding
luteinising
between
hormone
(LH)
hormone
maintains the chromosome number in
individuals
of
identical,
or
secreted
very
by
anterior
pituitary
to
the daughter nuclei which are
similar,
inuence
genotypes.
activity
of
ovaries
and
genetically identical to each other and
independent
assortment
the
random
testes.
to the parent nucleus.
arrangement
of
the
alleles
of
two
or
mitotic
more
genes found
chromosomes
as
on
a
separate
result
of
M
occur
cell
formation
chromosomes
during
model
active
the
ratio
moulds
itself
to
at
site
actual
size
image
such
of
an
object
and
size
of
by
the
substrate
that
its
and
and
its
cytokinesis
an
of
match
as
drawing
two
cells.
or
the
photograph;
of
changes
cytokinesis
mitosis
monosaccharide
shape
the
between
between
into
enzyme
all
cell
meiosis.
dividing
induced t
a
pairing
magnication
of
cycle
within
during
compare
single
molecule
of
a
with
an
sugar,
e.g.
glucose
and fructose.
resolution.
enzyme-catalysed
reaction;
see
lock
morphological
male
and
key
pronucleus
the
nucleus
of
species
population
of
sperm
model.
organisms
inside
an
ovum
that
share
the
same
after fertilisation.
features,
such
as
morphology
181
Glossary
(outward
appearance),
behaviour
and
multicellular
many
cells,
mutagen
having
e.g.
agent
mutation,
chemical
mutation
e.g.
a
change
made
and
causes
and
to
body
of
organ
a
or
to
a
gene
more
group
to
a
somatic
diffusion
partially
water
different
DNA
major
organs
perform
of
potential
made
group
several
breeding
individuals
layer
of
opposite
with
of
through
see
a
down
water
genotypes;
changes that occur within
ovary
(owering
which
natural
selection
the
survival
contains
plant)
one
with
adapt
them
to
the
conditions
gametes
agent
(or
agents)
of
e.g.
and
and
have
and
a
greater
chance
passing
on
their
of
negative feedback
a
control
parameter
structure
or
a
the
hormone
blood
within
difference
carpel
ovules;
movement
cell
inside
cell
surface
placenta
a
is
maternal
gonad
a
set
kept
see
through
tissues for
attaches
a
drawing
organ
sizes
a
secondary
tissues;
plan
ovary;
occurs
menstrual
in
the
any
narrow
the
as
within
an
ovary
in
as
small
part
of
active
activity
plant
that
develops
into
a
the
cell
from
after fertilisation.
female
and
competitive
limits;
P
of
and
palindromic
that
cut
as
site
across
have
substance
an
site
of
plumule
restriction
DNA
at
sequences
these
of
the
same
on
direction
pentose
see
e.g.
inhibitor.
two
homologous
to
by
one
rarely
molecules
pairs
non-sister
sub-unit
a
(e.g.
in
in
bases
the
3′–5′
5-carbon
bond
amino
chromatids
grain
osmosis.
phosphate
(purine
or
molecule
and
of
a
a
of
survival
of
pentose
that
sugar
and
nitrogenous
the
wall
of
contents,
pyrimidine).
a
is
by
mitosis
male
by
obese
than
if
it
gamete
cell
be for
than
height
30
kg
(e.g.
a
tubular
e.g.
and
vas
of
and
has
a
BMI
site
in
of
an
a
which
has
to
many
to
move
to
move
to
surface
oocyte
gene
of
genes
e.g.
cancer
as
it
controls
cell
division;
see
proto-oncogene.
and
of
long
chain
nucleotides;
of
solid food)
the features
which
expression
between
the
into
by
of
are
and
the
many
a
to form
the
an
amino
182
acids
unbranched
(>
10)
chain.
cell
three
or
more
sets
of
cell
in
nuclei
of
an
polyploidy
the feature
often
result
and
used
controlled
maybe
used
the features
of
an
is
common
in
an
but
rare
in
animals.
of
a
complex
by
to
by
joining
of
the
refer
gene
monosaccharides
generally for
organism..
by
glycosidic
to
to form
a
branched
or
under
all
amylose.
completed at fertilisation in an oviduct.
RNA
interaction
genotype
environment;
study,
see
particles
unbranched
that starts in the ovary and is
molecule
embryo.
movement
bonds
the process of forming ova
the
height.
DNA.
many
oogenesis
grains
inuence
human
carbohydrate formed
causes
pollen
stigma.
membrane.
individual
to
grain
anther.
move
organism;
potential
that
in
organ
vesicle formed
phenotype
oestrogen.
gene
cell
to form four
pollen
an
polysaccharide
oncogene
nuclei.
diploid
transfer
anther
plants,
oestradiol
that
two
conditions.
muscle
deferens
oviduct
bacteria,
inside
m
sac;
plants)
-2
greater
nucleus
grains.
sac
chromosomes
should
spore
pollen
between
polyploidy
greater
a
to form
meiosis
polypeptide
considered
in
generative
mother
joined
20%
a
nutrients for
adverse
contraction
secondary
is
of
molecule,
bond
(owering
energy
phagocytosis
adult
embryo
same:
O
an
on
phenotype.
read
and
mass
effects
the
direction).
covalent
through
peristalsis
sperm
body
an
meiosis
composed
obesity
has
of
(microspore)
by
polynucleotide
base
water
acids.
perennation
storage
composed
of
same feature,
sugar,
away from
of
ribose.
peptide
two
of
identical.
acid,
cell
they
polygeny
nucleic
of
show
enzymes
sites;
from
nucleotide
not
plant.
pollination
are
of
loss
gene
shoot
formation
chromosomes;
do
complementary
polynucleotides
enzyme
and
enzyme;
chromatids
of
the
cytoplasm
due
vacuole
pollen
DNA
section
a
pollen
of
of
distribution
drawings
wall
pleiotropy
gamete.
divides
non-sister
and
showing
movement
membrane
a
pollen
reduces
and
of
body
value
point for
inhibitor
to
the
a
cells.
plasmolysis
cycle.
haploid
than
into
the
exchange
between fetal
relative
divides
other
by
blood.
an
contains
that
liquid
method
such
positive feedback.
non-competitive
of
vesicle formed
plan drawing
that
secretes
formed
possible;
of
membrane.
substances
pollen
parameter
bilayer
concentration
between
and
and
it
organ formed from fetal
owering
parameter
making
phospholipid
different features
of
hydrophilic
regions
a
is
alleles.
ovum
temperature
suitable for
has
to
that
of
seed
keeps
of
more
and
of
the
the
owering
that
attached
group
these
ovule
breeding
soluble;
of
phosphate
predators,
climate;
middle
individuals
base
or
progesterone.
release
oocyte from
competition
often
a
the
ovulation
environment,
acids,
by
oestrogen
an
composed
particular features
produces
that
in
of
(mammals) female
individuals
is
hydrophobic
maternal
the ovary during a menstrual cycle.
N
lipid
two fatty
which
water
bond
e.g.
RNA.
pinocytosis
between
different
inbreeding.
ovarian cycle
uterus.
covalent
nitrogen-containing
membrane
gradient;
bond
nucleotides,
membranes.
outbreeding
of
and
glycerol,
that
organ.
water
permeable
two
phospholipid
of
see
phosphodiester
between
to
potential.
mutation.
muscular
of
together
tissue.
together
osmosis
chromosome
a fungus
outer
or
see
system
work
hyphae.
myometrium
one
functions;
composed
work
major functions;
a
see
gene
that
perform
of
plants.
some
mutation)
mutation);
mycelium
the
body
radiation,
structure
tissues
compounds.
mutation
many
a
animals
that
(chromosome
(gene
organ
anatomy,
physiology.
chain,
e.g.
glycogen
and
Glossary
polyspermy
fertilisation
of
an
ovum
Q
by
more
ovum
than
one
usually fails
to
develop
if
this
happens.
same
at
group
species
the
same
of
living
leads
to
magnitude
of
happens
the
in
secretion
follicular
individuals
in
the
of
same
the
area
time.
positive feedback
system
qualitative
does
population
of
any
an
that
change
increase
change
effect
of
in
in
a
numerical
results,
refers
taking
the
end
phase
colour
and
of
of
the
menstrual
to
or
anything
which
recording
results,
to
the
e.g.
mass
and
that
cell
R
organism
that
of
an
embryo
of
and
DNA
DNA from
of
(e.g.
two
different
the
new
allelic
pairs
as
a
result
of
or
2
genes
the
result
between
of
endometrium
in
the
uterine
same
of
crossing
chromosomes
homologous
of
chromosomes
tightly);
nuclear
an
down
at
end
isolation
separation
of
method
to
pollination
in
which
are
unable
see
so
anthers
to
with
sympatric
classied
in
sometimes
in
microscopy
points
the
that
ability
are
on
do
method
not
stigmas
same
of
as
the
separate
of
a
points;
microscope
wavelength
light)
to
stigmas
of
pollen
stigma
or
within
between owers
on
uid
containing
sperm
seminal
and
vesicles
and
gland.
of
of
the
replication
DNA
by
using
existing
the
is
as
templates for
about
assembly
of
nucleotides;
molecule
of
DNA
each
new
radiation
is
one
‘old’
used.
as
polynucleotide
enzyme
enzyme
that
and
one
DNA
at
specic
one
of
many
base
tubules
also
‘new’.
cuts
cross-
sequences;
which
and
same
transfer
anther
polynucleotides
across
in
which
germinate
the
seminiferous tubule
pollination
to
in
to
kingdom
promote
A
plant.
production
restriction
to
→
close
protoctist.
method
e.g. Aa
cross-pollination
semi-conservative
two
and
written
allele,
populations.
ripen
(e.g.
Protoctista,
one
grains
prostate
half
protogyny
only
secretions from
resolution
organism
during
that
allopatric
protogyny.
protist
pair)
nuclei
interbreed
occurs
cross-
dichogamy
(allelic
haploid
that
prophase.
promote
ovum.
separation
a.
semen
together
stigmas;
organisms
condense
distinguish
before
contain
the
resolution
protandry
the
of
membrane
of
polar
an
exact
division
and
breaks
is rst
DNA.
successfully;
(coil
alleles
give
grains from
they
which
haploid
of
pair.
of
and
nuclear
cell
I
becomes
alleles
self-pollination
populations
in
of
to
same ower
of
larger
genotype.
production
reproductive
stage
implantation.
of
ovulation.
rst
so
to
over
cycle
copy
menstruation
state
unlinked
the
replication
prophase
pair
grow
the
a
meiosis
self-incompatibility
assortment
prokaryote.
between
a
pollen
of
uterine
1
see
of
the
ovulation
in
at
(smaller
meiosis
and
adjective from
growth
in
is
the
if fertilised
promote
phase
embryo
produced
in
after
combinations
eukaryote.
proliferative
phase
species)
membrane-
genes
the
together.
independent
prokaryotic
of
hydrocarbon
two
in
cells
e.g.bacteria;
an
segregation of
of
organelles,
with
any
plant.
recombination
nuclei
acid
a
translation.
has
the
occurs
oogenesis
root
joined
prokaryote
fatty
between
endometrium
body);
proteins
after
in
phase
that
accept
sources
RER
acid
bonds
atoms
secretory
cycle
modication
occur
and
double
secondary oocyte
recombinant
that
body
no
carbon
negative feedback.
processes
bound
saturated fatty
on
owering
without
which
recording
length.
oestrogen
at
post-translational
Golgi
e.g.
or
chain.
numerical
as
anything
taking
texture.
involves
the
to
involve
quantitative
LH
see
refers
not
radicle
cycle;
S
sperm; fertilised
known
as
in
the
testis
in
which
restriction
ripen
spermatogenesis
occurs.
endonuclease.
before
anthers;
see
dichogamy
and
sex
restriction
site
specic
sequence
chromosomes
bases
proto-oncogene
gene
which
in
DNA
become
an
usually
cut
across
products
of
oncogenes
are
pair
of
determine
known
as X
sex
and Y.
both
oncogene;
sex
polynucleotides;
that
restriction
can
enzymes
and
where
the
of
protandry.
mutate
chromosomes
see
linkage
genes
that
occur
on
the
palindromic
proteins
sex
chromosomes
are
sex-linked
as
site.
that
control
the
cell
cycle.
their
rhizome
protoplasm
contents
of
cell
cell
surface
membrane,
stem
which
acts
of
vegetative
determination
and Y
of
associated
with
of
sex
by
the X
reproduction
cytoplasm
sometimes
is
as
the
organ
and
and
horizontal
including
an
inheritance
perennation,
chromosomes;
in
mammals,
e.g.
nucleus.
the Y
chromosome
has few
genes
so
ginger.
purine
a
nitrogen-containing
sex
ribonucleic
compound
composed
of
two
by
carbon
and
of
nucleotides
and
RNA
compound
by
is
composed
of
one
part
carbon
component
of
and
of
ribosome;
RNA.
an
that form
on
the X
chromosome.
two
chromosome
centromere;
enzyme
identical
joined
copies
together
they
are
at
identical
peptidyl
made
catalysing formation
any
mutation
that
might
of
have
nitrogen;
nucleotides
loci
chromatids
apart from
is
to
RNA
ring
occurred
during
replication.
of
somatic
peptide
and
of
nitrogen-containing
rRNA for
DNA
form
a
the
transferase
formed
(rRNA)
RNA.
a
refers
rRNA.
of
which
pyrimidine
and
that form
ribosomal
DNA
tRNA
always
polynucleotide;
sister
mRNA,
almost
single
gene
short-lived
nitrogen;
see
component
(RNA)
rings
stranded,
formed
acid
linkage
cells
non-reproductive
(body)
bonds.
cells
e.g.
that
do
muscle
not
cells
give
and
rise
to
blood
gametes,
cells.
183
Glossary
somatic
gene therapy
insertion
an
testa
rise
test cross
of
seed
coat.
U
allele
to
into
a
cell
gametes;
inherited
somatic
that
inserted
by future
mutation
occurs
in
body
inherited;
speciation
species
see
idea
is
be
the
a
cells
and
molecule
has
a
in
seminiferous
in
sporangium.
reproductive
which
a
to
small
structure
in
tissue
fungi
plants;
and
structure
prokaryotes,
protists,
composed
of
may
longer
base,
but
similar
cells
culture
in
be
(or
all
different
of
RNA.
that
work
several)
identical
types;
a
growing
sterile
see
plant
assembly
of
nucleotides
template
polynucleotide
RNA
during
type
amino
of
a
and
one
or
several
nuclei
as
a
uterine
to
but
dispersal
and/or
survival
translation;
result
of
translation
in
acids
conditions.
body
made
of
Paramecium;
one
see
base,
a
component
DNA.
maternal
uterus
(and
blood ows
placenta)
in
this
artery.
uterine
cycle
within
the
a
animal
changes
uterus
to
see
uterine vein
mRNA
on
by
a
of
in
this
that
during
occur
a
menstrual
uterus
DNA.
that
(in
which
the
on
organism
different
(and
placenta)
during
the
organ
and fetus
nutrition
internal
and
in
develop
protection
development.
that
V
organism
the
differences
between
engineering.
assembly
ribosomes
mammals)
embryo
receiving
ribosomes
blood ows
uterus
anticodon.
an
genetic
maternal
the
vein.
of
using
(interspecic
variation)
and
amino
within
unfavourable
not
artery
the
species
for
a
pyrimidine
RNA
variation
cytoplasm
having
Amoeba,
away from
of
RNA
acids
transgenic organism
DNA from
or
medium.
production
has
of
e.g.
uracil
of
not
one
cell,
multicellular.
used.
a
cells
transcription
transfer
produces
reproductive
by
DNA
no
unicellular
cycle.
transfers
produced
note that the
now
perform
mixture
tissue
hypha
of
of
gene
organ.
of
spores.
spore
group
a
is
pyrimidine
functions;
or
process
vertical
plants
tissue
together
testis.
a
a
component
new
allopatric
concerned;
an
another that
recessive for the
backcross
thymine
mutation.
a
genes
term
an organism with
genotype with
homozygous
or
that
mating
unknown
is
not
which
see
the
that forms
and
cannot
or function.
sperm
in
sporangium
fungi
line
by
that
role
sporangiophore
fungi
and
germ
spermatogenesis
tubules
give
speciation.
particular
forming
allele
mutation
process
specicity
not
generations.
cells
is formed;
sympatric
will
species
(intraspecic
sequences
variation).
stabilising
selection
selection
of
in
codons
to
determine
the
sequence
vector
which
the
proportions
of
different
of
amino
acids
in
a
is
types
or forms
within
a
population
transmission
in
genetic
used
to
move
not
change from
generation
to
microscope
uses
an
electron
to
generation.
organ
in
view
thin
subcellular
a ower
sections
to
of lament
pollen
and
triglyceride
anther
of
sacs.
cells
animal
cells
which
retain
a
glycerol
triplet
a
ability
to
divide
by
mitosis
and
that
type
and
of
lipid
cells
which
group
of
three
mutation
plants
codes for
an
amino
of
by
increasing
articially
in
asexual
reproduction.
reproduction
acid;
asexual
DNA
in
plants
in
which
a
see
large
part
of
the
parent
plant
codon.
specialise.
repeat
are
acids.
bases
separates
stutter
vectors
composed
three fatty
fairly
produce
of
propagation
of
reproduction
the
vector
host
study
vegetative
stem
a
a
plasmids.
encouraging
with four
into
structures.
number
composed
examples
and
vegetative
male
gene
beam
viruses
stamen
a
electron
organism;
do
engineering
polypeptide.
triploid
a
refers
to
a
nucleus,
cell,
to
become
an
independent
tissue
individual.
sequence
of
bases
as
happens
in
the
or
organism
having
three
sets
of
vertical transmission
gene for
huntingtin
cause
Huntington’s
which
is
chromosomes;
the
see
parent
change to
DNA
trisomy
(or
more)
base
pairs
are
by
sexual
no
base
pairs
are
speciation
or
asexual
means
of
a
pathogen from
rather than two; Down’s syndrome is
lost.
mother
sympatric
also
three chromosomes of the same type
transmission
replaced;
offspring
condition in which there are
reproduction;
in which one
of
to
polyploidy.
disorder.
whether
substitution mutation
transfer
endosperm,
genes from
of
formation
to
child
before
or
during
caused by trisomy of chromosome 21.
of
birth.
new
species
population;
polyploidy
within
a
common
occurs;
trophoblast
single
in
see
plants
where
that forms
embryo
allopatric
the
speciation.
at
extra-embryonic
exchange
implantation
epithelium
of
tissue
surface for
the
and,
early
W
later,
chorionic
villi
water
in
T
the
tube
nucleus
controls
telophase
stage
at
end
of
potential
potential
energy
of
a
placenta.
haploid
the
growth
nucleus
of
the
solution
in
water;
is
comparison
to
pure
that
it
a
measure
of
the
ability
of
pollen
a
nuclear
solution
to
absorb
or
lose
water
tube.
division
in
which
and
chromosomes
tumour
uncoil
and
nuclear
suppressor
around
gene
a
protein
that
the
assembly
of
a
that
is
used
plant
during
replication
the
expand
plant
assembly follows
osmosis.
the
184
rules
of
base
is
turgid
when
pairing.
any further;
it
occurs
and
when
transcription;
cell
new:
cannot
polynucleotide
and
osmosis.
polynucleotide
turgid
for
applied
soil
inhibits
them.
mitosis.
template
is
cells
absorb
to
cells,
tissues,
organs
which
the
codes for
reforms
gene
membrane
water
by
the
atmosphere;
see
Index
Key terms
are
in
biochemistry
bold
biological
A
biuret
solution
bivalents
acrosomes
energy
49
smoking
63,
cilia
173
165
30
49
enzymes
active transport
in
48,
cells
cloning
165
process
144
49
codominance
blastula
165
budding,
reproduction
96
39
by
76,
144–5
codons
67
,
71
64
bulk transport
adventitious
roots
and
cells
cohesion
39
4,
5
146
collagen
agriculture, GMOs
in
16,
16–17
118–19
C
alanine
82–3
164
sites of
adenine
80–1,
84
chymotrypsin
19
cigarette
blastomeres
active
and
segregation
138
83
blastocyst
activation
meiosis
2
species
competitive
inhibitors
complementary
albinism
108
capacitation
alcohol
(during
84,
85,
pregnancy)
90,
92,
96,
173
capsule,
102–3
cell
32
carbohydrates
3,
reaction
speciation
138
carbon
acid
activation
12–13,
70–1
14,
carboxyhaemoglobin
66
carcinogens
173
166,
167
carpels
148,
48
catabolism
luteum
8,
9
catalase
8,
9
54,
catalysts
55,
2
bonds
cell
nuclear division
79,
83
2,
3,
membrane
30,
31,
32,
36–7
,
gland
128
38–9,
plants, GM
118,
division
91
eukaryotic
119
30–1,
32,
33,
36–7
,
68,
72,
12,
13,
151
functions
resistance
134,
135
microscopy
and
27
,
prokaryotic
32–3,
70,
71
and
tissues
and
organs
13
antiparallel
cellulose
polynucleotides
63
2,
centrioles
115
83
146
32,
76
34–5
cytosine
antigens
114,
79,
144
cytoplasm
anticodons
76,
28–9
cytokinin
135
(CF)
30
cytokinesis
antibiotics
67
144–5
cystic brosis
antibiotic
85
147
cysteine
modied
148,
153
(chromosomes)
76–83
cuttings
anthers
150,
cells
animals
genetically
120–1
76
crossing over
breeding
64
160
cross-pollination
aneuploidy
49,
48
crop
anaphase of
152
59
Cowper’s
anabolism
171
159
covalent
amylose
170,
2
cotyledons
amylopectin
159,
151
cortex
amylase
59
129
corpus
amnion
126–7
165
control variables
acids
124,
2
contraception
amino
6
6–9
continuous variation
allopatric
48
2
condensation
alleles
molecules
164
compounds
amino
57
12
63,
64
8
31,
78,
79,
83
D
articial
propagation
aseptic technique
asexual
atoms
147
147
reproduction
76,
cervix
144–7
CF
2
autosomal
recessive
autosomes
72,
conditions
conditions
92
109
108
146
chi-squared
112–13,
snails
2
dihybrid
solution
79,
82,
83,
85
diploid
72
116–17
survival
and
133
147
cell
crosses
membranes
38
98–101
151
76,
18,
cells
80
molecules
mutations
128,
128–9
directional
4
selection
137
20
90,
92
disaccharides
6,
7
144
crossing
tests
dipolar
127
chromosomes
biochemical
dioecy
DNA
140–1
curves
binary ssion
171
see
151
differentiation
diffusion
acid
63
mellitus
differential
33
36
chromosome
Benedict’s
diabetes
gonadotrophin
chromatin
bell-shaped
deoxyribose
104–7
31,
67
deoxyribonucleic
dichogamy
2,
132–3
code
135
chromatids
banded
2
166
chorionic
bacteria
degenerate
152
test
cholesterol
chorion
115
83
chloroplasts
B
Darwin, Charles
114,
elements
chlorophyll
buds
79
164
chemotropism
chiasmata
146
axillary
158,
72,
(cystic brosis)
chemical
autosomal dominant
auxin
centromere
over
85
discontinuous variation
124,
124–5
18–21
homologous
68,
72,
95
disruptive
selection
137
185
Index
disulphide
DNA
bonds
fertilisation
15
(deoxyribonucleic
breakage
and
genetic
engineering
protein
synthesis
replication
to
protein
dominant
90
brous
112–13
agella
30,
owers
and
uid
76
168,
169,
128–9
follicular
81,
148–51
syndrome
(FAS)
173
syndrome
168,
63,
guppies
during
pregnancy
hormone
phase of ovarian
64
H
(FSH)
cycle
groups
15,
fructose
16,
mutation
fruit
microscopes
26,
109
cells
80,
sac
embryo
sac
149,
150,
heterochromatin
97
,
98–9,
heterostyly
(follicle-stimulating
6
170
histograms
76
human
165,
166,
151
hormone)
hexoses
169,
72
100
149
168,
embryos
94–5,
151
cells
148
153
28–9
FSH
mother
82
6
fruit ies
embryo
131
129
hermaphrodites
electron
130,
145
haploid
E
16
170
haemophilia
frameshift
164
170
fragmentation
173
170
159,
141
haemoglobin
drugs,
169,
168
hormone
172–3
haem
Down’s
hormones
Graaan follicle
guanine
36
166–7
,
152
double fertilisation
(GnRH)
32
follicle-stimulating
103
168
gonadotrophin-releasing
reproduction
alcohol
foetus
95
epistasis
hormones
gonadotrophic
16
43
mosaic
foetal
72–3
cells
gonadal
164–5
proteins
accid
phenotype
alleles
dominant
and
62–3,
85
of
66–71
64–5,
to
acid)
exchange
152,
127
homologous
171
pairs of
chromosomes
G
plant
152,
endocrine
organs
endocytosis
168
39
endometrium
endosperm
68,
152–3
158,
166
endosymbiosis
6
gametes
80,
gene
33
enzyme-substrate
49,
50,
57
factors
48–9
in
generative
restriction
epididymis
epistasis
epithelial
activity
activity
56–9
50–5
112
cells
genetically
34,
plate
36
79,
117
,
83
90,
92,
102–3
116–17
Huntington’s
92,
hydrogen
93
regions
hydrophobic
50
bonds
germ
19
90,
72
line
cells
32,
34,
144–5
92,
cells
30–1,
32,
germ
line
gene therapy
germ
line
mutations
germinal
33,
36–7
,
72
epithelium
gestation
period
gibberellin
132,
134
glans
159,
149
melanism
39
variation
glucose
49
glycerol
84
90
169
160,
proteins
3,
6,
57
164
compounds
10,
2
16
116–17
8
interphase of
exopeptidases
cell
cycle
glycine
12,
8,
tubes
fat
diet
the
acids
10,
pronucleus
reproductive
period
186
6,
164
(genetically
modied
164
system
solution
18,
50
8
11
ionic
bonds
ions
2
2,
15
organisms)
118–21
island
158–9
Gogli
fertile
bonds
124
72
iodine
117
,
female
36,
11
GMOs
female
149
intraspecic variation
glycosidic
fatty
161
36
158
glycoproteins
in
cells
9
intine
glycolipids
Fallopian
124
16
interstitial
glycogen
83
11
interspecic variation
F
body
31,
99
134–5
158
insulin
exocytosis
134,
146
(penis)
globular
92,
48
161
inorganic
exine
36
115
inhibitors
evolution
15,
153
128
inhibin
68,
11,
assortment
model
inheritance
eukaryotic
36
80
inheritable
eukaryotes
64
124
industrial
euchromatin
11,
63,
7
I
induced t
ethanol
4,
90–109
genotypes
10
15,
interactions
independent
ester
109
(GMOs)
inbreeding
equilibration
4,
118–21
genetics
39,
66,
72
135
168–71
139
reaction
hydrophilic
organisms
158,
158–71
disorder
bonds
hydrolysis
112–21
76
modied
genes
146
reproduction
hybrids
101
stability
reproduction
insulin
human
66–7
ratios
human
plant
engineering
genetic
129
149
85,
diagrams
genetic
160
128,
114
84,
code
genetic
102–3
equatorial
genetic
95
hormones
162
162–3
nuclei
72–3,
genetic
inuencing
investigating
148,
mutations
genes
enzymes
92,
gene therapy
complexes
84,
horizontal transmission of
galatose
gametogenesis
152
72,
endemic
species
132
Index
isolating
isotopes
mechanisms
138,
monosaccharides
139
Morgan, Thomas
2
morphological
K
mRNA
Bernard
71,
7
Hunt
pedigree
94
species
(messenger
68–9,
Kettlewell,
6,
penis
138
RNA)
diagrams
(glans)
pentoses
62,
66,
67
,
117
peppered
pepsin
160,
6,
164
62
moths
49,
108–9
134–5,
140
59
140
multicellular organisms
multiple
alleles
34,
76–7
103
peptide
bonds
peptide
synthetase
12,
13
48
L
mutagens
lacunae
LH
mutation
165
(luteinising
hormone)
168,
169,
light
perennation
128–9,
mycelium
130–1
peristalsis
145
myometrium
170–1
ligase
129
pH
158
26–7
,
N
29
phosphatase
natural
10–11,
selection
132,
133,
124,
58–9
127
12
59
phosphodiester
48
3,
164
activity
90,
phenylalanine
microscopes
lipids
160,
enzyme
phenotypes
113
lipase
and
146
bonds
62,
68
134–7
,
phospholipids
19
10,
11,
36
140–1
loci of
chromosomes
placenta
92
negative feedback
lock
and
key
model
plan drawings
phase of ovarian
cycle
(during
pregnancy)
170
lysosomes
30,
inhibitors
35
hormones
plants
non-reducing
sugars
7
,
18–19
breeding
non-sister
chromatids
83,
GM
nuclear
division
76,
77
,
80,
91
85
M
crops
118,
nuclear
3
envelope
112–13
48
plasmolysis
malaria
nuclei,
130–1
cell
31,
pronucleus
nucleic
164
acids
3,
reproductive
system
nucleolus,
160–1
cell
sterility
(plants)
151
nucleotides
119–20
null
152
31
pollen
male
130
62–3
plumules
male
42–3
72
pleiotropy
male
146–51
31
plasmids
nucleases
26
120–1
82
reproduction
magnication
146
57
31
macromolecules
172
173
plant
non-competitive
171,
170
48
nicotine
luteal
(hormones)
166–7
,
62,
grains
81,
148–9,
150–1,
152,
64–5
153
medicine, GMOs
meiosis
80–1,
meiosis
I
meiosis
II
82,
in
117
,
82–3,
85,
hypothesis
nutrition,
162
104
maternal
pollen
mother
pollen
sacs
83
82,
134,
150–1,
153
O
83
polygeny
126
140
obesity
membrane,
148
148
pollination
melanism
cells
172
cell
30,
31,
32,
36–7
,
polymers
11
3
38–9,
oestradiol
158,
159,
170
oestrogen
158,
169,
171
polynucleotides
13,
62–3,
64,
66
76
Mendel, Gregor
90,
cycle
158,
cells
cycle
77
,
see
nuclear division
79,
plate
79,
168
128,
polyspermy
162
population
35
12,
67
,
30–1,
33,
compounds
8–9
124
positive feedback
36
(hormones)
post-translational
2
170
modication of
proteins
34–5
38,
product
66
43
molecules
50
9
outbreeding
microorganisms, GM
26–7
,
cycle
149,
79,
31,
158,
159
prokaryotic
cycle
158,
proliferative
164
164
149,
80,
150,
162,
152,
163
144
32–3
phase of
uterine
cycle
153
promotor
sequences
propagation,
plant
92,
118
147
77
nuclear division
78,
83
3
P
monohybrid
33,
170
prophase of
2,
32,
cells
82
ovum
cell
prokaryotes
170
153,
33
ovules
76–9,
171
83
ovulation
mitochondria
169,
28–9
oviducts
microtubules
153
158,
147
ovaries
microscopes
progesterone
119
ovarian
micropropagation
crosses
94–5,
prostate
gland
3,
8
160,
164
100
prosthetic
monomers
6,
164
71
osmosis
molecules
129
polysaccharides
83
organs
mitotic
164,
83
organic
mitosis
polyploidy
163,
systems
organelles
microbrils
158
2
metaphase of
methionine
66,
mRNA
organ
metaphase
62,
72–3
78
RNA
metabolism
68,
77
162,
oogenesis
messenger
16,
77
oocytes
meristems
14–15,
170
oncogenes
meristematic
12–13,
92
oestrus
menstrual
polypeptides
palindromic
sites
groups
15,
16
112
protandry
151
187
Index
proteases
48,
protein bres
protein
30,
synthesis
proteins
3,
protists
34
self-pollination
50
semen
semi-conservative
19,
seminal
76
square
purines
SER
77
151
protoplasm
Punnett
62,
vesicle
replication
160,
(smooth
chromosomes
sex
linkage
plants
sickle
Q
quantitative
18–19,
investigations
160,
161,
(genes)
transfer
RNA
reticulum)
31
transmission
trioses
triploid
130–1
79,
reticulum
(SER)
31
tRNA
66,
71
71
(chromosomes)
128
microscope
13
DNA
66,
67
nuclei
81,
152
128–9
(transfer
RNA)
62,
66,
70,
71
50–1
20–1,
somatic
gene therapy
somatic
mutations
trophoblast
115
165,
166,
171
52–3
speciation
trypsin
128
tube
138
49
nuclei
149
R
species
R
groups
radicles
rDNA
(amino
acids)
13,
15,
specicity of
49
sperm
152
(recombinant
recessive
alleles
recessive
sugars
82,
molecules
160,
161,
spermatogenesis
113
sporangiophores
95
epistasis
reducing
DNA)
tumour
138–9
sporangium
103
6,
spores
18
81,
162,
tunica
48
turgor
162
suppressor
albuginea
turgid
164
cells
DNA
64–5,
69,
72,
76
stabilising
161
pressure
43
145
U
148
selection
148,
starch
144–7
plants
starch
146–53
reproductive
isolation
stem
138–9
18,
21,
synthetase
cells
160,
(rough
endoplasmic
reticulum)
31
stigmas
uterine
artery
uterine
cycle
microscopes
restriction
enzymes
restriction
sites
26
170
77
166
151
158,
164
159
structural
112
166
48
uterus
resolution of
stroma
164
50–3
uterine vein
RER
10
8
tests for
158–71
acids
63
urethra
human
76
151
uracil
asexual
34,
136
unsaturated fatty
stamens
reproduction
77
43
145
145,
genes
unicellular organisms
replication of
genes
92
V
stutter
112
reverse transcriptase
rhizomes
ribose
rice,
substrates
146
subtilisin
31,
genetic
RNA
substitution
117
63
ribosomes
mutation
32,
66,
68,
modication
(ribonucleic
acid)
sucrase
71
sucrose
120–1
62–3,
66,
67
,
sugars
rough
endoplasmic
rRNA
(ribosomal
reticulum
RNA)
(RER)
31
49,
129,
51,
52,
130–1
56–7
48
158,
30
33
43
164
85,
deferens
vectors
18–19
unit
symbiosis
39,
variation
vas
6–7
,
6–7
,
vacuoles
vagina
48
sympatric
62
48,
49
Svedberg
68
129
mutation
13,
124–7
,
160,
(genetic
140–1
164
engineering)
vegetative
propagation
vegetative
reproduction
vertical transmission of
speciation
138,
138–9
vesicles
vulva
146–7
genes
39
158
W
saturated fatty
SCID
(severe
acids
temperature
combined
immunodeciency
scrotum
telophase of
10
syndrome)
114
templates
test
160
secondary oocytes
secretory
phase of
seed
153
82,
158,
uterine
163,
cycle
and
testa
170
testerone
enzymes
79,
57
(polynucleotides)
crosses
164
nuclear division
64
83
water
4–5
water
potential
segregation of
testes
alleles
self-incompatibility
188
84,
151
85,
92,
95
153
Z
160,
160,
thymine
tissue
40–3
95
161,
169
zygotes
coat
38–9,
161,
63,
164
64
culture
147
76,
80,
84,
112
147
T
S
28
10
endosperm
trisomies
83
mRNA
70,
113
6
triplets,
148–53
endoplasmic
68–9
66,
electron
triglycerides
97
72,
66,
62,
translocation
tripeptides
anaemia
DNA
(tRNA)
translation of
162
72
chromatids
smooth
investigations
34
transgenic organisms
158–71
cell
sister
65
reproduction
human
62
64,
164
endoplasmic
sex
sexual
95
114
pyrimidines
qualitative
164
seminiferous tubules
proto-oncogenes
protogyny
36
tissues
153
transcription of
31
66–71
12–17
,
160,
150,
164–5
135
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