Unit Two: Multicellular
Organisms
Cells, tissues and organs
Cells, tissues and organs
LI: 1. Explain what is meant by the term
“specialisation of cells”
2. Give details of how the structure of an
animal cell or plant cell can relate to its
function.
3. Describe the levels of organisation
found in animals and plants.
National 4/5 Biology Course Unit 2
Specialisation in animal cells
Cells in plants and animals show
specialisation. This means they have a
special shape or structure that allows
them to carry out a specific function.
National 4/5 Biology Course Unit 2
Levels of organisation in animals
Cells
Tissues
Organs
Organism
National 4/5 Biology Course Unit 2
Activity
For the cardiovascular system and the
nervous system. Find out:
1. Function of the system
2. The organs in the system.
3. The cells in the system.
4. For each cell describe what is special
about its shape that allows it to do the
job it does.
National 4/5 Biology Course Unit 2
Specialisation in plant cells
Cells in plant also so specialisation.
e.g. root hair cells
Have large projections
from each cell which
increase the surface
area for absorbing
water
National 4/5 Biology Course Unit 2
Phloem cells transport
food in plants. The end
walls of phloem cells
are like a sieve, which
allows glucose to move
from one cell to the
next.
National 4/5 Biology Course Unit 2
Stomata are pores on
the bottom of plant
leaves. These are made
of a pair guard cells
which change shape to
open and close.
National 4/5 Biology Course Unit 2
Stem cells and meristems
Stem cells
LI:
1. State that stem cells have the ability
to divide to produce cells that can
become different types of cells.
2. State that stem cells are involved in
growth and repair.
National 4/5 Biology Course Unit 2
Stem cells
Stem cells are found in animals. They are
cells which can divide by mitosis to
develop into specialised cells.
Stem cells are found in early embryos –
embryonic stem cells – and in adults –
adult stem cells.
National 4/5 Biology Course Unit 2
Embryonic stem cells
Found only in early
embryos.
Can develop into
any type of cell.
Allow us to grow
from tiny
embryo to a fully
formed baby.
National 4/5 Biology Course Unit 2
Adult stem cells
Found throughout
the body in adults
and children.
Use mainly for
repair. They
cannot form as
many specialised
cells.
National 4/5 Biology Course Unit 2
Medical uses of stem cells
Source of stem
cell
Medical use
National 4/5 Biology Course Unit 2
Use page
121 to
complete
this
table
Stem cell controversy
Carry out some research into the issues
surrounding stem cell research (scibrbrain)
Write a short essay:
Introduction – introduce the issue.
Arguments for – give 2 or 3 arguments in
favour of using stem cells from embryos.
Arguments against – give 2 or 3 arguments
against using stem cells from embryos.
Conclusion – what is your opinion?
National 4/5 Biology Course Unit 2
Meristems
LI:
1. Describe the role of meristems in
plants.
2. State that non-specialised cells can
become any type of plant cell and they
contribute to growth.
National 4/5 Biology Course Unit 2
Meristems
In animals, growth can occur any where in
the body.
In plants, however, growth is restricted
to special points called meristems.
National 4/5 Biology Course Unit 2
Apical meristems can
be found at the tip
of the root and tip
of the shoot. These
contribute to
increasing the length
of the plant.
Lateral meristems are
found in the stem
and make the stem
thicker.
National 4/5 Biology Course Unit 2
Control and Communication
The brain
LI:
1. Describe the structure of the brain.
2. Give details of the functions of the
different structures of the brain.
National 4/5 Biology Course Unit 2
Twig videos
Neurons as cells
Neurons as networks
National 4/5 Biology Course Unit 2
The brain
National 4/5 Biology Course Unit 2
Part of the brain
Function
Cerebrum
Enables conscious
thought and memory
Cerebellum
Controls co-ordination
and balance
Medulla
Controls breathing and
heart rate
National 4/5 Biology Course Unit 2
The nervous system
LI:
1. Describe the structure and function of
the central nervous system (CNS).
2. Describe the role of sensory and motor
neurons.
3. Describe the different responses
brought about by the CNS.
National 4/5 Biology Course Unit 2
Nervous system
The nervous system
is comprised of:
1. Peripheral
nervous system
2. Central nervous
system (CNS).
The CNS is made of
the brain and the
spinal cord.
National 4/5 Biology Course Unit 2
Gathering information
The sense organs collect information from the
environment.
Receptor cells are present in the sense
organs which detect stimuli (changes in
conditions).
This information is transmitted to the
CNS through sensory neurons.
National 4/5 Biology Course Unit 2
Responding to information
The CNS processes the information and
decides on what response to make.
The responses travel along a motor
neuron to effectors e.g. muscles or
glands.
National 4/5 Biology Course Unit 2
Stimuli
Senses
Sensory Neuron
CNS
Motor neuron
Effector
Response
National 4/5 Biology Course Unit 2
Effectors
Different effectors bring about different
responses.
e.g. A muscle will bring about a fast
response.
A gland will bring about a slower response.
National 4/5 Biology Course Unit 2
Reflex actions and reflex arcs
LI:
1. Explain what a reflex action is and give
some examples.
2. Explain the role of sensory, motor and
relay neurons in a reflex arc.
3. State that electrical impulses move
along neurones.
4. Explain the importance of synapses in
the nervous system.
National 4/5 Biology Course Unit 2
Reflex actions
Read page 130 and 131 on “Reflex
actions”. Make a short set of notes
explaining what Reflex actions are.
Include a description of at least 3 reflex
actions and explain what the (a) stimulus
is, (b) the effect, and (c) the advantage.
National 4/5 Biology Course Unit 2
Reflex arc
Reflex actions do not require conscious
thought.
If you touch something painful, the
receptors in the skin send an electrical
impulse along the sensory neuron to a
relay neuron. This passes the signal to a
motor neuron and onto the effector.
National 4/5 Biology Course Unit 2
National 4/5 Biology Course Unit 2
Stimuli
Senses
Sensory Neuron
RELAY NEURON
Motor neuron
Effector
Response
By not
involving the
conscious
brain the
reflex is quick
and prevents a
greater injury
from
occurring.
National 4/5 Biology Course Unit 2
Synapses
Neurons do not
directly touch
each other.
Between two
neurons there is a
tiny gap called a
synapse.
Signals move from
one neuron to
another by
chemicals called
neurotransmitters
.
National 4/5 Biology Course Unit 2
Hormones
LI:
1. State the function of the endocrine
glands.
2. Describe the role of hormones in
signalling.
National 4/5 Biology Course Unit 2
Hormones
Hormones twig video
Multicellular organisms using chemical
messengers, called hormones, to send
messages from one part of the body to
another.
Hormones are produced by endocrine
glands, all round the body, and travel in
the blood to their target tissue.
National 4/5 Biology Course Unit 2
Hormones are specific to their
target tissue.
Target tissues have
special receptors in
their cell membrane
which will recognise
specific hormones.
So a hormone will only
work on their target
tissue (similar to
enzymes).
National 4/5 Biology Course Unit 2
Endocrine glands
Task: Using the
internet, find
examples of a
hormone produced by
each of these glands.
Complete this table:
Gland
Hormone
Target
tissue
Role in the body
National 4/5 Biology Course Unit 2
Controlling blood sugar levels
LI:
1. Describe the role of the liver,
pancreas, insulin and glucagon in
controlling blood glucose levels.
2. Describe the causes and treatment of
type 1 and type 2 diabetes.
3. Explain the importance of controlling
blood glucose levels.
National 4/5 Biology Course Unit 2
Hormones in action: Blood glucose
levels
Glucose is essential in animals as a source
of energy. Cells in the body require a
constant supply of glucose for
respiration to occur.
Glucose is transported around the body in
the blood and its levels must be tightly
controlled.
National 4/5 Biology Course Unit 2
After a meal
1. After eating blood sugar levels
increase.
2. This is detected by cells in the
pancreas.
3. The pancreas releases a hormone
called insulin into the blood.
4. The insulin then travels to the liver.
5. This activates enzymes in the liver
which convert glucose into glycogen.
National 4/5 Biology Course Unit 2
5. The glycogen acts as a carbohydrate
store and this brings the blood glucose
levels down to the normal set point.
National 4/5 Biology Course Unit 2
In between meals
1. In between meals blood glucose levels
decrease as it is used up for
respiration.
2. This is detected by cells in the
pancreas.
3. The pancreas releases a hormone
called glucagon. (= “glucose gone”)
National 4/5 Biology Course Unit 2
4. The glucagon travels to the liver.
5. It activates enzymes in the liver which
convert the glycogen back to glucose.
6. This raises the blood glucose levels to
their normal set point.
National 4/5 Biology Course Unit 2
In summary…
National 4/5 Biology Course Unit 2
Carry out Activity 2.3.17 to help you learn
the steps involved in controlling blood
glucose levels.
National 4/5 Biology Course Unit 2
Diabetes
Nearly a ¼ million people in Scotland
suffer from diabetes.
This is a condition that affects the body’s
ability to control blood glucose levels.
There are two types of this condition:
Type 1 and Type 2
National 4/5 Biology Course Unit 2
Type 1 and Type 2 diabetes
Use in the
information on page
140 to complete this
table.
Type 1
diabetes
Type 2
diabetes
Cause
Treatment
National 4/5 Biology Course Unit 2
Importance of controlling blood
glucose
High blood glucose levels, caused by type
1 and type 2 diabetes, can cause damage
to blood vessels – especially those in
the eyes and kidney. This can lead to
damaged vision and kidney failure.
Polyuria (frequent urination), and blurry
vision are also symptoms of undiagnosed
diabetes.
National 4/5 Biology Course Unit 2
Reproduction
Reproduction in animals
LI:
1. Describe the chromosome complement
of the gametes and the zygote.
2. Give details of the male and female
reproductive structures, including
their function.
3. Describe the process of fertilisation
in animals.
National 4/5 Biology Course Unit 2
Sexual reproduction
Sexual reproduction involves combining
the genetic information of two
individuals.
The offspring produced by sexual
reproduction are similar to their
parents by not identical.
National 4/5 Biology Course Unit 2
Chromosome complement
The number of
chromosomes in a
cell is called the
chromosome
complement.
In humans this is 46
chromosomes.
National 4/5 Biology Course Unit 2
Different
numbers of
organisms have
different
numbers of
chromosomes.
Research the
following
organisms and
complete the
table.
Organism Number of
chromosomes
Dog
Human
Donkey
Elephant
Rabbit
Snail
Cabbage
National 4/5 Biology Course Unit 2
Organism
Dog
Human
Donkey
Elephant
Rabbit
Snail
Cabbage
Number of
chromosomes
38
46
62
56
44
24
18
National 4/5 Biology Course Unit 2
Diploid and haploid cells
Every cell in your body as two copies of
each chromosome (two sets of
chromosomes). They are described as
being diploid cells.
Gametes (sex cells) are described as
haploid because they have only one set
of chromosomes.
National 4/5 Biology Course Unit 2
National 4/5 Biology Course Unit 2
Gametes
• Sex cells are known as gametes.
• The gametes in animals are the sperm
and the egg
nucleus
Tail
cytoplasm
National 4/5 Biology Course Unit 2
Cell
membrane
Where are
sperm
made?
Sperm are
made in the
testes
National 4/5 Biology Course Unit 2
Where are
eggs made?
Eggs are
made in the
ovary
National 4/5 Biology Course Unit 2
• Collect the diagrams of the male and
female reproductive organs.
• Highlight the parts where gamete
production takes place.
National 4/5 Biology Course Unit 2
Fertilisation
Fertilisation is the fusion of the male
gamete nucleus with the female
gamete nucleus forming a zygote.
Sexual reproduction summary video
National 4/5 Biology Course Unit 2
Internal v. External fertilisation
In order for fertilisation to occur the
sperm require a liquid environment.
In many aquatic animals e.g. fish, frogs,
fertilisation occurs outside the body.
The offspring then develop outside the
body.
In humans, and other land animals,
fertilisation occurs inside the body.
National 4/5 Biology Course Unit 2
Reproduction in plants
LI:
1. Name the sex cells found in plants and
where they are made.
2. Describe the reproductive structures
of plants and give their function.
3. Describe the process of fertilisation
in plants.
National 4/5 Biology Course Unit 2
Gametes in plants
In plants the male gamete is pollen and
the female gamete is the ovule.
The reproductive organs of plants are
located in the flower.
Pollen is produced by the anther.
The ovule is produced by the ovary.
National 4/5 Biology Course Unit 2
Label the
diagram of
the flower
National 4/5 Biology Course Unit 2
Pollination
Pollination is the transfer of pollen from
the anther of one plant to the stamen
of the other.
National 4/5 Biology Course Unit 2
Pollination can be
caused by the wind or
by insects.
Insect pollinated plants
have flowers to attract
insects.
While wind pollinated
plants have anthers
and stigma that hand
outside the plant to
catch the wind.
National 4/5
Biology Course Unit 2
Fertilisation
In order for fertilisation to take place,
the pollen must reach the ovule nucleus.
To do this the pollen grows a pollen tube:
National 4/5 Biology Course Unit 2
Haploid
Ovule
nucleus
Haploid
Pollen
nucleus
The pollen lands on the
stigma.
It begins to grow a
pollen tube towards
the ovary.
The haploid pollen
nucleus then fuses
with the haploid
ovule nucleus to
form a diploid
zygote.
National 4/5 Biology Course Unit 2
Variation and Inheritance
Variation
LI:
1. Give some examples of variation with
in a species
2. Describe how sexual reproduction
maintains variation.
3. Explain the difference between
discrete and continuous variation.
4. Explain the difference between
polygenic and single gene traits and
give examples of each.
National 4/5 Biology Course Unit 2
Variation
National 4/5 Biology Course Unit 2
No two people are exactly alike. These
differences are called variation.
We are all different because we inherited
different genes from our parents.
Variation occurs in all animal and plant
species.
National 4/5 Biology Course Unit 2
Examples of variation
Following a class discussion: List some
examples of variation
National 4/5 Biology Course Unit 2
Discrete variation
Discrete variation refers to differences in
characteristics that have a defined
form.
You can think of it as being either/or.
(e.g. Your earlobes are either attached
or they are not. You can either roll your
tongue or you cannot You either have
brown hair or you do not).
Information is usually presented in a bar
graph or pie chart.
National 4/5 Biology Course Unit 2
Activity 1 – as a class find out the number of people with
each eye colour. Construct a bar graph of the results and
answer the questions.
Eye colour
Number of people
Blue
Brown
Green
Grey
1. What percentage of people have blue eyes?
2. What is the ratio of brown eyes to grey eyes?
National 4/5 Biology Course Unit 2
3. Write down 5 examples of discrete variation.
Continuous variation
Continuous variation exists in a range of
forms.
There are usually a variety of figures for
the characteristic.
e.g. Height and temperature.
Information is usually presented in a line
graph or histogram.
National 4/5 Biology Course Unit 2
Activity 2 – construct your own histogram using
the heights from the people in your class
Height (cm)
120 -124
Number of people
125-129
130-135
135-139
140-144
145-149
150-154
155-159
160-164
National 4/5 Biology Course Unit 2
Polygenic v. single gene traits
Characteristics showing discrete variation
are controlled by single genes.
e.g. tongue rolling ability, ABO blood
groups.
Characteristics showing continuous
variation are controlled by many genes
working together. Known as polygenic.
e.g. Skin colour, height
National 4/5 Biology Course Unit 2
Inheritance
LI:
1. Identify examples of dominant or
recessive traits.
2. Explain what is meant by “phenotype”
and give some examples.
3. Explain what is meant by “genotype”
4. Explain what is meant by “homozygous”
and “heterozygous”.
5. Use Punnett squares to predict the
inheritance of genes.
National 4/5 Biology Course Unit 2
Chromosomes
Genetic information passed on from
parents to offspring is carried on
structures called chromosomes which are
found in the nucleus.
National 4/5 Biology Course Unit 2
Genes and alleles
Genes are part of chromosomes.
Each gene can exist in a number of
different forms.
e.g. the gene for eye colour can be for
brown or blue or green or grey etc.
The different forms of each gene are
known as ALLELES.
National 4/5 Biology Course Unit 2
Collect a copy
of the diagram
and add it to
your notes
National 4/5 Biology Course Unit 2
Organism
Gene
Human
Blood group
Examples of
Alleles
A and B etc
Labrador Dog
Coat Colour
Black, Golden
Cat
Hair Length
Short, Long
Budgerigar
Feather Colour
Blue, Green
Cattle
Horns
Horns, Hornless
Pea Plant
Height
Tall, Dwarf
Maize
Grain Colour
Yellow, Purple
National 4/5 Biology Course Unit 2
Genotype and phenotype
The type of genes that an organism
possesses is called its GENOTYPE.
The appearance of the organism is
called is PHENOTYPE.
National 4/5 Biology Course Unit 2
Examples of phenotypes
Organism
Characteristic
Body Colour
Fruit Fly
Wing Type
Hair Colour
Guinea Pig
Hair Type
Stem Length
Peas
Phenotype
Grey
Black
Straight
Curled
White
Black
Smooth
Rough
Dwarf
Tall
Flower Colour
Red
White
National 4/5 Biology Course Unit 2
Dominant and recessive
Some phenotypes are dominant to others.
It is these characteristics you see even if
others are present
e.g. black hair is dominant to red hair.
+
=
The characteristic you do not see e.g.
red hair would be called recessive.
National 4/5 Biology Course Unit 2
True-breeding
A true-breeding organism can be crossed
with another organism of the same kind
and produce off-spring with exactly the
same characteristic phenotypes.
+
=
True breeding individuals have only one
type of allele
National 4/5 Biology Course Unit 2
A homozygous individual possesses
two of the same kinds of alleles e.g.
TT or tt (true breeding)
A heterozygous individual
possesses two different alleles
e.g. Tt
National 4/5 Biology Course Unit 2
The monohybrid cross
A cross between two parents different in
their phenotypes for one characteristic
is called a monohybrid cross.
We use the following symbols in a cross.
P
F1
F2
Represents the parents
Represents the first generation
Represents the second generation
National 4/5 Biology Course Unit 2
A lot of important work in genetics has been
done by studying inheritance in fruit flies.
National 4/5 Biology Course Unit 2
One characteristic which can be used to
illustrate inheritance is wing type in Fruit
Flies.
These can be NORMAL or VESTIGIAL.
Normal wings
National 4/5 Biology Course Unit 2
Fruit fly with
normal wings
Fruit fly with
vestigial wings
National 4/5 Biology Course Unit 2
Wing type is controlled by a pair of genes.
Each gene can be one of two types of
ALLELES.
N = normal wings
n = vestigial wings
Normal wing is dominant over vestigial
wing.
Vestigial wing is said to be recessive.
National 4/5 Biology Course Unit 2
Parent (P)
Gametes
F1 generation
NN X nn
N
All
Genotype all Nn
n
Nn
Phenotype all Normal winged
National 4/5 Biology Course Unit 2
Nn X Nn
F1
generation
Gametes
N or n
We can work out
the chances of each
type of offspring
using a punnett
square.
N or n
N n
N NN Nn
n Nn nn
National 4/5 Biology Course Unit 2
F2
Generation
N n
N NN
Nn
Normal Normal
n Normal
Nn nn
Vestigial
Genotypes
Phenotypes
NN , Nn and nn
Normal and Vestigial
Phenotype Ratio
3:1
National 4/5 Biology Course Unit 2
Complete the monohybrid cross
worksheet.
National 4/5 Biology Course Unit 2
Observed v. expected ratios
Monohybrid crosses always produce a 3:1
ratio in the F2 generation. However,
there is often a difference between the
observed and predicted figures.
This happens because fertilisation is a
random process involving chance.
National 4/5 Biology Course Unit 2
Pedigree charts and counselling
LI:
1. Understand the use of pedigree charts
to investigate the inheritance of a
characteristic.
2. Describe the importance of genetic
counselling.
National 4/5 Biology Course Unit 2
Pedigree charts
A pedigree chart is a type of family tree
diagram.
Activity:
Produce you own
Family tree.
National 4/5 Biology Course Unit 2
Pedigree charts are used to show the
inheritance of a particular
characteristic through generations of
the same family.
Males are represented with squares.
Females are represented with circle.
These can be coloured or blank depending
on whether or not you have the
characteristic.
National 4/5 Biology Course Unit 2
Male
Affected
-
Female
Unaffected -
shaded
unshaded
National 4/5 Biology Course Unit 2
• Imagine this was a
family tree for
colour blindness.
• An affected
individual has the
genotype bb and a
normal individual has
the genotype BB.
• Work out the
genotypes and
phenotypes for the
members of the
family.
National 4/5 Biology Course Unit 2
Genetic counselling
Some diseases are inherited. If a person
has a family history of disease they may
want to know what risk they have of
passing it on to their children.
Doctors can help people identify if they
are at risk and advise them on how to
minimise their risks of passing the
condition on – this is called genetic
counselling.
National 4/5 Biology Course Unit 2
Passing on conditions
People who are healthy
but carry genes for
a condition are
called carriers.
If two carriers have
children, they could
be affected,
unaffected or be
carriers.
National 4/5 Biology Course Unit 2
Activity
Imagine you are a genetic councillor.
Complete activity 2.5.10 on page 173.
National 4/5 Biology Course Unit 2
The need for transport
Transport in plants
LI:
1. Explain the need for transport systems in
plants
2. Name the different types of cell in the leaf
and state their function.
3. Give details of the structure and function of
xylem.
4. Describe the structure and function of the
stomata.
5. Describe the structure and function of
phloem cells.
6. Explain what is meant by “transpiration” and
give details of the flow of water through a
plant.
National 4/5 Biology Course Unit 2
The leaf
Collect
and
label
this
diagram
National 4/5 Biology Course Unit 2
Use page 177, to remind you of the roles
of the parts of the leaf. Complete this
table.
Section of the leaf
Waxy cuticle
Upper epidermis
Palisade mesophyll
Spongy mesophyll
Leaf vein
Lower epidermis
Guard cells
Function
National 4/5 Biology Course Unit 2
Importance of transport systems
Plants need transport systems to supply
the raw materials for photosynthesis
and to remove the products.
Xylem
Carbon
dioxide
Phloem
Light
Water
Glucose
Chlorophyll
Diffuse through stomata
National 4/5 Biology Course Unit 2
Oxygen
Xylem
The role of the xylem is to transport
water from the roots to all other areas
of the plant.
The xylem plays an important role in the
transport of minerals which are
dissolved in the water.
It also helps strengthen the stem of the
plant.
National 4/5 Biology Course Unit 2
The xylem is a hollow tube
of dead cells.
The xylem is
strengthened by rings
of lignin.
Water moves in an
upwards direction from
the roots.
National 4/5 Biology Course Unit 2
Stomata
Use nail varnish and sellotape to remove
look at stomata on the bottom of a leaf.
Your teacher will show you how. Draw
what you can see under the microscope.
National 4/5 Biology Course Unit 2
Stomata are pores on
the surface of leaves.
Stomata allow carbon
dioxide and oxygen to
enter/exit the leaf.
They also allow water
vapour to leave the
leaf by evaporation.
National 4/5 Biology Course Unit 2
Stomata made from two guard cells.
Water is pumped into or out of the cells
to open or close them.
Dark
Little water supply
Light
Good water
supply
Closing helps
prevent water
loss.
National 4/5 Biology Course Unit 2
Phloem
As well as transporting water and
minerals, plants have to transport the
sugar from photosynthesis from the
leaves to other parts of the plant.
This is carried out by special cells called
phloem.
National 4/5 Biology Course Unit 2
The phloem are
living cells.
Phloem cells are
connected by
sieve plates.
Have a companion
cell.
National 4/5 Biology Course Unit 2
Transpiration
Watch this clip http://youtu.be/w6f2BiFiXiM
Water travels up from the roots in the
xylem to the leaves. In the leaves it
moves by osmosis from cell to cell and
then evaporates into the gaps in the
spongy mesophyll cells.
If the stomata are open the water vapour
will diffuse out of the leaf. This is
called transpiration.
National 4/5 Biology Course Unit 2
Photosynthesis
produces sugar in
the leaves
Transpiration -water
evaporates from leaves
Sugar is transported in
phloem
stem
roots
The movement of water
through the plant is called
the transpiration stream
Water and ions pass
up xylem
Mineral ions enter by
Water enters
National 4/5 Biology Courseroots
Unit 2by osmosis
active transport
Transport in animals: Blood
LI:
1. Give examples of substances which are
transported in the blood.
2. Give the function of red blood cells,
including the role of haemoglobin.
3. Describe how the structure of red
blood cells is related to its function.
National 4/5 Biology Course Unit 2
Blood
Blood is crucially important to the survival
of the human body.
Each adult has 5 litres of blood in their
body – which transports useful
chemicals around the body: Oxygen,
carbon dioxide, urea, glucose, hormones,
antibodies etc.
National 4/5 Biology Course Unit 2
Blood is mostly water, with cells and other
substances suspended in it.
Red blood
cells
White blood
cells
Platelets
Plasma
National 4/5 Biology Course Unit 2
Research task
Use the www.blood.co.uk website to find
out the roles of the different
components in blood.
Find out the difference between the
blood groups.
National 4/5 Biology Course Unit 2
Red blood cells Red blood cells are
adapted to carry out
their function.
They have a biconcave
shape which
increases their
surface area –
allowing them to pick
up oxygen by
diffusion much
faster.
National 4/5 Biology Course Unit 2
RBCs - haemoglobin
RBCs contain a protein called haemoglobin.
In the lungs
oxygen is attached
Haemoglobin
Oxy-haemoglobin
In cells doing respiration
oxygen is released
National 4/5 Biology Course Unit 2
Transport in animals: Blood vessels
and the heart
LI:
1. Describe the structure of arteries,
veins and capillaries.
2. Identify and name the 4 chambers of
the heart.
3. Identify and name the major blood
vessels leading into and out of the
heart.
4. State the role of the coronary arteries.
5. Describe the pathway of blood through
the heart,
lungs
and body.
National
4/5 Biology
Course Unit 2
Blood vessels
There are three types of blood vessels.
blood from the
heart
Arteries
carry blood
away from
the heart
blood to the
heart
Capillaries carry
blood to and from
the body’s cells
National 4/5 Biology Course Unit 2
Veins
carry
blood back
into the
heart
Arteries
 thick muscular wall
 narrow central channel
 carry blood under high
pressure
National 4/5 Biology Course Unit 2
Capillaries
 form networks at
organs and tissues
 thin walled - only one
cell thick
 large surface area
allowing exchange of
materials
National 4/5 Biology Course Unit 2
Veins
 thin wall
 wide central channel
 carry blood under low
pressure
 contain valves which
prevent the backflow
of blood
National 4/5 Biology Course Unit 2
Valves
backflow
prevented
vein
valve
open
vein
valve
closed
blood to
the
heart
The valves allow blood to
flow in the correct
direction…
…but close if blood
starts to flow in the
wrong direction.
National 4/5 Biology Course Unit 2
The heart
The four chambers of the heart have
special names:
right
atrium
right
ventricle
left
atrium
left
ventricle
Collect the heart diagram and label the 4
chambers. National
Colour it4/5
in using
colour
Biologythis
Course
Unitscheme.
2
Pulmonary
artery
Aorta
Pulmonary
vein
Vena
cava
National 4/5 Biology Course
Label these
vessels on your
Unit 2
diagram
Coronary arteries
The heart is like any
other muscle – its
needs its own supply
of blood with oxygen
and glucose for
respiration.
These are supplied by
the coronary
arteries.
National 4/5 Biology Course Unit 2
Circulation of blood through the
heart
Blood high in oxygen is called oxygenated
blood
Oxygenated blood returns from the lungs…
pulmonary
vein
•in the _______
______
left atrium
•enters the ____
_______
left________
ventricle
•into the ___
aorta
•out through the _____
body
•to the ____
National 4/5 Biology Course Unit 2
Blood low in oxygen is called deoxygenated
blood.
Deoxygenated blood returns from the body
tissues…
vena_____
cava
•in the ____
right_______
atrium
•enters the ____
right ________
ventricle
•into the _____
pulmonary artery
•out through the _________
______
lungs where it picks up oxygen
•to the _____
National 4/5 Biology Course Unit 2
Heart and lung dissection
Transport in animals: The lungs
LI:
1. Explain the importance of rings of
cartilage in the airways.
2. Describe the process of gas exchange
and state where it takes place.
3. Explain how alveoli allow efficient gas
exchange.
4. Describe the role of the cilia and
mucus in protecting the lungs from
infection.
National 4/5 Biology Course Unit 2
The lungs
Collect
and
label
this
diagram
Ribs
National 4/5 Biology Course Unit 2
Diaphragm
Air enters the breathing system through
the mouth and nose. It then travels
down the trachea to the lungs.
The trachea is lined
with rings of
cartilage. This
provides strength
and prevents the
trachea collapsing
during breathing.
National 4/5 Biology Course Unit 2
Alveoli
At the end of the bronchioles are the
alveoli. These are the site of gas
exchange.
Bronchiole
Alveolus
Capillary
National 4/5 Biology Course Unit 2
Gas exchange
bronchiole
single celled wall
of alveolus
O2
layer of fluid
CO2
single celled wall
of capillary
red blood cell
National 4/5 Biology Course Unit 2
Gas exchange
Oxygen diffuses from an area of high
concentration inside the lung to an area
of low concentration in the red blood
cells.
Carbon dioxide diffuses from an area of
high concentration in the blood to an
area of low concentration in the lung.
National 4/5 Biology Course Unit 2
Efficient gas exchange
Alveoli are adapted for efficient gas
exchange in several ways:
Read page 202 of textbook.
Complete the following table. Think about and
discuss what the “advantage” might be.
Feature
Provided
by
Advantage
National 4/5 Biology Course Unit 2
Protecting the lungs
This shows
bacteria
(orange)
trapped by
mucus (blue)
on the tiny
cilia cells.
National 4/5 Biology Course Unit 2
The airways of the lungs are lined by
special cells which produce mucus – a
sticky substance to trap microorganisms, dust and dirt.
The airways also have special hair-like
cells called cilia who move upwards in a
wave-like motion to move the trapped
germs and dirt out of the lungs.
National 4/5 Biology Course Unit 2
Transport in animals: Digestive
system
LI:
1. Identify the structures of the
digestive system.
2. Describe the process of peristalsis.
3. Describe the structure of the villi.
4. Explain the role of the villi in the
transport of the products of digestion.
National 4/5 Biology Course Unit 2
The digestive system
The digestive system allows large
insoluble food molecules to be broken
down into small soluble food molecules
and be absorbed into the blood.
National 4/5 Biology Course Unit 2
Collect
and label
this
diagram
Mouth
Tongue
Gullet or
Oesophagus
Liver
Stomach
Pancreas
Gall Bladder
Small
Intestine
Bile Duct
Large
Intestine
Appendix
National 4/5 Biology Course Unit 2
Rectum
Anus
00:00:00
Food is swallowed and
crushed by the teeth. Mixed
with saliva.
00:00:10
Food enters stomach,
where it is mixed with
acid.
03:00:00
Food is now a creamy
liquid – goes to the
small intestine
20:00:00
06:00:00
Food
reaches the
mid-point of
the small
intestine
Food enters
large intestine.
Where water is
absorbed.
National 4/5 Biology Course Unit 2
32:00:00 Undigested food leaves the body
Use available resources find out what the
following organs do:
Salivary glands, Oesophagus, Stomach,
small intestine and large intestine
• Standard Grade biology revision books
• BBC Bitesize standard grade Biology –
Animal Survival – The need for food.
National 4/5 Biology Course Unit 2
Peristalsis
Food is moved through
the digestive system by
the process of
Peristalsis.
Peristalsis occurs along
the length of the
alimentary canal and not
just in the oesophagus.
National 4/5 Biology Course Unit 2
Contractions of the gut wall (peristalsis)
pushes food through from the oesophagus
to the stomach, small intestine, large
intestine, rectum and anus.
Muscles behind the
food contract.
Muscles in front of
the food relax.
National 4/5 Biology Course Unit 2
The small intestine
The teeth, enzymes and stomach are
responsible for breaking the food down.
It is the job of the small intestine to
absorb the food molecules into the
blood stream.
National 4/5 Biology Course Unit 2
Small intestine: Villi
The lining of the
small intestine
is lined with
millions of tiny
finger-like villi.
National 4/5 Biology Course Unit 2
Capillary Absorbs products
of carbohydrate
(glucose) and
protein digestion
(amino acids)
Lacteal – Absorbs
the products of fat
digestion (fatty
acids and glycerol)
National 4/5 Biology Course Unit 2
Efficient food absorption
The small intestine and the villi are
perfectly adapted to absorb food
molecules quickly and efficiently.
National 4/5 Biology Course Unit 2
Read page 209 of textbook.
Complete the following table. Think about and
discuss what the “advantage” might be.
Feature
Provided
by
Advantage
National 4/5 Biology Course Unit 2
Effects of lifestyle choices
of animal transport and
exchange systems
Lifestyle choices
LI:
1. Explain how poor diet and lack of
exercise can affect the transport and
exchange systems causing diseases.
2. Explain how smoking tobacco and
drinking alcohol can affect transport
and exchange systems and how this
causes diseases.
National 4/5 Biology Course Unit 2
Diet
Health problems due to diet are caused
by consuming more fat than we need.
A certain amount of fat in the diet is
important as a source of energy,
insulating our bodies and making cell
membranes.
National 4/5 Biology Course Unit 2
Excess fat can cause health problems:
1. Makes us overweight – puts a strain on
the heart.
2. Increase the levels of cholesterol in
blood. Cholesterol can build up in the
arteries forming plaques. These block
up arteries causing atherosclerosis. If
heart arteries are narrowed/blocked a
heart attack can occur. Blockages in
the brain can cause a stroke.
National 4/5 Biology Course Unit 2
Extra salt in the diet can also cause
problems:
• Increased blood pressure –
hypertension – puts a strain on the
heart and arteries. This increases your
chances of having a heart attack or
stroke.
National 4/5 Biology Course Unit 2
Exercise
Regular exercise and an active lifestyle
prevents obesity (excess body fat) and
increases circulation (blood flow) to the
muscles.
Obesity is a major risk factor for
developing type 2 diabetes, heart
disease and colon cancer.
National 4/5 Biology Course Unit 2
Poor circulation is a risk factor for deep
vein thrombosis (DVT) – when veins get
blocked causing damage to the limbs
affected.
National 4/5 Biology Course Unit 2
Smoking and alcohol abuse
Using pages 214 and 215
Make a short summary of the health risks
associated with:
1. Smoking
2. Alcohol
National 4/5 Biology Course Unit 2