Cambridge IGCSE™
* 1 2 6 0 5 8 1 3 5 8 *
BIOLOGY
0610/42
Paper 4 Theory (Extended)
May/June 2021
1 hour 15 minutes
You must answer on the question paper.
No additional materials are needed.
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
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You may use a calculator.
●
You should show all your working and use appropriate units.
INFORMATION
●
The total mark for this paper is 80.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 20 pages. Any blank pages are indicated.
DC (KN/FC) 202969/5
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1
(a) Complete the sentence about the nervous system.
and
The brain and spinal cord form the ............................................... nervous system and the
Ǘ
nerves coming into and out of the spinal cord are part of the ...............................................
nervous system.
per
[1]
(b) Fig. 1.1 shows part of a human eye and three neurones that conduct electrical impulses
between the eye and the brain. These neurones are involved in the pupil reflex.
K
J
A
H
B
C
G
onto
F
E
D
焄
not to scale
Fig. 1.1
(i)
State the type of neurone identified as A in Fig. 1.1.
Jenny neuron
..................................................................................................................................... [1]
motor
说不出话
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(ii)
Table 1.1 shows the names of some parts of the eye, their functions and the letters in
Fig. 1.1 that identify the parts of the eye.
Complete Table 1.1.
Table 1.1
part of the eye
suspensory ligament
function
Connects the
ciliary
letter in Fig. 1.1
muscles
G
wit in
contracts in response to a bright light
refracting
cornea
tǘ
(c) (i)
Ī
contains a high density of cones for colour
vision
[4]
The eye can adjust how light is refracted through it in order to focus on a near object.
State one process that uses energy when focusing on a near object.
muscle
corny
..................................................................................................................................... [1]
(ii)
Mitochondria require oxygen to release energy. Oxygen is transported to cells in the eye
by red blood cells.
haemoglobin
State the name of the molecule in red blood cells that carries oxygen.
..................................................................................................................................... [1]
(iii)
hemoglobin
Explain how oxygen in the capillaries reaches the cells in the eye.
diffuses
diffusion隐The oxygen
By
...........................................................................................................................................
through the single cell cell wall of coping
...........................................................................................................................................
to the eels in the
due the
eye
concentatimgradient.LT 我说你别急
...........................................................................................................................................
...........................................................................................................................................
molecules
..................................................................................................................................... [2]
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(d) Eyelashes and eyelids are mechanical barriers that help to prevent particles and pathogens
entering the eye.
(i)
Give two other mechanical barriers that defend the body against pathogens.
nosed
1 ........................................................................................................................................
2 ........................................................................................................................................
[2]
(ii)
State the name of the white blood cells that digest pathogens.
..................................................................................................................................... [1]
sky phagoc .gg
(iii)
Conjunctivitis can be caused by pathogens and affects the tissues lining the eyelids and
covering the sclera. People with conjunctivitis that is caused by a pathogen can develop
active immunity.
Explain why the shape of specific parts of a pathogen is important in the development of
active immunity.
...........................................................................................................................................
pathogen'The
antigens on the pathogens enable
...........................................................................................................................................
the lymphocytes to recognise the
Shut
type
unique
...........................................................................................................................................
coma
me
Pathogen and produce the
A
antibodies ...........................................................................................................................................
antibodies t bind with them so that the
mat...........................................................................................................................................
can slow down and be killed by phagocytes
pipe
antigens
able
Memory cells produced
recognise
.....................................................................................................................................
[3]
and produce the antibodies faster
...........................................................................................................................................
are
to
(e) Most insects and some crustaceans have compound eyes.
State the name of the group that contains insects and crustaceans.
inverti
............................................................................................................................................. [1]
arthropods
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2
The classification of giant pandas, Ailuropoda melanoleuca, is debated by many scientists.
Fig. 2.1 shows a giant panda eating bamboo plants.
Fig. 2.1
Fig. 2.2 shows a red panda, Ailurus fulgens, and a polar bear, Ursus maritimus.
o
red panda eating bamboo plants
polar bear eating fish
Fig. 2.2
(a) State one dietary component that is more likely to be found in bamboo plants than in fish.
plant
............................................................................................................................................. [1]
(b) (i)
State two features, visible in Fig. 2.1 and Fig. 2.2, that identify the three animals as all
belonging to the same vertebrate group.
the
型品品望
弘⼀
1 ........................................................................................................................................
2 ........................................................................................................................................
[2]
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(ii)
DNA can also be used to classify species.
Molecular biologists compared the DNA base sequences of eight species from the same
vertebrate group. They used the differences to draw a classification diagram.
Fig. 2.3 shows the classification diagram for these eight species. The shorter the
horizontal distance from two species to the branching point that they share, the more
similar their DNA sequences are and the more closely the two species are related.
The scale on Fig. 2.3 shows the time at which the molecular biologists estimate that
each branching point occurred.
red panda
ferret
o
giant panda
polar bear
wolf
tiger
human
mouse
100
80
60
40
million years ago
Fig. 2.3
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0
7
Morphology can also be used to classify species. Some scientists think that morphology
suggests that the giant panda is more closely related to the red panda than it is to the
polar bear.
Discuss the evidence for and against the giant panda being more closely related to
habitats
the red panda than it is to the polar bear. Use the information in Fig. 2.1, Fig. 2.2 and
Fig. 2.3 in your answer.
similar
position
...........................................................................................................................................
Dearsimilar For i D Giant pandais more close
grey
red panda acceding morphbgy
...........................................................................................................................................
Giant panda and red panda both
is
to
...........................................................................................................................................
to
plant
D Giant
eat
...........................................................................................................................................
Against
...........................................................................................................................................
hhafplmgbearha mnec.be
DNA
...........................................................................................................................................
sequence
Giant Panda and par bears
...........................................................................................................................................
size is cbs
...........................................................................................................................................
成
shrterkanchdisanstuithp.la
...........................................................................................................................................
bear
...........................................................................................................................................
..................................................................................................................................... [5]
(iii)
State one other type of evidence that is used to classify species.
apparel
..................................................................................................................................... [1]
[Total: 9]
anatomy
ability
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fertile offsprings
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3
(a) Fig. 3.1 shows some of the events that occur in the menstrual cycle.
A
i
follicle is fully developed
B
gamete is released into the oviduct
C
lining of the uterus is removed from the body
D
lining of the uterus reaches a maximum thickness
E
lining of the uterus gets thicker
(i)
Fig. 3.1
Put the events shown in Fig. 3.1 into the correct sequence.
One has been done for you.
E
(ii)
Ait
B
c
[1]
State the name of the hormone that stimulates event A to occur.
n
FSH
them 的
release
.....................................................................................................................................
[1]
not
(iii)
Event C means that menstruating females lose blood regularly.
Two females of the same age have different dietary needs because one has started
menstruating and the other has not started menstruating.
Suggest why the dietary needs of the two females are different.
needs
...........................................................................................................................................
who
men
has started
The one
stung
...........................................................................................................................................
a make
bbodbss.int
her
body
up
...........................................................................................................................................
She
need more Irons in her dietary
may
...........................................................................................................................................
need u hid in es send for transport of
..................................................................................................................................... [2]
oxygen
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(b) During pregnancy menstruation does not occur.
Fig. 3.2 shows some of the organs of a pregnant woman, viewed from the side.
fetus
P
V
Q
U
T
R
S
Fig. 3.2
Describe what happens between ovulation and the formation of a fetus.
Use the letters in Fig. 3.2 to support your answer.
at Q theovary
then
...................................................................................................................................................
ovulation news
It
moves to
dig
shapbr
the
P and
...................................................................................................................................................
oviduct
fuses with
sperm
fdnule_r.yusatfwhichtlhespemB.com
ing fan
...................................................................................................................................................
and R cervix.The formed
ads.vagina
...................................................................................................................................................
the
tigre
...................................................................................................................................................
meantime
uterus
continues to move to
int
The embryo eventually
...................................................................................................................................................
and umbilical
the uterus wall T
Phil
...................................................................................................................................................
and U is formed to provide neon and
...................................................................................................................................................
wastes exchange for the fetus via diffusion
...................................................................................................................................................
differencing
implants into
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
............................................................................................................................................. [6]
[Total: 10]
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4
(a) Climate change is one reason why a plant species could become endangered.
(i)
State other reasons why a plant species could become endangered.
monoculture of crops
...........................................................................................................................................
deforestation
...........................................................................................................................................
natural disasters
...........................................................................................................................................
醼
plant doses
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [3]
(ii)
Describe how human actions are causing climate change.
ssim.hr
Esteem
emission
...........................................................................................................................................
Human
increase
for foie an
farming of animals
example
and soon.Also
...........................................................................................................................................
like
increase the
...........................................................................................................................................
cows
of
emissimduett
amount
...........................................................................................................................................
dige.nu
inside it BothCo2
...........................................................................................................................................
the
CHzanegcggns.es
...........................................................................................................................................
cause climate change which taps heat
reactions
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [4]
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(b) Seed banks are used to conserve endangered plant species.
Fig. 4.1 shows some of the steps involved in managing a seed bank.
seeds are collected from
many populations of
each species
seeds are checked using
X-rays
seeds are stored at low
temperatures in the
seed bank
variationpollination
genetic cross
a small sample of seeds
is germinated
ensure chae of
more
chaaesofsuaesshngermnatm
io
Fig. 4.1
increases
(i) Explain why seeds from one species are collected from many populations to store in a
seed bank.
ensure the average
尴
required
quality and
our
...........................................................................................................................................
the seeds
different populations
...........................................................................................................................................
are
The
kind A species
...........................................................................................................................................
the same growth environment requirements as
...........................................................................................................................................
same
easier grow
ueaghave.fr
...........................................................................................................................................
makes it
to
a
same
result
species
Seed bank is able
to
endangered
...........................................................................................................................................
conserve
plant species
..................................................................................................................................... [3]
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(ii)
Seeds are X-rayed before they are stored to check that they contain an embryo.
State one possible consequence of using ionising radiation on seeds.
mu
Ǘ
...........................................................................................................................................
..................................................................................................................................... [1]
(iii)
Seeds stored at low temperatures have very low respiration rates.
Explain why.
certain
enzyme requires
...........................................................................................................................................
range to reach activation energy to let
...........................................................................................................................................
t
take place low temperatures
the reaction doesnh
...........................................................................................................................................
a
respiration's
in
gslei.tk
...........................................................................................................................................
neat
to tak place and let the enzyme each t
One purpose
of seed banks is to reintroduce plant species into their natural environment.
optimum
engine
..................................................................................................................................... [2]
(c)
A survey was done to find out why some reintroduction programmes are not successful.
Fig. 4.2 shows the results of the survey.
40
35
30
percentage of
species that
were not
successfully
reintroduced
25
20
15
10
5
0
reason
unknown
wrong
habitat
changing seeds did seedlings too few
habitat
not
too young individuals
germinate
reasons why reintroductions failed
Fig. 4.2
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wrong
season
13
(i)
Some of the seeds in the reintroduction programmes did not germinate.
State the conditions that are necessary for seeds to germinate.
跮
Oxygen Suit
water
...........................................................................................................................................
a
吣 m
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [3]
(ii)
Some reintroduction programmes failed because the seedlings were too young. Young
seedlings only have a few small roots.
Explain why it would be important to reintroduce plants with many large roots.
absorb sufficient
...........................................................................................................................................
nutrients mineral and water from the soil
...........................................................................................................................................
Minerals like IN
P k Mg containing
...........................................................................................................................................
substones are essential A growth
allow them
Large
...........................................................................................................................................
to
roots
and fruit
phot
synthesis
for
development Water is
...........................................................................................................................................
essential
reactions take place like respiration
...........................................................................................................................................
Small
have
limited ability of
...........................................................................................................................................
absorbing
roots
reintroducing plants with
...........................................................................................................................................
nutrients
so
enough
B
.....................................................................................................................................
[4]
0
rots
i
(iii)
many large
呻
The low number of individuals also caused some reintroduction programmes to fail.
State the name of the phase in a population growth curve where the number of individuals
is very low.
㘜
..................................................................................................................................... [1]
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5
Fig. 5.1 shows some of the stages in the reproduction of the bacterium Escherichia coli.
loop of DNA
original bacterial cell
bacterial cell expands to a critical length
and a copy of DNA is synthesised
daughter cells are formed
daughter cells grow
Fig. 5.1
(a) Complete the sentences about the cells in Fig. 5.1.
The DNA is in the form of a double ............................................... . The DNA is copied so
that the number of loops of DNA after cell division is ...............................................
in each
嚡
identical
daughter cell. The daughter cells are genetically ............................................... to the original
cell.
[3]
(b) Students used a microscope and time-lapse photography to observe E. coli cells reproducing.
They used the series of photographs to identify which cells were dividing.
They measured the lengths of the dividing cells and put their data into two groups:
•
cell lengths immediately before cell division
•
cell lengths immediately after cell division.
Fig. 5.2 shows their results.
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key:
100
immediately after division
immediately before division
90
80
70
60
number
of
cells
50
40
30
20
10
0
0
1
2
⼝
3
5
4
6
cell length / μm
7
8
9
10
Fig. 5.2
(i)
Yg
Use the information in Fig. 5.2 to state the most frequent cell length of the E. coli cells
immediately after cell division.
Give your answer in millimetres.
我真 你
95 Nm
o
(ii)
095mm
......................................................... mm
[2]
Some students concluded that the cells must be at least 6 µm in length before cell
division can occur.
Describe the evidence against the students’ conclusion. Use the information in Fig. 5.2
to support your answer.
There
cells that are below Gum
...........................................................................................................................................
are
cell
length
ltecellisio
somecelbae.be
...........................................................................................................................................
...........................................................................................................................................
then 3mm
after
...........................................................................................................................................
chim
o
..................................................................................................................................... [2]
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(c) Bacteria are useful in genetic engineering because they contain plasmids.
(i)
A
restriction
Describe how a plasmid
is cut so that a new gene can be inserted into the plasmid.
A
endonuclease
...........................................................................................................................................
cut
to make to
By using
...........................................................................................................................................
end at the plasmid
and
filth
..................................................................................................................................... [2]
(ii)
List two reasons, other than the presence of plasmids, that make bacteria and
single-celled fungi useful to biotechnology industries.
usingen
died
They
2 ........................................................................................................................................
They all share the San
DNA
[2]
1 ........................................................................................................................................
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qdfg
[Total: 11]
17
6
(a) Some students set up the apparatus shown in Fig. 6.1 to compare transpiration in two sets of
leaves.
Set A was kept in a transparent bag and set B was left in the open air.
All other conditions were kept constant.
The mass of the leaves in each set was measured at the start of the investigation and after
five hours.
string line
paper clip
clamp stand
transparent bag
set A
set B
Fig. 6.1
(i)
Predict the results for this investigation.
Explain the reason for your prediction.
be heavier
would
prediction ...........................................................................................................................
set A
...........................................................................................................................................
点赞idhmuyneae
explanation ........................................................................................................................
...........................................................................................................................................
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(ii)
Explain how transpiration occurred in the leaves shown in Fig. 6.1.
and
water man
gas
...........................................................................................................................................
diffuses out through the sonata down
The
...........................................................................................................................................
becomes
the
concentrating
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [3]
(iii)
The students needed two additional pieces of apparatus to take measurements so that
they could calculate the rate of transpiration from their results.
State the two additional pieces of apparatus the students needed to take the
measurements.
timer
1 ........................................................................................................................................
balance.lvscale
2 ........................................................................................................................................
[2]
(b) Fig. 6.2 shows the positions of the different tissues in part of a dicotyledonous leaf.
P
汽
Fig. 6.2
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Identify the tissues described in Table 6.1 by:
•
drawing label lines with the corresponding letter on Fig. 6.2 and
•
stating the name of each tissue in Table 6.1.
The label, line and name of the tissue for letter P has been completed for you on Fig. 6.2 and
in Table 6.1.
Table 6.1
letter
description
P
a protective transparent layer that allows light
to reach the inner tissues
Q
conducts water from the stem
R
contains many interconnected air spaces
name of the tissue
upper epidermis
xyleml spmgmesopgl ph palisade.me
S
transports sucrose and amino acids
T
traps the most light energy to synthesise
carbohydrates
sphgk
[4]
[Total: 12]
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