Centre Number Candidate Number Name

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

General Certificate of Education Ordinary Level
BIOLOGY 5090/02
Paper 2 Theory
May/June 2006

1 hour 45 minutes
Additional Materials: Answer Booklet/Paper

READ THESE INSTRUCTIONS FIRST

Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use a pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, highlighters, glue or correction fluid.

Sections A
Answer all questions.
Write your answers in the spaces provided on the Question Paper.

Section B
Answer all the questions including questions 6, 7 and 8 Either or 8 Or.
Write your answers on the separate Answer Paper provided.
At the end of the examination,
1. fasten all your work securely together;
2. write an E (for Either) or an O (for Or) next to the number 8 in the grid below to indicate which question
you have answered.

The number of marks is given in brackets [ ] at the end of each question or part question.
You are advised to spend no longer than one hour on Section A and no longer than 45 minutes on Section B.

For Examiner’s Use

Section A

Section B

Total

This document consists of 13 printed pages and 3 blank pages.

SP (SLM/CGW) T10870/2
© UCLES 2006 [Turn over
 2 For
Examiner’s
Use
Section A

Answer all the questions in this section.

Write your answers in the spaces provided.

1 Fig. 1.1 shows the cell membrane of an animal and a plant cell.

animal cell plant cell

Fig. 1.1

(a) On Fig. 1.1, draw and label

(i) one other structural feature that is found in both cells,

(ii) two features found in a plant cell but not in an animal cell.
[3]

© UCLES 2006 5090/02/M/J/06

 3 For
Examiner’s
Use
Table 1.1 shows the average amounts of protein, fat and carbohydrate found in some plant
and some animal tissues (expressed as a percentage of the total mass).

Table 1.1

protein fat carbohydrate

plant tissues 5 1 30
animal tissues 20 15 1

(b) (i) Explain why there is a high percentage of carbohydrate in the plant tissues.

..................................................................................................................................

..............................................................................................................................[2]

(ii) Name an animal tissue that would have much more than the 1% carbohydrate
shown in Table 1.1. Explain your choice of tissue.

tissue .........................................................................................................................

explanation ................................................................................................................

..............................................................................................................................[3]

(iii) Suggest reasons for the differences in the protein and in the fat content of the plant
and animal tissues.

protein .......................................................................................................................

..................................................................................................................................

fat ..........................................................................................................................[3]

[Total: 11]

© UCLES 2006 5090/02/M/J/06 [Turn over

 4 For
Examiner’s
Use
2 (a) (i) State the name for chemicals that are secreted by glands into the blood and that
affect organs elsewhere in the body.

................................................[1]

(ii) State the term used to describe the organs that are affected by these chemicals.

....................................organs [1]

(b) Listed below are a number of responses shown by the human body:

A the amount of saliva produced increases

B the concentration of blood glucose falls

C the concentration of blood glucose rises

D the pupils become smaller

E the rate of heart beat increases

Which two of these are responses to the release of adrenaline?

1. ......................................................................................................................................

2. ..................................................................................................................................[2]

© UCLES 2006 5090/02/M/J/06

 5 For
Examiner’s
Use
(c) Fig. 2.1 shows the blood glucose concentrations of three different people, G, H and I,
over a 48-hour period.

20 day 1 day 2

15
G
blood glucose H
concentration/ 10
arbitrary units

5
I

0
08.00 14.00 20.00 02.00 08.00 14.00 20.00 02.00 08.00

time of day

Fig. 2.1

Two of the people are diabetic. The pancreas of one of these produces small quantities of
insulin. In the other, the pancreas produces no insulin. The third person is not diabetic.

Using the information in Fig. 2.1 and giving a reason for your answer in each case,
identify

(i) the person without diabetes .............

reason: ......................................................................................................................

(ii) the person who produces no insulin ............

reason: ......................................................................................................................
[4]

(d) Diabetes can be treated by injection of insulin. Insulin can now also be taken by breathing
it in. Suggest how insulin taken by breathing it in enters the blood.

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

[Total: 11]

© UCLES 2006 5090/02/M/J/06 [Turn over

 6 For
Examiner’s
Use
3 Fig. 3.1 shows a section through a flower and also what happens to some of its parts during
the plant’s life.

stigma stigma magnified

M

x6

young flower x 2
ovule

fruit x 2

x2

Fig. 3.1

© UCLES 2006 5090/02/M/J/06

 7 For
Examiner’s
Use
(a) Identify structures M.

......................................................................................................................................[1]

(b) Structures M have come from another flower. Describe how structures M have been
transferred and become attached to this stigma.

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(c) Describe what happens to the ovule inside the young flower for it to develop into
structure N inside the fruit.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[4]

(d) Name the process occurring at P.

......................................................................................................................................[1]

[Total: 8]

© UCLES 2006 5090/02/M/J/06 [Turn over

 8 For
Examiner’s
Use
4 Fig. 4.1 shows the average sweating rates of a person over a 4-hour period under different
conditions.

walking naked in the sun

walking clothed in the sun carrying 15 kg

walking clothed in the sun

sitting naked in the sun

sitting clothed in the sun

sitting clothed
in the shade

0 200 400 600 800 1000 1200

sweating rate / gh-1

Fig. 4.1

(a) State two ways other than by sweating in which a person might lose water.

1. ......................................................................................................................................

2. ..................................................................................................................................[2]

© UCLES 2006 5090/02/M/J/06

 9 For
Examiner’s
Use
(b) State and explain how the rates of sweating shown in Fig. 4.1 are different for the
person when they are

(i) walking and sitting,

..................................................................................................................................

..................................................................................................................................

(ii) clothed and unclothed,

..................................................................................................................................

..................................................................................................................................

(iii) in the sun and in the shade.

..................................................................................................................................

..................................................................................................................................
[6]

(c) Suggest an explanation for the effect that carrying 15 kg has on the person’s rate of
sweating.

..........................................................................................................................................

......................................................................................................................................[2]

[Total: 10]

© UCLES 2006 5090/02/M/J/06 [Turn over

 10 For
Examiner’s
Use
5 Fig. 5.1 shows a method used by a student to understand how characteristics are inherited
when two plants of species X are crossed. Both cubes had three of their faces marked with
the letter T and three with the letter t.

shaking

cube 1 cube 2

In this example, the letters appearing on the upper faces are Tt.

Fig. 5.1

The student shook each container and then tipped both cubes out at the same time and
recorded the letters appearing on the upper faces of the cubes.

The student tipped both cubes out a total of 405 times.

(a) (i) Complete Table 5.1 to show the results obtained.

Table 5.1

letters appearing on the upper faces of the cubes tt TT Tt

number of times each pair of letters appeared 98 ....... 202

[1]

(ii) State what the letters on the faces of the cubes represent.

..............................................................................................................................[1]

(iii) State the reason for shaking the containers.

..............................................................................................................................[1]

© UCLES 2006 5090/02/M/J/06

 11 For
Examiner’s
Use
(b) In living plants of species X, items T and t control flower colour. The genetic diagrams
below show a sequence of crosses (V and W) between plants of species X, some with
red flowers and some with yellow flowers.

cross V
� parental generation:

F1 generation:
red ´ yellow
↓
all red flowers

cross W
� F1 generation from cross V :

F2 generation :
red ´ red
↓
red flowers and yellow flowers

Using the information in Table 5.1 and crosses V and W,

(i) state which colour is dominant and which of cross V and cross W could produce
the results seen in Table 5.1

dominant colour, .......................................................................................................

cross. ....................................................................................................................[1]

(ii) Explain why you chose this cross.

..................................................................................................................................

..............................................................................................................................[1]

© UCLES 2006 5090/02/M/J/06 [Turn over

 12 For
Examiner’s
Use
(c) (i) Using the letters T and t, draw a full genetic diagram for another cross, Y, between
plants of species X shown below.

cross Y
� parental generation:

offspring:
red ´ yellow
↓
red flowers and yellow flowers

[4]

(ii) In the method shown in Fig. 5.1, the student put T on three faces and t on the
other three faces of each cube, so that cube 1 had T, T, T, t, t, t and cube 2
T, T, T, t, t, t.

State what letters the student should write on the faces of each cube to represent
the cross in (c)(i).

cube 1 ..................

cube 2 .................. [1]

[Total: 10]

© UCLES 2006 5090/02/M/J/06

 4 For
Examiner’s
Use
2 Fig. 2.1 shows a comparison of water vapour loss by a plant growing in damp soil and a plant
growing in dry soil.

16

12 plant in damp soil

water vapour
loss / arbitary
units
8

4
plant in dry soil

0
08:00 10:00 12:00 14:00 16:00 18:00 20:00
time of day

Fig. 2.1

(a) (i) State the term for the loss of water vapour by a plant.

..............................................................................................................................[1]

(ii) State the time of day when the total water vapour loss from the two plants taken
together is the greatest.

..............................................................................................................................[1]

© UCLES 2006 5090/02/O/N/06

 5 For
Examiner’s
Use
(b) (i) Explain the rise in the rate of water vapour loss between 08:00 and 10:00 by the
plant in damp soil.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..............................................................................................................................[4]

(ii) Suggest why the rate of water vapour loss from the plant in dry soil decreased
during the same period of time.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..............................................................................................................................[2]

(c) Suggest why the temperature of the plant in dry soil may be higher at mid-day than that
of the plant in damp soil.

..........................................................................................................................................

......................................................................................................................................[2]

[Total: 10]

© UCLES 2006 5090/02/O/N/06 [Turn over

 6 For
Examiner’s
Use
3 Fig. 3.1 shows how a blocked blood vessel in the heart can be by-passed using an artificial
blood vessel.

artificial blood vessel

fixed into vessel P
Q

blocked
blood vessel

Fig. 3.1

(a) (i) Name the blocked blood vessel. ...........................................................................[2]

(ii) Identify structures P and Q on Fig. 3.1.

P ......................................................................

Q ..................................................................... [2]

(b) Sometimes, instead of an artificial blood vessel being used for the graft, a vein is taken
from elsewhere in the patient’s body.

Suggest two ways in which a vein might not be as suitable for carrying blood to the heart
muscle as the blood vessel in the heart before it became blocked.

1 .......................................................................................................................................

2 ...................................................................................................................................[2]

© UCLES 2006 5090/02/O/N/06

 7 For
Examiner’s
Use
(c) Fig. 3.2 shows the same blood vessel, as in (a)(i) but this time the blockage is being
treated with the use of a ‘stent’.

same blood vessel with

R ʻstentʼ in place

blood vessel with blockage R a ʻstentʼ (a small tube of

stainless steel mesh)

Fig. 3.2

(i) Name two components of the material that is causing the blockage at R.

1 ...............................................................................................................................

2 ...........................................................................................................................[2]

(ii) Suggest and explain why patients are given ‘anti-platelet’ drugs before inserting the
stent.

..................................................................................................................................

..................................................................................................................................

..............................................................................................................................[2]

[Total: 10]

© UCLES 2006 5090/02/O/N/06 [Turn over

 8 For
Examiner’s
Use
4 Dry mass is the mass of all chemicals, excluding water, present in a structure or organism.

Some seeds were placed in an incubator at 25 °C and left to germinate and grow in the dark
for 5 days.
Table 4.1 shows dry mass in samples of the resulting seedlings.

Table 4.1

day 0 day 1 day 2 day 3 day 4 day 5

whole seeds / g 225 210 208 206 175 155
food store / g 200 183 180 168 129 96
radicle and
2 4 5 15 23 36
plumule only / g

(a) (i) Water is needed for germination. State another condition necessary for
germination.

..............................................................................................................................[1]

(ii) Name the food storage region in a seed.

..............................................................................................................................[1]

(iii) Explain why the total mass of the food storage region together with the radicle and
plumule is always less than the mass of the whole seedling.

..............................................................................................................................[1]

(b) Explain the changes in mass over the first five days of

(i) the food storage region,

..................................................................................................................................

..................................................................................................................................

..............................................................................................................................[2]

(ii) the radicle and plumule.

..................................................................................................................................

..............................................................................................................................[2]

© UCLES 2006 5090/02/O/N/06

 9 For
Examiner’s
Use
(c) If the seedlings were exposed to light from day 2 to day 5, suggest and explain what
would happen to the dry masses of

(i) the food storage region,

..................................................................................................................................

..................................................................................................................................

(ii) radicle and plumule.

..................................................................................................................................

..................................................................................................................................
[4]

[Total: 11]

© UCLES 2006 5090/02/O/N/06 [Turn over

 10 For
Examiner’s
Use
5 Fig. 5.1 shows the development of a zygote into a fetus.

B C D E

Fig. 5.1

(a) State whereabouts in the female reproductive system structure C would be found.

......................................................................................................................................[1]

(b) Name the type of cell division occurring in Fig. 5.1.

......................................................................................................................................[1]

(c) Describe what happens to structure D to enable it to continue to develop into a fetus.

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(d) If the embryo’s mother had blood group A and its father had blood group B, complete
the grid below to show how the embryo could have blood group O. Use IA, IB and Io to
represent the alleles and clearly indicate any embryo that has blood group O.
p r

fa up
ou e
gr oth

gr
A

th B
o
er
m

es

ga
et

m
m

et
ga

es

[4]

[Total: 8]
© UCLES 2006 5090/02/O/N/06
 2

Section A For
Examiner’s
Answer all the questions in this section. Use

Write your answers in the spaces provided.

1 Fig. 1.1a shows the absorption and release of gases by an animal and by a leaf of a plant
during the day.

Fig. 1.1a

(a) Name

(i) gas A, .................................................

(ii) gas B. ................................................. [2]

(iii) On Fig. 1.1b, place arrow heads on the four lines to indicate the movement of the
same gases during the hours of darkness. [3]

Fig. 1.1b

© UCLES 2008 5090/02/M/J/08

 3

(b) Explain why, in the early morning and in the evening, there is no overall movement of For
gases into or out of the leaf. Examiner’s
Use

.........................................................................................................................................

.........................................................................................................................................

.........................................................................................................................................

.................................................................................................................................... [3]

(c) The animal eats the leaf.

Name a chemical substance in the leaf that

(i) will provide the animal with energy,

............................................................

(ii) the animal will use for growth.

............................................................
[2]

[Total: 10]

© UCLES 2008 5090/02/M/J/08 [Turn over

 6

3 Over a period of several months, a student recorded some activities of the wild life in a For
particular habitat. The following observations appeared in her notebook. Examiner’s
Use

1. Young shoots of a crop of bean plants covered with greenflies (aphids)

sucking food from the stems.
2. Saw a large bird (hawk), which usually catches mice, swoop to take a small
yellow bird clinging to a bean stem. Noticed that these small birds often
visit the bean field to eat some of the aphids or butterflies.
3. Flowers of beans being visited by many different species of butterfly.
4. Mice seen nibbling at some dispersed bean seeds.
5. Spider’s web constructed between two bean plants with 5 large black flies
caught in it. Rotting body of a mouse nearby attracting similar flies.

(a) Complete Fig. 3.1 by filling in the names of the organisms to show the feeding
relationships in this community.

bean plants

[4]
Fig. 3.1

(b) (i) What name is given to a chart of feeding relationships as shown in Fig. 3.1?

............................................................ [1]

(ii) Name two top carnivores observed by the student.

1. .........................................................

2. ......................................................... [2]
© UCLES 2008 5090/02/M/J/08
 7

(c) In each space below, For

Examiner’s
(i) draw and label a pyramid of biomass for the hawks, mice and bean plants in this Use

habitat,

[2]

(ii) draw and label a pyramid of numbers for a bean plant, small birds and aphids.

[2]

[Total: 11]

© UCLES 2008 5090/02/M/J/08 [Turn over

 8

4 Fig. 4.1 shows diagrammatically the action of enzymes on two different food molecules. For
Examiner’s
Use

action of enzyme

fat molecule D molecules E

action of enzyme G

starch

molecules F

Fig. 4.1

(a) Identify the molecules shown in Fig. 4.1.

D ......................................................

E ......................................................

F ...................................................... [3]

(b) Identify enzyme G. ...................................................... [1]

© UCLES 2008 5090/02/M/J/08

 9

(c) It has been found that fresh pineapple contains an enzyme that can be used to make For
meat more tender. Examiner’s
Use

(i) Explain why the pineapple is placed on the meat a few hours before, rather than
during, cooking.

.................................................................................................................................

.................................................................................................................................

..................................................................................................................................

............................................................................................................................ [3]

(ii) Suggest the name of the enzyme and how it tenderises the meat.

.................................................................................................................................

.................................................................................................................................

..................................................................................................................................

............................................................................................................................ [3]

[Total: 10]

© UCLES 2008 5090/02/M/J/08 [Turn over

 10

5 Fig. 5.1 shows a green plant (H) that is partially parasitic on its host plant. For
Examiner’s
Use

stem of host plant

green leaves
of plant H

stem fruits
sucker embedded
in veins of the
host plant

Fig. 5.1

(a) (i) Name an organ, found in free-living plants, that is absent in plant H.

............................................................ [1]

(ii) Name the process used by plant H to manufacture its carbohydrates.

............................................................ [1]

Plant H obtains one raw material for food manufacture from the air and other requirements,
as well as nutrients, from its host.

(b) (i) Suggest three substances it absorbs from its host, and for each, state its use in
Plant H.

substance 1 ................................................., use ...................................................

substance 2 ................................................., use ...................................................

substance 3 ................................................., use ...................................................

[6]

(ii) Suggest the name of the tissue in the host plant which supplies these substances
to plant H.

............................................................................................................................ [1]

[Total: 9]

© UCLES 2008 5090/02/M/J/08

 5 For
Examiner’s
Use
3 Fig. 3.1 shows a section through a leaf.

Fig. 3.1

(a) Identify structures J and K.

J ..............................................

K ............................................. [2]

(b) (i) On Fig. 3.1, use arrows to show the pathway taken by water from its arrival in this
part of the leaf until it is lost into the atmosphere. [3]

(ii) Place a large X so that its arms cross as closely as possible to the point at which
evaporation of water is occurring. [1]

© UCLES 2008 5090/02/O/N/08 [Turn over

 6 For
Examiner’s
Use
Fig. 3.2a shows the rates of transpiration for a particular species of plant at different air
temperatures.

rate of
transpiration 4
/ arbitrary units

0
0 10 20 30 40 50
air temperature / °C

Fig. 3.2a

Fig. 3.2b shows the air temperatures and the temperatures inside the leaf at point L in Fig. 3.1
for the same plant during 24 hours.

50

air temperature
40

30

temperature / °C

20
temperature in
leaf at point L

10

0
0600 1200 1800 2400
time of day / h

Fig. 3.2b
© UCLES 2008 5090/02/O/N/08
 7 For
Examiner’s
Use
Fig. 3.2c shows stomata as they appear in this leaf at three different times during the day.

M N O

Fig. 3.2c

(c) Using information provided in Fig. 3.2a and Fig. 3.2b, state which of the stomatal pores,
M, N and O, in Fig. 3.2c, shows their appearance at the following times of day.

(i) 03:00 ...........................

(ii) 19:30 ...........................

[2]

(d) Suggest why the temperature inside the leaf never rises above 30 °C, even though the
air temperature rises much higher than this.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

[Total: 10]

© UCLES 2008 5090/02/O/N/08 [Turn over

 8 For
Examiner’s
Use
4 Fig. 4.1 shows human blood containing pathogenic (disease-causing) organisms.

Fig. 4.1

(a) (i) Name the liquid labelled Q in Fig. 4.1. ................................................................ [1]

(ii) Name two mineral ions which may be found in liquid Q and, for each ion, state its
function in the body.

ion 1 ................................................. function .........................................................

ion 2 ................................................. function .........................................................

[3]

(b) On Fig. 4.1, label

(i) a white blood cell,

(ii) a red blood cell infected with the pathogenic organism.

[2]

(c) The pathogenic organisms were introduced into the blood by a mosquito while feeding.
Suggest why the mosquito feeds from a capillary and not from an artery.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [3]

[Total: 9]

© UCLES 2008 5090/02/O/N/08

 9 For
Examiner’s
Use
5 Fig. 5.1 shows changes in the uterus during the menstrual cycle.

day
28 1 2
27 3
4
26

25

5
4

6
21 22 23 2

10798
20

11
19

R 12
18 13
17 14 15 16

Fig. 5.1

(a) Identify R. ................................................... [1]

(b) State the days when each of the following processes are most likely to occur during the
cycle.

(i) fertilisation ..........................................

(ii) implantation ........................................

[2]

(c) Suggest and explain why blood must not pass directly from the mother to the fetus
during pregnancy, even though it contains substances necessary for fetal development.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [3]

© UCLES 2008 5090/02/O/N/08 [Turn over

 10 For
Examiner’s
Use
Table 5.1 shows that temperature determines whether the eggs of a particular species of
reptile hatch into a male or a female.

Table 5.1

temperature / °C

29 30 31 32 33 34 35 36 37 38

% of females hatching 100 100 99 50 1 0 50 99 100 100

% males hatching 0 0 1 50 99 100 50 1 0 0

(d) (i) State the ranges of temperatures at which females are more likely than males to
hatch from the eggs.

......................................................... and .......................................................... [2]

(ii) State three ways in which the production of a male human child differs from the
production of the male form of this reptile.

1. ...............................................................................................................................

2. ...............................................................................................................................

3. ......................................................................................................................... [3]

[Total: 11]

© UCLES 2008 5090/02/O/N/08

 4

2 The diagram shows apparatus used to study breathing.

pen upper box

containing air
revolving
drum tube to mouthpiece

air to and
from person
water
substance
M

(a) (i) Describe what will happen to the upper box containing air as a person takes one breath
in from the apparatus.

..................................................................................................................................... [1]

(ii) State the percentage of oxygen in atmospheric air.

.............................................. %

Explain how the percentage of oxygen in the air in the upper box will change as a person
breathes in and out through the apparatus several times.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................
[3]

(iii) Substance M is present in the apparatus to absorb an excretory product from expired air.

Name this excretory product.

.......................................................................... [1]

© UCLES 2022 5090/22/M/J/22

 5

(b) The diagram shows a chart recorded by the pen on the revolving drum.

This chart was recorded for a period of one minute by a person at rest.

4
N

volume of air
/ dm3
2

0
0 10 20 30 40 50 60
time / seconds

(i) Explain how the action of one named muscle caused the part of the chart labelled N.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [3]

(ii) A second chart was recorded for a period of one minute by the same person after
vigorous exercise.

State how an increased rate of breathing after exercise would be shown on this second
chart.

...........................................................................................................................................

..................................................................................................................................... [1]

[Total: 9]

© UCLES 2022 5090/22/M/J/22 [Turn over

 6

3 A student carried out two investigations into the action of yeast.

(a) In the first investigation, the student dissolved 20.0 g of glucose in 100 cm3 of water in a
beaker. The student then added 3.5 g of yeast and used a balance to measure the loss in
mass from the beaker over the next 24 hours.

The results of this investigation are shown in the graph.

9.0

8.0

7.0

6.0

5.0
mass lost
/g 4.0

3.0

2.0

1.0

0.0
0 2 4 6 8 10 12 14 16 18 20 22 24
time / hours

(i) Calculate the rate at which mass was lost during the first 6 hours.

Space for working.

......................................... g per hour [2]

© UCLES 2022 5090/22/M/J/22

 7

(ii) Explain why mass was lost during the investigation.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [3]

(iii) The student then repeated this first investigation changing only the mass of yeast.

Draw a line on the graph on page 6 to show the pattern of results you would expect the
student to obtain when using 7.0 g of yeast. [2]

© UCLES 2022 5090/22/M/J/22 [Turn over

 8

(b) In a second investigation, the student prepared three samples of bread dough.

Each sample of dough had a volume of 50 cm3 and contained:

• 1 g of yeast
• 25 cm3 of water
• 40 g of flour.

(i) Starch molecules in the flour are used to provide the yeast with a source of glucose.

Describe how the action of a named chemical, produced by yeast cells, makes glucose
available from starch.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [2]

Each sample of dough was placed at the bottom of a 200 cm3 measuring cylinder.

The three measuring cylinders were then placed in water-baths at different temperatures for
60 minutes. The temperatures chosen were 20 °C, 40 °C and 80 °C.

After this time, the student measured the volume of dough in each measuring cylinder.

The diagram shows the volume of dough in the measuring cylinder from the water-bath at a
temperature of 20 °C at the end of the investigation.

cm3

200
180

160
140

120
100
80
dough
60

40
20

© UCLES 2022 5090/22/M/J/22

 9

(ii) Estimate the volumes of the dough at the end of the investigation in the other two
measuring cylinders, from water-baths at temperatures of:

40 °C ............................................. cm 3

80 °C ............................................. cm 3
[2]

(iii) Explain the results of this investigation.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [3]

[Total: 14]

© UCLES 2022 5090/22/M/J/22 [Turn over

 10

4 There are many different types of amino acid.

One of these is phenylalanine.

The diagram shows the structure of a molecule of phenylalanine.

NH2

CH2 C COOH

(a) Phenylalanine is metabolised by an enzyme with the name PAH.

(i) Name the human organ that metabolises amino acids such as phenylalanine.

.............................................. [1]

(ii) Explain how the shape of a PAH enzyme molecule is important to enable phenylalanine
to be metabolised.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [3]

(b) A rare gene mutation reduces the activity of the PAH enzyme. The mutation results in an
increased concentration of phenylalanine in the blood. This condition can cause damage to
the brain.

(i) Describe what is meant by the term gene mutation.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [2]

© UCLES 2022 5090/22/M/J/22

 11

(ii) Explain how a person with the condition should change their diet to reduce the risk of
damage to the brain.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [3]

(iii) The gene mutation produces a recessive allele, h. A person with a heterozygous
genotype is described as a carrier. A carrier will not show symptoms of the condition.

Complete the genetic diagram to show the probability of two carriers reproducing to have
offspring with the condition.

gametes
............ ............

............ ............ ............

............ ............ ............

probability of offspring with the condition ...............................................................

[3]

[Total: 12]

© UCLES 2022 5090/22/M/J/22 [Turn over

 12

5 (a) Biological processes in plants are affected by environmental factors.

The graphs each show the effect of changing one environmental factor on a biological
process.

The labels on the axes for each graph have been replaced with the letters P, Q, R and S.

P R

Q S

Identify the correct axis label for each of P, Q, R and S.

Select from the following possible labels.

temperature carbon dioxide concentration rate of transpiration

light intensity rate of photosynthesis air humidity

P ...........................................................................................

Q ...........................................................................................

R ...........................................................................................

S ...........................................................................................
[4]

(b) Describe the process of transpiration in the leaf of a plant.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

............................................................................................................................................. [3]

[Total: 7]

© UCLES 2022 5090/22/M/J/22