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Biology Alevels Combined

This document is an examination paper for Cambridge International AS & A Level Biology, specifically Paper 2 AS Level Structured Questions for February/March 2024. It includes instructions for answering questions, information about the total marks, and various structured questions related to biological concepts such as cell membranes, white blood cells, and DNA replication. The paper consists of multiple sections with diagrams and tables that require students to provide detailed answers and explanations.

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18 views340 pages

Biology Alevels Combined

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Cambridge International AS & A Level

* 1 5 3 1 9 0 6 3 5 0 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions February/March 2024

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.
● You may use a calculator.
● You should show all your working and use appropriate units.

INFORMATION
● The total mark for this paper is 60.
● 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 (CJ/SG) 327572/4
© UCLES 2024 [Turn over
2

1 (a) Fig. 1.1 is a diagram representing part of the phospholipid bilayer of a cell surface membrane.

A OH OH OH

cholesterol

fatty acid tails

phosphate heads

OH OH

Fig. 1.1

(i) Identify the part of a phospholipid molecule, labelled A in Fig. 1.1, that forms bonds with
the phosphate heads and with the fatty acid tails.

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

© UCLES 2024 9700/22/F/M/24

(ii) Cholesterol is an important lipid component of many cell surface membranes. Fig. 1.2
shows the structure of a cholesterol molecule.

non-polar part of
cholesterol molecule

polar hydroxyl
group OH

Fig. 1.2

Using the information in Fig. 1.2, explain the orientation (positioning) of cholesterol
molecules in the phospholipid bilayer, as shown in Fig. 1.1.

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

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

(iii) State one role of cholesterol in phospholipid bilayers.

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

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

(b) (i) Explain why sodium ions cannot cross phospholipid bilayers by simple diffusion.

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

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

© UCLES 2024 9700/22/F/M/24 [Turn over

(ii) Ions and some molecules move across cell surface membranes by facilitated diffusion
and active transport.

Compare facilitated diffusion and active transport by stating one way in which they are
similar and two ways in which facilitated diffusion is different from active transport.

similarity ............................................................................................................................

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

difference 1 ........................................................................................................................

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

difference 2 ........................................................................................................................

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

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

(c) Prostaglandins are small lipids produced in many tissues of the body. One role of prostaglandins
is to cause inflammation at the site of an injury or infection. Inflammation is the normal first
response of the immune system to injury or infection.

Cyclooxygenase (COX) is an enzyme that catalyses one of the steps in the reaction pathway
for the formation of prostaglandins from phospholipids. The reaction pathway occurs in the
smooth endoplasmic reticulum (SER) of cells. Part of the reaction pathway is shown in Fig. 1.3.

phospholipid

arachidonic acid

COX

prostaglandin

Fig. 1.3

(i) Suggest an advantage for this reaction pathway occurring in the smooth endoplasmic
reticulum of a cell rather than in the cytoplasm.

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

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

© UCLES 2024 9700/22/F/M/24

(ii) Sometimes inflammation can have side-effects, such as pain. Aspirin is a drug that can
be used to reduce these side-effects.

Aspirin reduces the catalytic activity of the COX enzyme by modifying the R-group of one
of the amino acids.

Suggest how modifying the R-group of an amino acid in the COX enzyme can reduce
the catalytic activity of the enzyme.

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

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

(iii) Prostaglandins are examples of cell-signalling molecules.

Outline the process of cell signalling that leads to a response by the cells involved in
inflammation.

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

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

[Total: 13]

© UCLES 2024 9700/22/F/M/24 [Turn over

2 (a) Table 2.1 shows descriptions of three types of white blood cell.

Complete Table 2.1 by stating the names of these three types of white blood cell.

Table 2.1

description name of white blood cell

A large cell that has a bean-shaped (kidney-shaped)
nucleus. It can develop into a macrophage.
A cell that has a large spherical nucleus and little
cytoplasm. It responds to non-self antigens.
A cell that has a lobed nucleus. It is phagocytic.

[3]

(b) Dromedary camels are classified in the family Camelidae and live in desert habitats of North
Africa and Asia. In these hot, dry environments, dromedary camels can lose up to 30% of
their body mass from dehydration, causing their blood to become more viscous (thicker).

Fig. 2.1 shows a drawing of red blood cells of a dromedary camel. Fig. 2.2 is a drawing of
human red blood cells.

×2000 ×2000

Fig. 2.1 Fig. 2.2

© UCLES 2024 9700/22/F/M/24

Fig. 2.1 and Fig. 2.2 show differences between the red blood cells of dromedary camels and
the red blood cells of humans.

Suggest how these differences adapt dromedary camels for living in hot, dry environments.

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

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

© UCLES 2024 9700/22/F/M/24 [Turn over

(c) The llama is also classified in the family Camelidae. Llamas live in mountainous areas of South
America, often at altitudes of 3500 m or higher. As the altitude above sea level increases, the
air pressure decreases.

The partial pressure of oxygen in the lungs of mammals at 3500 m is 6.4 kPa.

Fig. 2.3 shows the oxygen dissociation curve of adult human haemoglobin and adult llama
haemoglobin.

100
key
90 adult llama
haemoglobin
80 adult human
haemoglobin
70

60
percentage
saturation of 50
haemoglobin with
oxygen
40

0
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
partial pressure of oxygen / kPa

Fig. 2.3

(i) With reference to Fig. 2.3, explain how the differences between the oxygen dissociation
curves for humans and llamas show that llamas are better adapted for living at high
altitudes than humans.

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

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

© UCLES 2024 9700/22/F/M/24

(ii) Sketch a curve on Fig. 2.3 to show the effect of an increased carbon dioxide concentration
on the percentage saturation of adult human haemoglobin with oxygen. [1]

(iii) Explain the importance of the Bohr shift in metabolically active organs, such as the liver.

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

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

[Total: 13]

© UCLES 2024 9700/22/F/M/24 [Turn over

3 (a) Fig. 3.1 is a photomicrograph showing part of a transverse section through the root of an iris,
Iris germanica. Irises are herbaceous monocotyledons. These plants have the same transport
tissues as herbaceous dicotyledons, but the transport tissues are distributed differently. In
monocotyledons, the central tissue in the root is parenchyma (packing tissue).

parenchyma
S

×120

Fig. 3.1

(i) Cells R, S and T in Fig. 3.1 are found in different tissues.

Name the tissues in which the cells labelled R, S and T are found.

tissue in which cell R is found ...........................................................................................

tissue in which cell S is found ...........................................................................................

tissue in which cell T is found ............................................................................................

[3]

(ii) Outline the role of the tissue in which cell R is found in Fig. 3.1.

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

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

© UCLES 2024 9700/22/F/M/24

(iii) State an example of an organic compound that is translocated in the root of an iris.

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

(b) The electron micrograph in Fig. 3.2 shows a section through some root cells in an onion,
Allium cepa.

×6250

Fig. 3.2

On Fig. 3.2, draw a label line and label it with the letter P to identify one plasmodesma. [1]

© UCLES 2024 9700/22/F/M/24 [Turn over

Complete Table 3.1 by filling in the missing information.

Table 3.1

polysaccharide monomer glycosidic bond(s) function

energy storage in
amylopectin α-glucose 1,4 and 1,6
plants

energy storage in
amylose 1,4
plants

structural role in
cellulose β-glucose
plant cell walls

glycogen α-glucose 1,4 and 1,6

[3]

[Total: 10]

© UCLES 2024 9700/22/F/M/24

Question 4 starts on page 14.

© UCLES 2024 9700/22/F/M/24 [Turn over

4 (a) Table 4.1 shows a sequence of 12 nucleotides in the template strand of a short length of a
DNA molecule, the corresponding primary transcript and the four amino acids coded for by
the sequence. The table is incomplete.

(i) Complete Table 4.1 to show the sequence of nucleotides in the primary transcript that
would result from transcription of this short length of DNA.

Table 4.1

position of nucleotide 1 2 3 4 5 6 7 8 9 10 11 12

DNA template strand C A C T A C T C C A A C

primary transcript

amino acid aa1 aa2 aa3 aa4

[1]

(ii) Table 4.2 shows all the possible template strand DNA triplets that code for the amino
acids labelled aa1, aa2, aa3 and aa4 in Table 4.1.

Table 4.2

amino acid DNA triplets

val CAA, CAG, CAT, CAC

arg GCA, GCG, GCT, GCC, TCT, TCC

met TAC

leu AAT, AAC, GAA, GAG, GAT, GAC

Complete Table 4.3 to identify the four amino acids labelled aa1, aa2, aa3 and aa4 in
Table 4.1.

Table 4.3

aa1 aa2 aa3 aa4

amino acid

[1]

© UCLES 2024 9700/22/F/M/24

(iii) One type of gene mutation is caused by the substitution of a DNA nucleotide.

Using the information in Table 4.2, state and explain the effect on the final protein
structure of a substitution of the nucleotide at position 3 in Table 4.1.

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

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

(iv) A second type of gene mutation is caused by the deletion of a DNA nucleotide.

Using the information in Table 4.2, state and explain the effect on the final protein
structure of a deletion of the nucleotide at position 3 in Table 4.1.

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

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

(b) Replication of nuclear DNA occurs just once in every mitotic cell cycle. Six named events
associated with the mitotic cell cycle are listed. The events are not listed in any particular
order.

Draw a circle around each event where replication of nuclear DNA occurs.

cytokinesis

interphase S phase

G2 phase G1 phase

mitosis

[1]

© UCLES 2024 9700/22/F/M/24 [Turn over

(c) Outline how DNA is replicated inside the nucleus.

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

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

(d) Fig. 4.1 shows the structure of an ATP molecule.

NH2
O O O N
N
HO P O P O P O
N N
O
OH OH OH

OH OH

Fig. 4.1

State the name of the part of the ATP molecule labelled A in Fig. 4.1.

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

[Total: 13]

© UCLES 2024 9700/22/F/M/24

5 The pathogen that causes cholera is a prokaryote.

(a) Fig. 5.1 shows an electron micrograph of the pathogen that causes cholera.

Fig. 5.1

(i) Name the type of electron microscope used to produce the image shown in Fig. 5.1.

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

(ii) Name the species of prokaryote that causes cholera.

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

(b) The passage contains a description of the main features of prokaryotic cells. There is one
factual error in the passage.

Prokaryotic cells are unicellular and generally between 1 μm and 5 μm in diameter.

Prokaryotes do not have organelles surrounded by double membranes. They do

have cell surface membranes, 70S ribosomes and a cellulose cell wall. The DNA of a

prokaryotic cell is circular and is found free in the cytoplasm rather than enclosed in a

nuclear envelope.

Identify and correct the factual error in the passage.

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

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

[Total: 3]

© UCLES 2024 9700/22/F/M/24 [Turn over

6 Fig. 6.1 is a simplified diagram representing a section through the human immunodeficiency virus
(HIV) particle that causes HIV / AIDS. The diagram shows the virus particle about to attach to
the cell surface membrane of a T-helper cell at a receptor protein called CD4. A second protein
(coreceptor) called CCR5 is also necessary for the virus particle to enter and then infect the
T-helper cell.

glycoprotein

viral envelope

X
HIV particle

viral nucleic acid

cell surface
membrane of
T-helper cell

CCR5 coreceptor CD4 receptor

protein protein

Fig. 6.1

(a) Identify structure X in Fig. 6.1.

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

(b) Explain how the ability of the immune system to resist the damaging effects of a pathogen is
affected by destruction of T-helper cells.

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

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

© UCLES 2024 9700/22/F/M/24

(c) Studies have shown that some individuals did not become infected with HIV even though
they were repeatedly exposed to the virus. Later discoveries indicated that these individuals
had a mutation in the gene for the CCR5 coreceptor protein.

Suggest how mutation of the gene for the CCR5 coreceptor protein provided protection
against HIV infection.

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

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

(d) The use of monoclonal antibodies against the CCR5 coreceptor protein (anti-CCR5) has
been shown to be effective in the treatment of HIV infection.

Outline how anti-CCR5 monoclonal antibodies can be synthesised in the laboratory using the
hybridoma method.

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

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

[Total: 8]

© UCLES 2024 9700/22/F/M/24

BLANK PAGE

The boundaries and names shown, the designations used and the presentation of material on any maps contained in this question paper/insert do not imply
official endorsement or acceptance by Cambridge Assessment International Education concerning the legal status of any country, territory, or area or any of its
authorities, or of the delimitation of its frontiers or boundaries.

Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.

To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.

© UCLES 2024 9700/22/F/M/24

* 0000800000001 *

, ,

Cambridge International AS & A Level

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* 2 8 1 1 2 0 2 2 7 8 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions October/November 2024

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Any blank pages are indicated.

DC (PB/FC) 336397/3
© UCLES 2024 [Turn over
* 0000800000002 *

DO NOT WRITE IN THIS MARGIN

2
, ,

1 The olive plant, Olea europaea, is grown in many parts of the world. The fruits of the plant (olives)
and the oil that can be obtained from the fruits (olive oil), provide food for humans.

Triglycerides are the main type of lipid in olive oil. They are synthesised in the olive plant from
glycerol and fatty acids.

Scientists can analyse samples of different olive oils to identify:

• the fatty acids used to synthesise triglycerides

• the composition of the different triglycerides present.

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(a) Table 1.1 shows some details of the five most common fatty acids found in samples of olive oil
produced by olive plants grown in different regions in Portugal.

Table 1.1

Key
C : D = number of carbon atoms : number of double bonds in the hydrocarbon chain
X = missing detail

percentage
fatty acid of total fatty C:D chemical structure
acid content

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oleic acid 55.0–83.0 18 : 1 CH3(CH2)7CH=CH(CH2)7X

palmitic acid 7.5–20.0 16 : ..... CH3(CH2)14X

linoleic acid 3.5–21.0 18 : ..... CH3(CH2)4(CH=CH)CH2(CH=CH)(CH2)7X

stearic acid 0.5–5.0 18 : ..... CH3(CH2)16X

palmitoleic acid 0.3–3.5 16 : ..... CH3(CH2)5CH=CH(CH2)7X

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(i) Table 1.1 shows the C : D values for oleic acid.

In Table 1.1, write the values for D for each of the four other fatty acids listed. [1]

(ii) In the first column of Table 1.1, draw a circle around each of the fatty acids that can be
described as saturated. [1]

(iii) State the detail of chemical structure, represented by X, which is missing from Table 1.1.

..................................................................................................................................... [1]
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(iv) The analysis of the triglycerides present in the different samples of olive oil showed that:

• there are many different triglycerides present in olive oil

• each olive oil is different in its composition, but the same few triglycerides are
present in all olive oils.

With reference to Table 1.1 and to the structure of triglycerides, suggest explanations for
these observations.

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

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

(b) Glycerol is soluble in water. Triglycerides are insoluble in water.

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Explain why water is a good solvent for some substances such as glycerol, but is a poor
solvent for substances such as triglycerides.

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

............................................................................................................................................. [2]
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(c) Phloem is the plant tissue responsible for the transport of organic substances, such as fatty
acids, from one area of a plant to another. The tissue is composed of more than one type
of cell.

Name the type of cell that forms the transport vessels of phloem tissue.

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

[Total: 8]
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4
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2 People who become infected with human immunodeficiency virus (HIV) are at risk of developing
HIV/AIDs, particularly if antiretroviral therapy (ART) is not available.

(a) In people infected with HIV, the use of ART also helps to reduce transmission of the virus to
uninfected people.

Outline two control methods, other than ART, that can be used to reduce the transmission
of HIV.

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

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

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

In people with HIV/AIDs, a serious lung disease known as pneumocystis pneumonia can result
from infection by an opportunistic pathogen known as Pneumocystis jirovecii.

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Fig. 2.1 shows P. jirovecii cells in one stage of their life cycle, as seen using a light microscope at
a magnification of ×600.

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0.4 μm

Fig. 2.1

(b) Define magnification.

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

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

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(c) Fig. 2.1 shows that P. jirovecii is a unicellular organism. Although the cells of many species of
bacteria are the same size as those of P. jirovecii, research concluded that the organism is a
eukaryote and is not a bacterium.

In 1988, analysis of ribosomal RNA (rRNA) resulted in P. jirovecii being classified as a fungus.

(i) Studies of the structure of P. jirovecii have identified that the cell wall is made of
polysaccharides such as chitin and 1,3‑β‑D‑glucan.

Explain why this feature helped scientists to confirm that P. jirovecii is not a bacterium.
DO NOT WRITE IN THIS MARGIN

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

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

(ii) Scientists have identified other features of the cell structure of P. jirovecii. Some of these
are listed in Table 2.1.

Complete each row of Table 2.1 so that the table shows:

• four structural features identified in P. jirovecii

•
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one function for each structural feature

• whether the structural feature is present (✓) or absent (✗) in bacterial cells.

Table 2.1

present (✓) or
structural feature of
function absent (✗) in
P. jirovecii
bacterial cells

ribosomes protein synthesis

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smooth endoplasmic
reticulum

Golgi body modification of proteins and lipids

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aerobic respiration

[3]

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(d) P. jirovecii can adhere (attach) to squamous epithelial cells of the alveoli and to the network
of fibrous proteins that support the alveolar wall, known as the extracellular matrix (ECM).
Examples of proteins in the ECM are elastin and collagen.

Adhesion (attachment) of P. jirovecii to alveolar epithelial cells and the ECM stimulates the
growth of its population.

(i) Cell surface glycoproteins known as gpA glycoproteins are essential in allowing
P. jirovecii cells to adhere to alveolar epithelial cells and ECM proteins.

Suggest how a gpA glycoprotein is able to adhere to alveolar epithelial cells and

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ECM proteins.

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

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

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(ii) One consequence of the pneumonia that results from P. jirovecii infection is a decrease
in the quantity of oxygen that is delivered to body tissues.

Explain why a severe P. jirovecii infection results in a decrease in the quantity of oxygen
that is delivered to body tissues.

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

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

..................................................................................................................................... [3]
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(e) P. jirovecii produces an enzyme known as 1,3‑β‑D‑glucan synthase. The enzyme catalyses
the synthesis of 1,3‑β‑D‑glucan.

The therapeutic drug caspofungin is a non‑competitive inhibitor of 1,3‑β‑D‑glucan synthase.

With reference to the mechanism of action of caspofungin, explain how the drug may be
useful to treat cases of pneumonia caused by P. jirovecii.

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

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

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

............................................................................................................................................. [5]

[Total: 17]
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3 During transcription, base pairing occurs between nucleotides.

Fig. 3.1 is a diagram to show complementary base pairing between a DNA nucleotide and an RNA
nucleotide.

Only the base pair is shown in molecular detail.

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H N O H N H
C
C C C C
N C N H N C H
ribose
N C C N
N H O
H

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Fig. 3.1

(a) Explain why Fig. 3.1 does not include any phosphodiester bonds.

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

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

(b) Identify and describe the DNA‑RNA nucleotide pair shown in Fig. 3.1.

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You may add labels and annotations to Fig. 3.1 if you wish.

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

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

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

[Total: 5]

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4 Adult stem cells are undifferentiated cells that are found in most animal tissues.

Adult stem cells can divide by mitosis throughout their lifespan to form identical stem cells
(self‑renewal) or to form cells that can differentiate into the functioning cells of that tissue.

(a) Mitosis is important for the repair of tissues.

Explain what is meant by repair of tissues.

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

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

(b) Uncontrolled cell division is a characteristic feature of tumour formation from a differentiated
cell.

Describe other features of tumour formation from a fully differentiated cell.

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

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

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

(c) Telomeres prevent loss of genes.

Adult stem cells have chromosomes with long telomeres.

Explain why long telomeres are an advantage to cells that carry out many cell cycles.
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...................................................................................................................................................

............................................................................................................................................. [2]
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10
, ,

Haematopoietic stem cells (HSCs) are adult stem cells that are located in the bone marrow of
bones. HSCs have a role in the formation of blood cells.

Fig. 4.1 is an outline summary showing the formation of some of the different types of blood cell
that can be formed from HSCs. The first stage is the division of HSCs to produce progenitor cells.
These cells are also able to divide by mitosis, but are not stem cells.

Key HSCs
= progenitor cells
self-
renewal

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CMP cells HSCs CLP cells

MEP cells GMP cells Pre-B cells Pre-T cells

immature megakaryocytes immature immature immature immature

red blood cells neutrophils monocytes B-lymphocytes T-lymphocytes

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mature mature
monocytes
B-lymphocytes T-lymphocytes
(T-helper and
immune T-killer cells)
mature red platelets mature response
blood cells neutrophils X

Fig. 4.1

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(d) With reference to Fig 4.1, explain why GMP cells, which are progenitor cells, cannot be
described as haematopoietic stem cells (HSCs).

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

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

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

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(e) Fig. 4.1 shows that monocytes differentiate into cell type X, which has a similar function
to neutrophils.

Name cell type X.

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

(f) Cell type Y shown in Fig. 4.1 releases molecules with antigen binding sites.

Name the molecules released by cell type Y.

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

(g) The differentiation of T‑lymphocytes begins in the bone marrow and continues in an organ
known as the thymus to produce fully differentiated T‑helper and T‑killer cells.

In the thymus, T‑lymphocytes that bind to self antigens are destroyed.

Explain why T‑lymphocytes that bind to self antigens need to be destroyed in the thymus.

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

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

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

[Total: 13]
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12
, ,

5 Malaria is an infectious disease caused by the protoctist, Plasmodium.

As part of its lifecycle, Plasmodium infects human red blood cells. Researchers can compare
haemoglobin from the red blood cells of a healthy person with haemoglobin from a person with
malaria.

(a) Throughout the world, most deaths from malaria are caused by P. vivax and P. falciparum.

Name one other species of Plasmodium that causes malaria.

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

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(b) In the laboratory, oxygen at different partial pressures can be bubbled through a solution of
haemoglobin to determine the percentage saturation of haemoglobin at each partial pressure.
A graph constructed from the results is known as an oxygen dissociation curve.

Fig. 5.1 is an oxygen dissociation curve for normal adult haemoglobin in humans.

100

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60
percentage
saturation of
haemoglobin
with oxygen 40

0 DO NOT WRITE IN THIS MARGIN

0 2 4 6 8 10 12 14
partial pressure
of oxygen / kPa

Fig. 5.1
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13
, ,

(i) In the experiment used to obtain the results shown in Fig. 5.1, the temperature and pH
were standardised.

Explain what the researchers would consider when deciding which temperature and pH
to use in the experiment.

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

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

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

(ii) Using a different, more rapid technique, researchers compared the haemoglobin
contained in red blood cells of a healthy person with the haemoglobin of a person with
malaria who had been infected with P. vivax.

By analysing the results, the researchers concluded that the oxygen dissociation curve
of a person with malaria would be shifted to the right.
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With reference to Fig. 5.1, explain how a shift to the right of the oxygen dissociation
curve would affect oxygen loading in the lungs, and unloading in respiring tissues, in a
person with malaria.

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

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

..................................................................................................................................... [3]
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* 0000800000014 *

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14
, ,

(c) A red blood cell that is infected with Plasmodium cannot carry out its function as effectively as
a normal red blood cell.

Describe how the size and structure of a red blood cell is related to its function, other than
the fact that it contains a very large number of haemoglobin molecules.

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

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

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

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[Total: 10]

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15
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6 The transport of water from the soil solution to the xylem of roots occurs by the apoplast and
symplast pathways. Mineral ions can be transported dissolved in water.

(a) Describe the transport of water from the soil solution to the endodermis of roots by the
apoplast pathway and explain why this pathway cannot continue at the endodermis.

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

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

............................................................................................................................................. [4]
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(b) Researchers investigated the mechanism of transport used for the uptake of potassium ions
(K+) into root epidermal cells at different concentrations of K+ in the soil solution.

Complete Table 6.1 to provide information about the two different transport mechanisms that
were identified by the researchers.

Table 6.1

membrane
net movement of ATP used
protein needed name of transport mechanism
K+ (yes or no)
(yes or no)
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against the
concentration
gradient

down the
concentration
gradient

[3]
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[Total: 7]

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16
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BLANK PAGE

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Permission to reproduce items where third‑party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.

To avoid the issue of disclosure of answer‑related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.

Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge
Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge.
ĬÍĊ®Ġ´íÈõÏĪÅĊàûµĄ×
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9700/22/O/N/24
Cambridge International AS & A Level
* 8 7 7 6 6 8 8 9 4 1 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions February/March 2023

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● 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 (PQ/CT) 313406/4
© UCLES 2023 [Turn over
2

1 (a) Table 1.1 lists cell structures that can be found in eukaryotic cells or prokaryotic cells. Some
of these cell structures can be found in both types of cell.

Complete the table using a tick (3) to show that the cell structure can be present in a particular
type of cell and a cross (✗) to show that the cell structure cannot be present.

Put a tick or a cross in every box.

The top row has been completed for you.

Table 1.1

cell structure eukaryotic cells prokaryotic cells

nucleus 3 ✗

Golgi body

circular DNA

70S ribosome
[2]

© UCLES 2023 9700/22/F/M/23

(b) All cells have a cell surface membrane. Fig. 1.1 shows a transmission electron micrograph of
part of two adjacent animal cells, cell 1 and cell 2.

cell 1
R

cell 2

×300 000

Fig. 1.1

In the space provided, draw a diagram of the region in the box labelled R on Fig. 1.1. Your
diagram should show the four dark lines.

Label the diagram to identify what is shown by the dark lines and each of the three spaces
between them.

space for diagram:

[3]
© UCLES 2023 9700/22/F/M/23 [Turn over
4

(c) Mitogens are short chains of amino acids that function as cell-signalling molecules. Mitogens
are released from secretory cells and travel in the blood to target cells, where the mitogens
bind to cell surface receptors. The target cells respond by progressing from the G1 phase to
the S phase of the mitotic cell cycle.

(i) Outline what happens in the G1 phase and S phase of the mitotic cell cycle.

G1 phase ...........................................................................................................................

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

S phase .............................................................................................................................

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

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

(ii) As a result of mutation, the production and release of mitogens into the blood can be
greatly increased.

Suggest a possible consequence for target cells of increased concentrations of mitogens

in the blood.

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

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

[Total: 8]

© UCLES 2023 9700/22/F/M/23

2 (a) Cysteine is an amino acid containing sulfur. Fig. 2.1 shows the structure of the molecule
formed by joining two cysteine molecules together.

SH
CH2 O H
H O H
C C N C C N
O H
H H CH2
SH

Fig. 2.1

Draw a circle around an R-group in the molecule shown in Fig. 2.1. [1]

(b) Goblet cells in the human gas exchange system produce proteins called mucins.

(i) The ends of mucin molecules contain many cysteine residues. Mucin strands are formed
by joining the ends of mucin molecules together through covalent bonds between
R-groups.

State the name of these covalent bonds.

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

(ii) Mucin strands are transported out of the goblet cells and then absorb water to form
mucus.

Suggest and explain how mucin strands are transported out of the goblet cells.

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

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

© UCLES 2023 9700/22/F/M/23 [Turn over

Cystic fibrosis is a genetic disease caused by a mutation in the human CFTR gene. This results in
mucus that is thicker than normal.

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

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

(d) Row 1 and row 2 of Table 2.1 show the DNA base sequences of part of the normal CFTR
allele and the same part of a mutated CFTR allele. The base sequences shown are for the
DNA strands used in the synthesis of RNA. When Table 2.1 is completed, row 3 will show the
base sequence of the RNA synthesised from the same part of the mutated CFTR allele.

Table 2.1

1 DNA base sequence

of part of the normal T A G T A G A A A C C A
CFTR allele
2 DNA base sequence
of part of the mutated T A G T A A C C A C A A
CFTR allele
3 RNA base sequence
synthesised from the
mutated CFTR allele

(i) The difference between the DNA base sequence in row 1 and the DNA base sequence
in row 2 of Table 2.1 is caused by a single gene mutation.

State the name of this type of gene mutation.

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

(ii) Row 1 and row 2 in Table 2.1 show the DNA strands used in the synthesis of RNA.

State the term used to describe the DNA strand that is used in the synthesis of RNA.

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

(iii) Complete Table 2.1 to show the missing bases in row 3. [1]

© UCLES 2023 9700/22/F/M/23

(iv) The normal CFTR allele is approximately 189 000 base pairs in length. The CFTR
polypeptide consists of only 1480 amino acids.

Explain the reasons for this difference between the number of base pairs and the number
of amino acids.

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

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

[Total: 13]

© UCLES 2023 9700/22/F/M/23 [Turn over

3 (a) Fig. 3.1 is a diagram of an area of phloem tissue from a transverse section through the stem
of a squash plant, Cucurbita pepo.

companion cell

Fig. 3.1

(i) Cell X and cell Y in Fig. 3.1 are sieve tube elements.

Explain why cell X and cell Y have very different appearances in this transverse section.

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

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

© UCLES 2023 9700/22/F/M/23

(ii) Sucrose is formed from the glucose synthesised by mesophyll cells in the leaves of C. pepo.

Explain how companion cells are involved in the transfer of sucrose into phloem sieve tubes.

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

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

(b) Hydrogen bonding is important in the movement of water in xylem.

(i) Explain how hydrogen bonding occurs between two water molecules.

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

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

(ii) Outline how hydrogen bonding is involved in water transport in the xylem of a plant stem.

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

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

© UCLES 2023 9700/22/F/M/23 [Turn over

(iii) Hydrogen bonding between water molecules gives water a relatively high latent heat of
vaporisation.

Suggest why it is important to plants that water has a high latent heat of vaporisation.

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

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

[Total: 13]

© UCLES 2023 9700/22/F/M/23

Question 4 starts on page 12.

© UCLES 2023 9700/22/F/M/23 [Turn over

4 Tuberculosis (TB), influenza and polio are examples of infectious diseases.

(a) (i) Explain what is meant by an infectious disease.

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

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

(ii) Name a species of organism that causes TB.

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

(b) Immunity can be described as artificial or natural and passive or active.

Name the type of immunity that a mother gives to her baby through breast milk.

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

(c) The influenza virus can mutate frequently to produce different strains of the virus. A new
vaccine is often necessary to stimulate the production of new antibodies to these new strains.

Explain why different antibodies need to be produced to give immunity to these new strains.

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

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

© UCLES 2023 9700/22/F/M/23

(d) Polio is a serious viral disease affecting young children. In 1996, polio caused paralysis in
more than 75 000 children across Africa. A long-term vaccination programme allowed the
World Health Organization (WHO) to declare that Africa was largely free of polio in 2020.

(i) Explain how vaccination programmes can help to control the spread of infectious
diseases, such as polio.

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

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

(ii) Antibiotics, such as penicillin, do not help to prevent the spread of viral diseases, such
as polio.

Explain why penicillin is not effective against viruses.

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

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

[Total: 11]

© UCLES 2023 9700/22/F/M/23 [Turn over

5 Pneumonia is a severe lung disease that can interfere with gas exchange. A person with
pneumonia can be connected to an ECMO machine. This machine performs the gas exchange
functions of the lungs.

A cannula (tube) is inserted into the right atrium and this takes blood to the ECMO machine. In the
ECMO machine, blood is passed firstly to an artificial pump and then to an oxygenator, where gas
exchange occurs. The blood is then warmed and returns by another cannula to the vena cava.

(a) Complete Fig. 5.1 to show how the ECMO machine is connected to the right atrium and to the
vena cava. Use a single line to represent each cannula.

artificial
pump

ECMO
machine
oxygenator

heater

Fig. 5.1
[1]

(b) In the oxygenator, a partially permeable membrane separates the blood from air that has
been enriched with extra oxygen.

(i) State the name of a structure in the gas exchange system that has the same function as
the partially permeable membrane of the oxygenator.

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

© UCLES 2023 9700/22/F/M/23

(ii) In the oxygenator, blood and oxygen-enriched air flow in opposite directions.

Suggest and explain how the oxygenator carries out the functions of gas exchange that
normally occur in the lungs.

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

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

tunica media

tunica externa

×16

Fig. 5.2

Explain how the structure of the tunica media in Fig. 5.2 is different from the structure of the
tunica media in a muscular artery and relate the difference to the function of the aorta.

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

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

© UCLES 2023 9700/22/F/M/23 [Turn over

(d) Some biologists investigated the transport of carbon dioxide in the blood of Caiman latirostris,
a type of reptile.

The biologists found that when C. latirostris respires:

• most of the carbon dioxide is converted into hydrogencarbonate ions in red blood cells
• the hydrogencarbonate ions combine with haemoglobin inside the red blood cells
• the hydrogencarbonate ions remain combined with haemoglobin until the blood reaches
the lungs.

(i) Explain why the physiology of C. latirostris requires carbonic anhydrase.

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

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

(ii) Explain why the physiology of C. latirostris does not require the chloride shift.

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

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

[Total: 10]

© UCLES 2023 9700/22/F/M/23

Question 6 starts on page 18.

© UCLES 2023 9700/22/F/M/23 [Turn over

6 (a) Collagen is the most common structural protein in vertebrates. Collagen provides the skin
with flexibility and strength.

Explain how the structure of a collagen fibre provides the skin with strength.

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

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

(b) The enzyme collagenase breaks down collagen. Collagenase has several important medical
uses, such as in the treatment of burnt skin.

Scientists investigated the effect of pH on the activity of collagenase at 37 °C.

The results of their investigation are shown in Fig. 6.1.

100

percentage 60
of maximum
activity 40

0
4.0 5.0 6.0 7.0 8.0 9.0 10.0
pH

Fig. 6.1

© UCLES 2023 9700/22/F/M/23

Explain why the activity of collagenase is lower at pH 8.0 than at the optimum pH.

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

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

[Total: 5]

© UCLES 2023 9700/22/F/M/23

BLANK PAGE

© UCLES 2023 9700/22/F/M/23

Cambridge International AS & A Level
* 3 8 8 8 9 4 9 2 2 6 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions May/June 2023

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● 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 (DE/AR) 316042/2
© UCLES 2023 [Turn over
2

1 The sinoatrial node (SAN) and the atrioventricular node (AVN) have an important role in the control
of the cardiac cycle. The timing of atrial and ventricular systole and diastole must be controlled so
that blood passes through the heart efficiently.

(a) Fig. 1.1 is a summary of blood flow through the right side of the heart during one cardiac
cycle. Three boxes in Fig. 1.1 are not complete.

Complete boxes 3, 5 and 7 in Fig. 1.1 using only the terms systole and diastole.

1 blood arrives at the heart in the superior vena cava and inferior vena cava

2 blood passes into the right atrium

3 atrial .................................................

ventricular ........................................

4 blood is forced into the right ventricle

5 atrial .................................................

ventricular ........................................

6 blood leaves the right ventricle to enter the pulmonary arteries

7 atrial .................................................

ventricular ........................................

Fig. 1.1
[2]

© UCLES 2023 9700/22/M/J/23

(b) Impulses sent out by the SAN pass to the AVN, where there is a short delay.

With reference to Fig. 1.1, explain why it is important for the control of the cardiac cycle that
there is a short delay at the AVN after impulses have been sent out by the SAN.

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

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

(c) Changes in blood pressure occur in the heart during the cardiac cycle. These changes cause
the opening and closing of the bicuspid and tricuspid (atrioventricular) valves and the aortic
and pulmonary (semilunar) valves.

Explain how blood pressure changes:

• cause the opening of the tricuspid valve

• cause the opening of the pulmonary valve
• help the flow of blood through the heart.

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

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

[Total: 7]

© UCLES 2023 9700/22/M/J/23 [Turn over

2 Fig. 2.1 is a photomicrograph of a longitudinal section (LS) through a root tip. Two different regions
are visible:

• the root apical meristem

• the root cap.

Cells in the root cap synthesise a gel-like, sticky secretion known as mucilage, which is important
in reducing friction between soil and the growing root. It is composed mainly of polysaccharides
and also contains some amino acids and enzymes.

root apical
meristem cells

1mm

root cap
cells

Fig. 2.1
© UCLES 2023 9700/22/M/J/23
5

(a) Describe three differences, visible in Fig. 2.1, between root apical meristem cells and root
cap cells.

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

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

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

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

3 ................................................................................................................................................

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

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

(b) Mucilage acts as a glue to bind tiny soil particles together, forming small clumps close to the
root. These small clumps help to maintain the soil water around the root tip and prevent the
loss of water.

With reference to the cohesive and adhesive properties of water, suggest and explain how
the formation of small clumps of soil helps to maintain the soil water around the root tip.

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

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

© UCLES 2023 9700/22/M/J/23 [Turn over

(c) Enzymes present in mucilage catalyse the breakdown of organic compounds in the soil. This
increases the presence of mineral ions in the soil.

State the term used to describe enzymes that act outside the cells that synthesise them.

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

(d) The polysaccharides and amino acids present in the mucilage are a source of nutrients for
soil microorganisms that live in the area surrounding the root. Some of these microorganisms
can break down soil compounds to release mineral ions.

(i) Explain what is meant by a polysaccharide.

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

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

(ii) The soil microorganisms use amino acids to synthesise proteins. All of the twenty
different amino acids that are present in proteins have the same general structure.

Draw the general structure of an amino acid in the space provided and use this drawing
to explain how it is possible to have many different amino acids.

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

..................................................................................................................................... [2]
© UCLES 2023 9700/22/M/J/23
7

(iii) Mineral ions are usually present in the soil in very low concentrations. The action of
mucilage enzymes and soil microorganisms can help to increase the presence of mineral
ions.

Root hair cells are specialised for the uptake of these mineral ions and for the absorption
of water from the soil.

Suggest and explain how the presence of mineral ions in the root hair cell can increase
the absorption of water by the root hair cells.

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

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

[Total: 14]

© UCLES 2023 9700/22/M/J/23 [Turn over

3 Cells of the immune system respond to the presence of non-self antigens.

(a) Outline the features of non-self antigens.

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

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

(b) Four different types of cells of the immune system are shown in Table 3.1.

Complete Table 3.1:

• use a tick (✓) if the description applies to the named cell of the immune system
• use a cross (✗) if the description does not apply.

Table 3.1

cell of the immune system

description of cell
B-lymphocyte plasma cell T-helper cell T-killer cell
able to go through a
number of cell cycles
(clonal expansion)
main role is to secrete
cytokine during an
immune response
present during a
primary immune
response to a virus
[4]

© UCLES 2023 9700/22/M/J/23

(c) The cell cycle can be divided into different parts.

Complete sentences A, B and C to provide more information about the mitotic cell cycle.

A The part of the cell cycle that occurs immediately after mitosis is

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

B The part of the cell cycle in which the S phase occurs is

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

C The main event that occurs during the S phase is

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

[Total: 10]

© UCLES 2023 9700/22/M/J/23 [Turn over

4 Trypanosoma brucei is a unicellular organism that causes the infectious disease known as
sleeping sickness. Insects known as tsetse flies pass on the organism from infected people to
uninfected people when male and female tsetse flies feed on human blood.

(a) Fig. 4.1 is a transmission electron micrograph of the form of T. brucei found in human blood.

1 μm

Fig. 4.1

(i) Draw an arrow on Fig. 4.1 to indicate the location in the cell where ribosomal RNA (rRNA)
and proteins are assembled to make ribosomal subunits. [1]

(ii) With reference to Fig. 4.1, explain how the structure labelled X provides evidence that
T. brucei is motile (able to move).

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

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

© UCLES 2023 9700/22/M/J/23

(iii) With reference to Fig. 4.1, explain whether T. brucei is a eukaryote or prokaryote.

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

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

(b) Malaria is an infectious disease caused by organisms belonging to the genus Plasmodium.

(i) State the term used to describe an organism that causes disease.

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

(ii) Name one of the species of Plasmodium that causes malaria.

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

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

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

[Total: 11]

© UCLES 2023 9700/22/M/J/23 [Turn over

5 Nucleotide and nucleoside analogues are therapeutic drugs that have a similar structure to
nucleotides or nucleosides of RNA and DNA.

A nucleoside is composed of a nitrogenous organic base (base) and a pentose sugar.

(a) The names of the bases present in RNA and DNA nucleotides can be abbreviated using a
single letter. These are shown in Table 5.1.

Complete Table. 5.1 by stating:

• the name of each base

• whether the base is a purine or pyrimidine
• whether the base is present
– only in an RNA molecule (write RNA in the table)
– only in a DNA molecule (write DNA in the table)
– in RNA and in DNA molecules (write the word both in the table).

Table 5.1

present in RNA,
base name of base purine or pyrimidine
DNA, or both
A
C
G
T
U
[4]

(b) Abacavir is an analogue drug used in the treatment of some viral diseases. It enters a cell
infected by a virus and is metabolised to the analogue carbovir triphosphate.

Fig. 5.1 shows the molecular structure of abacavir and carbovir triphosphate.

NH O
OH N
N HO O N
N P P O
HO N
N HO O O O N NH2
N NH2 P H
HO O

abacavir carbovir triphosphate

Fig. 5.1

© UCLES 2023 9700/22/M/J/23

Carbovir triphosphate can be inserted into an elongating polynucleotide chain instead of a

nucleotide. This interferes with the action of DNA polymerase during the synthesis of viral
DNA.

(i) With reference to Fig. 5.1, explain whether carbovir triphosphate will replace a purine or
a pyrimidine nucleotide in the elongating polynucleotide chain.

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

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

(ii) With reference to Fig. 5.1 and the action of DNA polymerase, suggest why the conversion
of abacavir to carbovir triphosphate increases the chance of the analogue being added
to the viral polynucleotide chain.

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

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

(iii) Suggest and explain how carbovir triphosphate interferes with the action of DNA
polymerase and how this may prevent the synthesis of viral DNA.

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

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

[Total: 11]

© UCLES 2023 9700/22/M/J/23 [Turn over

BLANK PAGE

© UCLES 2023 9700/22/M/J/23

6 The Weibel Lung model was developed after an extensive study of the gas exchange system. The
model includes detailed measurements of airway diameters (lumen diameters of the airways). In
the model, different parts of the gas exchange system are identified with a generation number, as
outlined in Fig. 6.1.

airway generation number

0
trachea

1
X
2

3
bronchioles 4
5

terminal bronchioles 16
17

respiratory bronchioles
18
19
20
alveolar ducts 21
22
alveolar sacs alveoli 23

Fig. 6.1

(a) The Weibel Lung model describes how each airway divides into two.

Name the airways in generation 1, labelled X in Fig. 6.1, that branch from generation 0.

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

(b) The airways are well supplied with blood. However, the airways from generation 0 to
generation 16, shown in Fig. 6.1, are not able to carry out gas exchange.

Suggest why the airways from generation 0 to generation 16 are not able to carry out gas
exchange.

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

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

© UCLES 2023 9700/22/M/J/23 [Turn over

(c) High-resolution computed tomography (HRCT) is an imaging technique that is used to obtain
measurements of airway diameters in people with a pulmonary (lung) disease. Regular,
repeated imaging must be avoided because it involves exposure to harmful radiation.

Scientists researched the use of a different technique, HP gas MRI, that does not involve
harmful radiation. Two types of MRI image, known as projection and multi-Slice, were used to
obtain measurements of airway diameters.

Fig. 6.2 shows the results of the HP gas MRI study compared with the Weibel Lung model,
for generations 0 to 5. The Weibel Lung model was used as a standard reference for airway
diameters.

2.0

1.8

1.6

1.4

1.2
airway diameter
/ cm 1.0

0.8

0.6

0.4

0.2

0.0
0 1 2 3 4 5
Key airway generation
projection
multi-Slice
Weibel Lung model

Fig. 6.2

© UCLES 2023 9700/22/M/J/23

(i) State the relationship shown in Fig. 6.2 between airway diameter and airway generation
for the Weibel Lung model data.

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

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

(ii) With reference to the data in Fig. 6.2, explain whether HP gas MRI could be a useful
alternative to HRCT in obtaining airway diameter measurements.

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

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

[Total: 7]

© UCLES 2023 9700/22/M/J/23

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© UCLES 2023 9700/22/M/J/23

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© UCLES 2023 9700/22/M/J/23

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© UCLES 2023 9700/22/M/J/23

Cambridge International AS & A Level
* 4 0 1 1 5 8 4 9 4 9 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions October/November 2023

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Any blank pages are indicated.

DC (CE/CT) 323065/3
© UCLES 2023 [Turn over
2

1 During interphase and mitosis of the cell cycle, the chromosomes within a cell go through a
number of changes. Each chromosome is composed of DNA complexed with proteins.

(a) In interphase, individual chromosomes are too diffuse (long and thin) to be visible using a
microscope. In this stage, the chromosomal material is known as chromatin.

State the term used to describe the proteins that are complexed with DNA and form part of
chromatin.

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

(b) When viewed through a microscope, a chromosome is most clearly visible during the
metaphase stage of mitosis.

Complete Fig. 1.1 to produce a labelled diagram of the metaphase stage of mitosis in an
animal cell with two chromosomes.

Fig. 1.1
[3]

• from the start of the S phase to the end of interphase

• during prophase of mitosis.

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

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

[Total: 7]
© UCLES 2023 9700/22/O/N/23
3

2 Keratin is the structural protein in feathers of birds. Keratin polypeptides are composed of a high
proportion of cysteine amino acids, which have sulfur-containing R groups.

Keratin polypeptides form filaments. The two main types of keratin in feathers are α-keratin, which
consists of many α-helices, and β-keratin, consisting of many β-pleated sheets.

(a) Keratin can be classified as α-keratin or β-keratin based on a study of protein structure.

Suggest the level of protein structure used to classify a protein as α-keratin or β-keratin.

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

(b) Protease enzymes hydrolyse proteins. Many proteases are able to hydrolyse more than one
type of protein.

Suggest why it is possible for a protease to act on different types of protein.

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

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

Feathers are not easily degraded (broken down) because keratin is a very stable protein.

Suggest features of keratin structure that contribute to its stability.

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

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

© UCLES 2023 9700/22/O/N/23 [Turn over

Keratinases are used to degrade the large quantities of waste feathers from chickens and turkeys
that are processed in the food industry. The products of feather degradation can be used in animal
feed.

Scientists investigated whether three different keratinases, K12, A22 and P3, were suitable as
industrial enzymes. These enzymes were extracted from three different soil bacteria.

The effects of temperature and pH on the activity of each keratinase were investigated.

The results are shown in Fig. 2.1 and Fig. 2.2.

Key
K12 =
A22 =
P3 =
100

60
relative activity
/%
40

0
20 30 40 50 60 70 80
temperature / °C

Fig. 2.1

100

60
relative activity
/%
40

0
5.0 6.0 7.0 8.0 9.0 10.0
pH

Fig. 2.2

© UCLES 2023 9700/22/O/N/23

(d) To degrade feather waste from industry, it is an advantage to use keratinases that show at
least 60% relative activity in conditions where temperature and pH can vary widely.

Table 2.1 shows, for each keratinase, the working range of temperature and pH where at
least 60% relative activity is obtained.

Use Fig. 2.1 and Fig. 2.2 to complete Table 2.1 and use the completed table to:

• name the keratinase that has the widest working range of temperature
• name the keratinase that has the widest working range of pH.

Table 2.1

temperature range with at pH range with at

keratinase
least 60% relative activity / °C least 60% relative activity
K12 41–63

A22 6.0–9.0

P3 29–56 5.3–7.5

Keratinase with a relative activity of at least 60% that has:

• the widest working range of temperature ...................................

• the widest working range of pH ...................................

[4]

(e) Some detergents contain proteases to remove stains from clothes. These enzymes have a
high relative activity in alkaline conditions.

The scientists reported that K12 and A22 could be suitable for use in the detergent industry.

With reference to Fig. 2.1 and Fig. 2.2, discuss the advantages and disadvantages of using
K12 and A22 in the detergent industry.

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

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

[Total: 12]

© UCLES 2023 9700/22/O/N/23 [Turn over

3 The liver receives blood from the hepatic artery and from the hepatic portal vein. The hepatic
portal vein transports blood from the digestive system.

Hepatocytes are the main cell type of the liver. They have a wide range of functions, including:

• the synthesis of triglycerides and plasma proteins

• detoxifying waste
• energy storage.

(a) The hepatic artery branches from the main artery that transports blood from the heart.

Name the main artery that transports blood to the hepatic artery.

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

(b) Blood arriving at the liver enters specialised blood vessels known as sinusoids.

Fig. 3.1 is a diagram of part of a sinusoid and surrounding hepatocytes. A second type of cell
found in the liver, a Kupffer cell, is also shown.

Kupffer cells are phagocytic cells of the immune system.

Kupffer cell large gap between

endothelial cells

sinusoid

hepatocyte

Fig. 3.1

(i) Suggest one advantage of having large gaps between the endothelial cells of the
sinusoid, as shown in Fig. 3.1.

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

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

© UCLES 2023 9700/22/O/N/23

(ii) In addition to removing bacteria present in the blood inside the sinusoid, Kupffer cells are
also able to remove old or damaged red blood cells.

Describe the mode of action of a Kupffer cell in removing and breaking down a damaged
red blood cell.

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

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

© UCLES 2023 9700/22/O/N/23 [Turn over

The peroxisome shown in Fig. 3.2 is a spherical organelle bound by a single membrane. It
carries out a variety of enzyme-catalysed metabolic reactions, including detoxification. Some
of these reactions require oxygen.

peroxisome

glycogen
granules

lipid droplet

Fig. 3.2

(i) Describe the evidence visible in Fig. 3.2, apart from the presence of a peroxisome, that
indicates some of the functions of a hepatocyte.

Add labels to Fig. 3.2 to identify the location of any cell structures, if not already labelled,
that are part of your evidence.

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

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

© UCLES 2023 9700/22/O/N/23

(ii) The mitochondria in Fig. 3.2 are larger than the peroxisome.

State one other difference, visible in Fig. 3.2, between a peroxisome and a
mitochondrion.

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

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

(iii) Some of the enzymes used within mitochondria can be synthesised by the organelle.
Peroxisomes cannot synthesise any of the enzymes that they contain.

Suggest why a mitochondrion can synthesise enzymes, but a peroxisome cannot

synthesise enzymes.

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

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

(iv) One of the enzymes present in peroxisomes is catalase. This enzyme catalyses the
breakdown of hydrogen peroxide to harmless products.

Suggest why it is useful to the cell for this reaction to take place within peroxisomes.

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

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

[Total: 14]

© UCLES 2023 9700/22/O/N/23 [Turn over

4 The alveoli of the lungs are the main gas exchange surface in humans.

(a) Explain how blood flow through the alveolar capillaries helps to maintain steep diffusion
gradients for gas exchange.

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

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

(b) Ventilation of the lungs is the process of inhalation and exhalation. Ventilation helps to
maintain steep diffusion gradients.

Explain the role of elastic fibres in the alveolar wall during ventilation.

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

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

(c) Some cells in the alveolar wall are specialised to secrete surfactant to prevent collapse of
the alveoli at the end of exhalation. In these cells, surfactant is stored in membrane-bound
organelles known as lamellar bodies. Surfactant is a mixture of lipids, mainly phospholipids,
and some proteins.

A protein known as ATP-binding cassette transporter A3 (ABCA3) is needed to move

surfactant phospholipids into lamellar bodies from the surrounding cytosol (fluid part of
cytoplasm).

Suggest and explain the features of protein ABCA3 that make it suited to its function.

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

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

© UCLES 2023 9700/22/O/N/23

(d) The gene ABCA3 codes for protein ABCA3. The gene is 80 kb (80 000 base pairs) long and is
composed of introns and exons. Protein ABCA3 is composed of 1704 amino acids.

(i) Fig. 4.1 shows the flow of genetic information in the production of ABCA3.

gene ABCA3

X ...............................................

primary transcript RNA

messenger RNA (mRNA)

Y ...............................................

polypeptide ABCA3

protein ABCA3

Fig. 4.1

Complete Fig. 4.1 to name the processes occurring at X and Y. [2]

(ii) A triplet of bases codes for one amino acid. This fact only partly explains how the activity
of gene ABCA3, which is 80 kb long, can result in the protein ABCA3, which is only 1704
amino acids long.

Suggest other reasons to explain the difference in the number of base pairs in gene
ABCA3 compared with the number of amino acids in protein ABCA3.

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

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

[Total: 12]

© UCLES 2023 9700/22/O/N/23 [Turn over

5 Tuberculosis (TB) is an infectious disease caused by a bacterium. In the majority of people, only
the lungs are affected.

In most cases, the transmission of TB from an infected person to an uninfected person involves
Mycobacterium tuberculosis. A different species of bacterium is involved in the transmission of TB
from cattle, such as dairy cows, to humans.

(a) Name the species of bacterium causing the transmission of TB from dairy cows to humans.

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

(b) In some areas, cattle cannot be regularly tested or treated for TB. In these areas, milk and
dairy products from infected dairy cattle may enter the human food chain.

Outline a control measure that can be taken to protect people that consume milk and dairy
products from these infected cattle.

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

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

A few cases of transmission of TB from people to animals have been reported.

Explain the most likely mode of transmission of TB from an infected person to an animal.

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

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

(d) In most people, the response of the immune system to the infection of lung tissue by
M. tuberculosis can prevent the spread of the bacterium to other organs of the body. The
bacterium is contained in the lungs in a dormant state. This is known as latent TB.

Outline the treatment that is used to kill M. tuberculosis in latent TB infections.

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

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

© UCLES 2023 9700/22/O/N/23

(e) M. tuberculosis can spread in the blood and lymph to other organs in the body.

In very rare cases, a disease known as mycotic aneurysm can be caused by infection of the
arterial wall, particularly in elastic arteries. The damage caused by the pathogen can lead to a
rupture (bursting) of the artery.

With reference to the structure of the wall of elastic arteries, suggest how damage caused by
M. tuberculosis infection can lead to the rupture of the artery.

You may draw a diagram if you wish.

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

Space for diagram

[3]

[Total: 9]

© UCLES 2023 9700/22/O/N/23 [Turn over

6 Water that is absorbed from the soil solution by the roots of a plant enters xylem vessels and is
transported to the leaves and buds.

Fig. 6.1 shows four important requirements for the efficient transport of water from the roots to the
leaves of a plant.

xylem vessels must

be able to cope with
tension needs to the tensions created
be created in by the movement of
xylem vessels water

requirements for
the efficient
transport of water

water in xylem vessels there should be

must be in continuous, minimum resistance
unbroken columns to the flow of water

Fig. 6.1

(a) Name the specialised cells that are arranged end to end to form xylem vessels.

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

(b) Explain how tension is created in the xylem vessels.

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

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

© UCLES 2023 9700/22/O/N/23

(c) Fig. 6.1 highlights how the structure of xylem vessels must be related to their function. This
means that during the development of xylem vessels changes need to occur to the cells
forming the vessels.

(i) The walls of the cells forming the xylem vessel walls become lignified during development.

Explain how this feature is important for the efficient transport of water.

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

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

(ii) During the development of xylem vessels, the end walls of the cells forming the vessels
break down. This contributes to minimising resistance to the flow of water.

Describe one other main change that needs to occur to these cells so that their structure
becomes suited to their function.

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

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

[Total: 6]

© UCLES 2023 9700/22/O/N/23

BLANK PAGE

© UCLES 2023 9700/22/O/N/23

Cambridge International AS & A Level
* 6 9 5 9 5 8 6 3 1 6 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions February/March 2022

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● 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 (LK/CT) 303956/4
© UCLES 2022 [Turn over
2

Question 1 starts on page 3.

© UCLES 2022 9700/22/F/M/22

1 (a) Table 1.1 shows three of the processes by which substances in solution can move across cell
membranes. It also lists five statements that may apply to each of these three processes.

Complete Table 1.1 to show which of the statements apply to each of the three processes
shown.

Use a tick (3) to show that the statement applies or a cross (✗) to show that the statement
does not apply.

Each box must contain a tick or a cross.

The first row has been completed for you.

Table 1.1

process
statement active facilitated simple
transport diffusion diffusion

movement of oxygen into a red blood cell ✗ ✗ 3

occurs in both animal and plant cells

uses carrier proteins

movement of non-polar molecules between the fatty

acid tails of the phospholipid molecules

movement of ions down a concentration gradient

[4]

© UCLES 2022 9700/22/F/M/22 [Turn over

(b) Fig. 1.1 is a simplified diagram representing a transverse section of part of a young root. The
diagram is not to scale.

(i) On Fig. 1.1 draw a label line and label with the letter C to identify the Casparian strip. [1]

soil particles xylem vessel

root hair cell

key
pathway for the movement of water

Fig. 1.1

(ii) Root hairs measure approximately 5 μm in diameter and 500 μm in length.

Explain how this adapts root hairs for the absorption of water.

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

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

(iii) Name the pathway for the movement of water shown by the arrows in Fig. 1.1.

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

© UCLES 2022 9700/22/F/M/22

(c) Water enters the xylem vessels shown in Fig. 1.1.

Explain how water moves up the xylem vessels to the leaves in a continuous column.

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

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

[Total: 10]

© UCLES 2022 9700/22/F/M/22 [Turn over

2 (a) Fig. 2.1 shows a cell at one of the main stages of mitosis in the mitotic cell cycle.

Fig. 2.1

(i) Name the stage of mitosis shown in Fig. 2.1.

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

(ii) Fig. 2.2 shows the cell in Fig. 2.1 at the start of cytokinesis.

Complete Fig. 2.2 to show the daughter chromosomes in each nucleus.

nuclear
envelopes
forming

Fig. 2.2

[2]

© UCLES 2022 9700/22/F/M/22

(b) State the role of telomeres during DNA replication.

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

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

(c) Multiple myeloma is a type of cancer in the bone marrow where some of the stem cells start
to produce abnormal blood cells.

• One treatment is to collect stem cells from the bone marrow of the person with multiple
myeloma. Healthy stem cells are isolated and grown in the laboratory.

• Radiation is then used to destroy all stem cells and cancerous cells in the bone marrow.

• Finally, large numbers of the healthy stem cells grown in the laboratory are returned to
the bone marrow.

Suggest the role of stem cells in this treatment of multiple myeloma.

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

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

[Total: 7]

© UCLES 2022 9700/22/F/M/22 [Turn over

3 (a) Enzymes are polymers of amino acids.

Complete Fig. 3.1 to show the general structure of an amino acid.

C C N
O
H

Fig. 3.1

[1]

(b) When bananas are peeled, the exposed tissue gradually turns brown in the presence
of oxygen in the air. This is due to an enzyme called catechol oxidase, which acts on the
substrate catechol. Catechol and catechol oxidase are present in the banana tissue.

The overall reaction is shown in Fig. 3.2.

catechol oxidase
catechol melanin
(colourless) oxygen (brown)

Fig. 3.2

A student investigated how the concentration of catechol oxidase affects the rate of this
reaction. All other variables were kept constant throughout the investigation.

For each concentration of catechol oxidase used, the student mixed catechol oxidase solution
with catechol and recorded the time taken for the mixture to reach a standard brown colour.

The rate of reaction, R, for each concentration of catechol oxidase used was then calculated
using the formula:
1
R=
time to reach standard brown colour in minutes
(i) Calculate the rate of reaction when the standard brown colour was reached in
2 minutes 30 seconds.

rate of reaction = ............................................... min–1 [1]

© UCLES 2022 9700/22/F/M/22

(ii) Fig. 3.3 is a graph showing the results of the investigation.

0.8

0.7

0.6

0.5
rate of
reaction 0.4
/ min–1
0.3

0.2

0.1

0.0
0 2 4 6 8 10
percentage concentration of catechol oxidase

Fig. 3.3

State how the results shown in Fig. 3.3 show that substrate was in excess at all
concentrations of catechol oxidase tested.

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

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

© UCLES 2022 9700/22/F/M/22 [Turn over

(c) The student carried out a further experiment to investigate how the concentration of catechol
affects the initial rate of reaction. All other variables were kept constant throughout this
investigation.

Fig. 3.4 is a graph showing the effect of varying the concentration of catechol on the initial
rate of reaction.

10.0

9.0

8.0

7.0

6.0
initial rate
of reaction 5.0
/ min–1
4.0

3.0

2.0

1.0

0.0
0.00 0.20 0.40 0.60 0.80 1.00 1.20
catechol concentration / mol dm–3

Fig. 3.4

(i) Explain the shape of the curve shown in Fig. 3.4.

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

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

© UCLES 2022 9700/22/F/M/22

(ii) Use Fig. 3.4 to calculate the value of the Michaelis–Menten constant (Km) for the reaction
between catechol oxidase and catechol.

Km = ........................................... mol dm–3 [1]

(iii) Methylcatechol has a similar shape to catechol. Catechol oxidase can also use
methylcatechol as a substrate.

The Km value for the reaction using methylcatechol as the substrate was found to be
much lower than the Km value for the reaction using catechol as the substrate, when the
reactions were carried out under the same conditions.

State what these Km values indicate about the relationship between the enzyme and the
two substrates.

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

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

[Total: 8]

© UCLES 2022 9700/22/F/M/22 [Turn over

4 Tuberculosis (TB) is a major cause of ill health worldwide.

(a) State the name of a bacterium that causes TB in humans.

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

(b) Fig. 4.1 is a scanning electron micrograph of bacteria that cause TB.

X
Y

magnification ×21 000

Fig. 4.1

Calculate the actual length of the bacterial cell shown in Fig. 4.1, along the line X–Y.

Write the formula you will use in the box.

Give your answer in micrometres (μm) to two significant figures.

formula

actual length = ......................................................... μm

[2]

State two other structural features that would identify a cell as prokaryotic.

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

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

© UCLES 2022 9700/22/F/M/22

(d) The World Health Organization (WHO) Global Tuberculosis Report for 2019 published data
on the estimated number of deaths from TB and HIV / AIDS in 2018. All deaths of people from
TB who were infected with HIV were also counted as deaths of people with HIV / AIDS.

Fig. 4.2 shows these data. The dark grey boxes show the estimated number of deaths of
people from TB who were also counted as deaths of people with HIV / AIDS.

deaths of people with

not infected with HIV
from TB HIV / AIDS

deaths of people from TB

with HIV / AIDS

0.00 0.25 0.50 0.75 1.00 1.25 1.50

millions of deaths in 2018

Fig. 4.2

A student used the data in Fig. 4.2 to predict that measures to control the spread of HIV will
decrease the number of deaths from TB.

Discuss whether the data in Fig. 4.2 support this prediction.

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

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

© UCLES 2022 9700/22/F/M/22 [Turn over

(e) In healthy people, the number of T-helper cells ranges from 500 to 1200 cells per cm3 of
blood. In untreated people infected with HIV, the number of T-helper cells can decrease to
below 200 cells per cm3 of blood.

Explain how a low number of T-helper cells makes it more likely that untreated people infected
with HIV will die if they are also infected with TB.

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

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

[Total: 11]

© UCLES 2022 9700/22/F/M/22

5 Control of heartbeat is myogenic. This means the electrical activity controlling the rhythm of a
regular heartbeat begins in the heart muscle itself.

Atrial fibrillation (AF) is an abnormal heart rhythm that causes rapid and irregular contractions of
the atria. Untreated cases of AF can lead to a stroke.

(a) A stroke is caused when a small blood clot, often forming in the left atrium, is carried by the
blood to the brain where it blocks a small artery and leads to brain damage.

(i) List all of the structures through which a blood clot in the left atrium must travel to reach
the blood vessels supplying the brain.

The structures must be listed in the correct sequence.

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

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

(ii) Explain why blocking a small artery in the brain leads to brain damage.

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

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

(b) A common cause of AF is when a small group of muscle cells in the wall of the left atrium
starts to send out electrical impulses to the surrounding heart muscle cells.

Explain how the control of heartbeat by the sinoatrial node can be disrupted by AF, resulting
in rapid and irregular atrial contractions.

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

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

© UCLES 2022 9700/22/F/M/22 [Turn over

Fig. 5.1 is a diagram representing the exchange of oxygen and carbon dioxide between a red
blood cell in a capillary and a respiring cell. Some of the reactions that take place in the red
blood cell are also shown. The diagram is not drawn to scale.

capillary wall
basement
endothelial cells
membrane

respiring cell

red blood cell

CO2 enzyme X
CO2 + H2O H2CO3
carbonic acid Z

4O2
HCO3– + H+
hydrogencarbonate
ion

4O2 + Y HbO8 + H+
Z
oxyhaemoglobin

Fig. 5.1

(i) Identify enzyme X and molecule Y in Fig. 5.1.

X ........................................................................................................................................

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

(ii) The hydrogencarbonate ions shown in Fig. 5.1 leave the red blood cell and are replaced
by chloride ions.

State why it is necessary for chloride ions to enter the red blood cell as hydrogencarbonate
ions leave.

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

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

© UCLES 2022 9700/22/F/M/22

(d) Identify the aqueous environment, labelled Z in Fig. 5.1, that surrounds the respiring cell.

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

(e) Oxygen and carbon dioxide are also exchanged between blood capillaries and alveoli in the
lungs.

The gas exchange system has specialised cells to prevent harmful microscopic particles that
are present in inhaled air from reaching the alveoli.

These particles are associated with many respiratory diseases.

Explain how specialised cells in the gas exchange system prevent harmful microscopic
particles from reaching the alveoli.

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

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

[Total: 12]

© UCLES 2022 9700/22/F/M/22 [Turn over

6 Fig. 6.1 is a diagram showing the structure of part of a DNA molecule.

adenine E

key

one hydrogen bond

Fig. 6.1

(a) (i) Identify structure E and structure F in Fig. 6.1.

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

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

(ii) On Fig. 6.1 draw a circle around one nucleotide. [1]

(iii) State the name of the covalent bond that links two nucleotides together.

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

© UCLES 2022 9700/22/F/M/22

(b) Fig. 6.2 shows the RNA base sequence of a short length of primary transcript.

Complete Fig. 6.2 by writing the DNA base sequence of the template strand used to form the
primary transcript.

DNA base sequence used to

form the primary transcript

primary transcript GGU GCU AA U CUA

Fig. 6.2
[1]

(c) In eukaryotic cells, the primary transcript is modified to form mRNA.

Explain how the primary transcript is modified to form mRNA.

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

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

(d) The mRNA strand is translated at the ribosome to form a polypeptide.

Describe how the process of translation results in the formation of a polypeptide.

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

............................................................................................................................................. [5]

[Total: 12]
© UCLES 2022 9700/22/F/M/22
20

BLANK PAGE

© UCLES 2022 9700/22/F/M/22

Cambridge International AS & A Level
* 2 6 8 2 7 9 7 5 8 1 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions May/June 2022

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages.

DC (CE/SG) 302736/1
© UCLES 2022 [Turn over
2

1 Epithelial cells in the small intestine have cell structures known as microvilli. The microvilli of these
cells are found only on the surface that borders the gut lumen.

Fig. 1.1 shows images of microvilli of intestinal epithelial cells. These images have been obtained
using a scanning electron microscope and a transmission electron microscope.

Fig. 1.1A is at a different magnification to Fig. 1.1B.

A B

Fig. 1.1

(a) With reference to Fig. 1.1, state how it is possible to distinguish between a scanning electron
micrograph and a transmission electron micrograph.

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

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

(b) The approximate length of a microvillus is 1 μm.

Outline the method you would use to estimate the magnifications of the images shown in
Fig. 1.1.

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

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

© UCLES 2022 9700/22/M/J/22

(c) One role of an intestinal epithelial cell is the absorption of glucose from the gut lumen into the
circulatory system. This involves different membrane transport proteins.

The events occurring in an intestinal epithelial cell during the absorption of glucose are
summarised in Fig. 1.2.

not to scale

glucose
gut
lumen
tissue capillary
K+ fluid

glucose
Na+
Na+

Fig. 1.2

• Sodium ions (Na+) are removed from the cell by active transport through a transport
protein known as a sodium-potassium (Na+ / K+) pump.

• This decreases the concentration of Na+ in the cell compared to the gut lumen.

• Glucose molecules are cotransported with Na+ into the cell from the gut lumen.

• Glucose molecules are transported out of the cell into the tissue fluid down a concentration
gradient.

(i) Active transport involves water-soluble substances, such as Na+ and K+, and the use of
ATP to provide the energy needed for their transport through carrier proteins.

Outline other features of active transport.

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

..................................................................................................................................... [2]
© UCLES 2022 9700/22/M/J/22 [Turn over
4

(ii) Glucose molecules enter the cell through a membrane protein.

Suggest why glucose molecules need to be cotransported with Na+ when it enters the
cell through the membrane protein.

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

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

(iii) Explain how microvilli increase the uptake of glucose into an intestinal epithelial cell.

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

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

(d) Stem cells are also located in the wall of the small intestine. These cells divide by mitosis
continuously.

Suggest and explain the importance of mitosis by stem cells in the small intestine.

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

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

[Total: 13]

© UCLES 2022 9700/22/M/J/22

2 Cholera is a life-threatening and infectious disease caused by the bacterium Vibrio cholerae. One
of the symptoms of the disease is severe diarrhoea.

V. cholerae O1 and V. cholerae O139 are the two forms of the pathogen that are associated
with cholera epidemics (large outbreaks). These two forms have different antigens that can be
detected.

(a) If an outbreak of cholera is suspected but not confirmed, a standard home treatment for
diarrhoeal diseases can be used immediately to help prevent severe illness as a result of
dehydration. If cholera is the cause of the disease, this standard treatment also helps to
prevent a larger outbreak of the disease.

(i) Outline the standard treatment that can be used for suspected cholera cases.

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

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

(ii) Suggest and explain why this treatment can help to prevent a larger outbreak of cholera.

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

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

© UCLES 2022 9700/22/M/J/22 [Turn over

(b) Rapid diagnostic testing (RDT) can be used to diagnose cholera by detecting the presence of
V. cholerae. One type of RDT involves using a dipstick that contains mobile and immobilised
monoclonal antibodies.

Monoclonal antibodies (mAbs) are specific in their action.

Fig. 2.1 shows a simplified diagram of an RDT dipstick that can be used to distinguish between
V. cholerae O1 and V. cholerae O139. A faecal sample from a person with suspected cholera
is collected and added to a reagent solution to form the test mixture.

area where dipstick can be held

4 control area

3 test area containing immobilised monoclonal antibody that

binds antigen-antibody complex O1

2 test area containing immobilised monoclonal antibody that

binds antigen-antibody complex O139

direction
of flow of 1 area containing two different mobile monoclonal antibodies:
test • anti-O1 antibody
mixture • anti-O139 antibody
area where dipstick is inserted into the test mixture

Fig. 2.1

The test mixture moves up the dipstick through area 1. The mobile monoclonal antibodies are
attached to tiny gold particles. If these antibodies collect in test area 2 or 3, a coloured band
becomes visible.

A coloured band that becomes visible in area 4 confirms that the test strip is working and that
the results are valid.

(i) Explain how the structure of the monoclonal antibodies in the dipstick allows them to be
specific in their action.

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

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

© UCLES 2022 9700/22/M/J/22

(ii) Fig. 2.2 shows the results for samples taken from two different people, A and B, who are
suspected of having cholera.

4 4

3 3

2 2

1 1

person A person B

Fig. 2.2

With reference to Fig. 2.2, state and explain the conclusions that can be drawn from the
results of the RDT dipsticks for each person.

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

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

© UCLES 2022 9700/22/M/J/22 [Turn over

(c) Table 2.1 shows the results of an investigation to evaluate the effectiveness of an RDT
dipstick in diagnosing cholera.

Samples taken from 156 people were tested using a dipstick and compared to the results
obtained by culturing the pathogen in a laboratory for accurate identification.

Table 2.1

number of test results

using culture techniques using dipstick
(to obtain accurate
identification) correct diagnosis incorrect diagnosis
positive results for cholera 102 97 5
negative results for cholera 54 32 22

(i) With reference to Table 2.1, calculate the percentage chance of an RDT dipstick correctly
confirming that a person with cholera has the disease.

[1]

(ii) Using an RDT dipstick to diagnose cholera is much cheaper than culturing the pathogen
and requires less technical skill.

Suggest one additional advantage of using an RDT dipstick, rather than culture
techniques, to diagnose cholera.

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

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

[Total: 11]

© UCLES 2022 9700/22/M/J/22

3 Hummingbirds are the smallest of birds and are found in the Americas. Some species migrate
hundreds of kilometres between warmer overwintering areas and summer breeding grounds. Like
mammals, birds maintain a constant body temperature.

Hummingbirds have a high requirement for sugars because they have a very high metabolic rate.
Fig. 3.1 shows a hummingbird feeding on nectar, one of their main food sources.

Fig. 3.1

(a) Nectar is a sugary liquid containing mainly sucrose, fructose and glucose.
Sucrose has the molecular formula C12H22O11. Fructose and glucose each have the molecular
formula C6H12O6.

State two differences between sucrose and fructose, other than the number of carbon,
hydrogen and oxygen atoms present.

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

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

© UCLES 2022 9700/22/M/J/22 [Turn over

(b) In preparation for migration, sugars need to be converted to triglycerides to function as energy
reserves. Hummingbirds can double their body mass during this time.

(i) Fig. 3.2 shows the structural formula of one type of storage triglyceride. The triglyceride
has two types of fatty acid residue, palmitate and oleate.

H H H
H C C C H
O O O
C O C O C O
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H C H H C H C
H C H H C H C
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H C H H C H H C H
H H C H H C H
H C H H C H
H H

palmitate oleate

Fig. 3.2

Outline the features of the molecular structure of the triglyceride shown in Fig. 3.2.

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

..................................................................................................................................... [3]
© UCLES 2022 9700/22/M/J/22
11

(ii) In hummingbirds, glycogen is the long-term carbohydrate energy store.

Suggest one reason why hummingbirds build up a greater energy store in the form of
triglyceride, rather than a greater energy store of glycogen, in preparation for migration.

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

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

(c) In birds such as hummingbirds:

• blood is kept within vessels
• for each complete circuit of the body, blood passes through the heart twice.

State the term used to describe this type of circulatory system.

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

(d) The heart of birds has the same structure as the heart of mammals. Compared with the heart
of mammals, the heart of birds is larger in proportion to their body size.

Suggest why the heart of birds is larger in proportion to their body size.

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

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

(e) Complete Table 3.1 to show the names and functions of the main blood vessels associated
with the heart of mammals.

Table 3.1

function of blood vessel name of blood vessel

carries blood from the heart to the lungs
carries blood to the heart from the lungs
carries blood from the heart to the rest of the body
carries blood to the heart from the rest of the body
[3]

[Total: 12]

© UCLES 2022 9700/22/M/J/22 [Turn over

4 The enzyme carbonic anhydrase has been found in a wide range of organisms and acts as a
catalyst in many tissues.

Studies have shown that there are differences in the protein structure of the enzyme and differences
in the number and organisation of introns and exons of the gene coding for the enzyme.

All carbonic anhydrase enzymes catalyse the same reversible reaction, shown in Fig. 4.1.

carbonic anhydrase
CO2 + H 2O H2CO3 H+ + HCO3–
carbon water X hydrogen Y
dioxide ions

Fig. 4.1

(a) With reference to Fig. 4.1, name X and Y.

X ...............................................................................................................................................

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

(b) Carbonic anhydrase enzymes can have different primary structures.

Suggest how all carbonic anhydrase enzymes can catalyse the same reaction, even though
they have different primary structures.

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

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

Outline the similarities and differences between the introns and the exons of genes coding for
proteins such as carbonic anhydrase.

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

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

© UCLES 2022 9700/22/M/J/22

All mammals have the same type of carbonic anhydrase, known as α-carbonic anhydrase. Many
different forms, or isoforms, of α-carbonic anhydrase have been identified in mammals.

There are 15 isoforms of α-carbonic anhydrase (CA) in humans. Cells of different tissues have
one or more isoforms. Within cells the isoforms may be in different locations.

(d) Red blood cells contain two isoforms, CA1 and CA2.

Suggest the location of CA1 and CA2 in red blood cells and give a reason for your answer.

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

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

(e) Isoform CA6 forms part of human breast milk. Mammary gland cells package CA6 in Golgi
vesicles for release from the cells.

Name the transport mechanism associated with CA6 secretion.

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

(f) Human CA isoforms in some epithelial cells in the eye have a role in the formation of the clear
fluid of the eye known as aqueous humour. Overactivity of the enzyme may lead to a harmful
increase of pressure within the eye and cause a condition known as glaucoma.

Acetazolamide is a therapeutic drug that can be used in the treatment of glaucoma. It acts as
a reversible non-competitive inhibitor.

Describe the mechanism of action of acetazolamide as a reversible non-competitive inhibitor

of carbonic anhydrase.

��

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

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

[Total: 12]

© UCLES 2022 9700/22/M/J/22 [Turn over

5 Fig. 5.1 is a photomicrograph of a transverse section through part of the bronchus of the human
gas exchange system. The image is of a good resolution for a light microscope.

The bronchial epithelium is a single layer of cells lining the lumen of the bronchus.

lumen
D
luminal L
surface

bronchial
epithelium
A
elastic
fibres
B

magnification ×180

Fig. 5.1

(a) The luminal surface shown in Fig. 5.1 is not clearly defined and appears slightly blurred.

State why the luminal surface of the bronchial epithelium appears slightly blurred, even
though the resolution of the image is good.

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

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

(b) Some cells of the bronchial epithelium shown in Fig. 5.1 appear darker than others. For
example, cell D appears darker than cell L.

With reference to the bronchial epithelium shown in Fig. 5.1, explain why some cells, such as
cell D, appear darker and other cells, such as cell L, appear lighter.

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

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

© UCLES 2022 9700/22/M/J/22

(c) In Fig. 5.1 the tissue in box B is cartilage.

The tissue shown in box A is different from the tissue in box B.

Outline the differences in the structure and function of tissue A compared with tissue B.

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

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

[Total: 6]

© UCLES 2022 9700/22/M/J/22 [Turn over

6 The transport tissues of plants are phloem and xylem.

The role of xylem is the transport of water and mineral ions from the soil solution to the different
parts of the plant body.

The role of phloem is the translocation of assimilates and other substances from sources to sinks.

(a) The source of mineral ions for the plant is the soil solution. These mineral ions are transported
from the roots in the xylem. Mineral ions are also found in the phloem sap within phloem
sieve tubes.

Suggest why mineral ions are found within phloem sieve tubes and state how they are
transported within phloem sieve tubes.

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

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

(b) Phloem tissue consists of different cell types.

Complete the passage using the most appropriate terms to summarise some of the features
of phloem tissue.

The end walls of sieve tube elements are modified to allow efficient flow of phloem sap

by the formation of ....................................................................... . These structures also

prevent the cells from bursting under pressure. The cytoplasm of sieve tube elements is

very much reduced and is found at the ....................................................................... of the

cells. Most of the organelles in the cell are absent. Adjacent to sieve tube elements are

....................................................................... cells that carry out the metabolic processes of

the missing organelles, allowing the sieve tube elements to function. [3]

[Total: 6]

© UCLES 2022 9700/22/M/J/22

Cambridge International AS & A Level
* 6 0 4 3 8 5 5 2 5 2 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions October/November 2022

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Any blank pages are indicated.

DC (CE/SG) 301687/4
© UCLES 2022 [Turn over
2

1 The mammalian circulatory system is adapted for the long-distance transport of the respiratory
gases, oxygen and carbon dioxide.

The system is described as a closed double circulation.

(a) Name:

• the two different circulations of the double circulatory system of mammals

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

• the main vein returning deoxygenated blood to the heart.

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

(b) In a closed circulation, blood is kept within vessels at all times.

Name the type of blood vessel that connects capillaries and veins.

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

(c) Fig. 1.1 is a diagram of a section through the heart.

Fig. 1.1

On Fig. 1.1:

• add a label line and the letter L to show the artery that takes blood from the heart to
the lungs
• add a label line and the letter R to show the valve that closes when the right ventricle is
in systole. [2]

© UCLES 2022 9700/22/O/N/22

(d) The entry of carbon dioxide into red blood cells results in the production of hydrogencarbonate
ions. This involves the enzyme carbonic anhydrase.

Complete the passage summarising the production of hydrogencarbonate ions by:

• writing the correct biological term in the spaces provided

• writing the molecular formula for two of the terms in the spaces in brackets.

Carbonic anhydrase has an overall spherical shape and is known as a

............................................... protein. The enzyme acts within the cell so can be described

as an ............................................... enzyme. When blood passes into the capillary network

through actively respiring tissues, carbon dioxide (CO2) diffuses into red blood cells and

carbonic anhydrase catalyses a reaction where ............................................... (.................)

is combined with CO2 to form ............................................... (H2CO3), which rapidly forms

............................................... ions (.................) and hydrogencarbonate ions (HCO3–). [5]

[Total: 11]

© UCLES 2022 9700/22/O/N/22 [Turn over

2 Human cytomegalovirus (HCMV) is a common virus affecting humans. In people with a fully
functioning immune system, infection by HCMV usually causes no, or only mild, symptoms.

Fig. 2.1A is a diagram of a section through HCMV. In Fig. 2.1B, only the outer part of HCMV
is sectioned.

glycoprotein

double-stranded
DNA
S T

tegument
proteins

A B

Fig. 2.1

The viral DNA shown in Fig. 2.1 contains genes that code for proteins important in viral replication
and viral structure, including viral DNA polymerase and proteins known as tegument proteins.

Viruses can only replicate in host cells as they need to use processes and contents of the host
cell. Complete viral particles that are released from the host cell are known as virions.

(a) Structure S in Fig. 2.1A is a subunit of structure T in Fig. 2.1B.

Name the chemical compound used to make structure S and name structure T.

S ...............................................................................................................................................

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

(b) The actual diameter of the HCMV shown in Fig. 2.1 is 0.17 micrometres (µm).

Calculate the actual diameter of the virus in nanometres (nm).

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

© UCLES 2022 9700/22/O/N/22

(d) The virus in Fig. 2.1 is drawn as a spherical shape. Structure T is always the same shape.
However, electron micrographs show that HCMV virions are not all the same shape.

Suggest how HCMV virions can be of different shapes.

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

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

(e) With reference to Fig. 2.1A, state one similarity and one difference between the genetic
material of HCMV and the genetic material of a typical bacterial cell.

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

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

(f) HCMV is known to infect some types of human cell that carry out the mitotic cell cycle.

Studies have shown that in the presence of one tegument protein, UL69, the cell cycle stops
in the G1 stage.

Outline the effects the presence of UL69 will have on the normal activity of the mitotic
cell cycle.

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

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

© UCLES 2022 9700/22/O/N/22 [Turn over

(g) After a person has been infected with HCMV, the virus remains in a dormant state in the body
for life.

If the virus becomes active again (reactivates), the virus will only cause serious illness if the
person has a weak immune system at that time.

Explain why the response to reactivation of HCMV is more likely to cause serious illness in a
person who has a weak immune system.

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

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

[Total: 15]

© UCLES 2022 9700/22/O/N/22

3 Plasmodium falciparum is one species of Plasmodium that causes the life-threatening disease
malaria. With early diagnosis and the correct drug treatment, the pathogen can be eliminated from
the body, particularly if the disease is not severe.

(a) Name the type of pathogen that causes malaria.

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

(b) To help prevent the development and spread of drug resistance in Plasmodium, the World
Health Organization (WHO) recommends using a treatment known as artemisinin-based
combination therapy (ACT).

ACT involves two different types of drug:

• a fast-acting drug derived from a compound known as artemisinin, which causes a rapid
decrease in the number of P. falciparum
• one or more longer-acting, non-artemisinin, drugs that eliminate any remaining
pathogens.

(i) Suggest why using ACT with the two different types of drug is more effective in preventing
the development of drug resistance in Plasmodium than a treatment using only one type
of drug.

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

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

(ii) In some areas, partial artemisinin resistance has developed. This means ACT takes a
longer time for the pathogen to be eliminated from the body.

Explain why there is an increased risk of transmission of the pathogen to other people if
a person is receiving ACT and the pathogen has partial artemisinin resistance.

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

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

© UCLES 2022 9700/22/O/N/22 [Turn over

(c) ACT can act on the stage of the life cycle of P. falciparum that occurs within red blood cells.
The cells of P. falciparum in this stage are known as trophozoites.

Fig. 3.1 is a photomicrograph of a blood smear (thin layer of cells). Some of the red blood
cells contain trophozoites.

trophozoite

Fig. 3.1

PfK13 is a protein that has an important role in the development of the trophozoite stage of
P. falciparum. The gene kelch13 codes for PfK13.

Two different mutations of kelch13, known as F446I and C580Y, were investigated to see
if they were associated with partial artemisinin resistance. Details of these mutations are
summarised in Table 3.1.

Table 3.1

change in DNA change in protein PfK13

name of nucleotide nucleotide
mutation amino acid before amino acid after
present in present after
mutation mutation
kelch13 mutation
F446I thymine (T) adenine (A) phenylalanine (phe) isoleucine (ile)
C580Y guanine (G) adenine (A) cysteine (cys) tyrosine (tyr)

(i) Using gene kelch13 and mutation F446I as examples, explain the difference between a
gene and a gene mutation.

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

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

© UCLES 2022 9700/22/O/N/22

(ii) In the investigation, the survival rate of trophozoites within red blood cells was determined
for two different concentrations of an artemisinin-based drug known as DHA.

Two different strains, A and B, of P. falciparum were tested. Three different cultures of
each strain were involved:
• no mutation in kelch13 (control)
• kelch13 F446I mutation
• kelch13 C580Y mutation.

Table 3.2 shows the six different cultures tested and the trophozoite survival rate for
each culture.

Table 3.2

mean percentage survival rate of trophozoite

culture
culture details DHA concentration DHA concentration
number
20 nmol dm–3 700 nmol dm–3
1 strain A no mutation 3.15 0.00
2 strain A, F446I mutation 26.00 0.73
3 strain A, C580Y mutation 33.08 0.91
4 strain B no mutation 2.86 0.00
5 strain B, F446I mutation 13.50 0.53
6 strain B, C580Y mutation 17.50 0.63

State the main conclusions that can be drawn from the results shown in Table 3.2.

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

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

[Total: 11]

© UCLES 2022 9700/22/O/N/22 [Turn over

4 The airways of the gas exchange system are lined with epithelium. Gradual changes in the
structural features of this epithelium occur as the airways branch and become increasingly narrow.

(a) Table 4.1 shows the changes that occur in the number of goblet cells in the epithelium of the
different structures of the gas exchange system.

Table 4.1

gas exchange number of goblet cells

structure in epithelium
trachea many
bronchi many
larger bronchioles very few
smaller bronchioles none
alveoli none

Goblet cells produce mucus, which is important in maintaining the health of the airways.

The smallest bronchioles closest to the alveoli are known as respiratory bronchioles.

Suggest and explain why respiratory bronchioles do not have any goblet cells.

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

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

(b) Fig. 4.1 is a photomicrograph of a section through a bronchiole, which is surrounded

by alveoli.

tissue X

magnification ×40

Fig. 4.1
© UCLES 2022 9700/22/O/N/22
11

(i) There are structural differences between the epithelium of the bronchiole and the
epithelium of an alveolus.

Describe the differences between the epithelium of bronchioles and the epithelium of
alveoli, other than differences in the number of goblet cells.

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

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

(ii) Tissue X, shown in Fig. 4.1, is located in the wall of the bronchiole.

Name tissue X and outline the function of tissue X in the bronchiole.

tissue X = ........................................................

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

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

[Total: 8]

© UCLES 2022 9700/22/O/N/22 [Turn over

5 Fibroblasts are one of the cell types of connective tissue. The cells synthesise and secrete collagen,
which forms part of the supporting external cellular environment, known as the extracellular matrix.

(a) Fig. 5.1 shows the primary structure of a section of a polypeptide chain of collagen.

gly pro ala gly pro ser gly ala pro gly pro ile

Fig. 5.1

Explain how the primary structure shown in Fig. 5.1 indicates that the structure of the
polypeptide is suited to be a component of a collagen molecule.

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

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

(b) After final processing in the Golgi body, collagen is released to the outer surface of the cell by
exocytosis.

Complete the passage to describe the process of exocytosis.

After final processing in the Golgi body,

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

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

© UCLES 2022 9700/22/O/N/22

Cells also secrete inhibitors of collagenases. The activity of the enzymes and inhibitors is
regulated so that the development and maintenance of the extracellular matrix is controlled.

(i) State and explain what the outcome will be for the composition of the extracellular matrix
if collagenase inhibitor activity is needed.

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

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

(ii) Synthetic inhibitors have been trialled as potential treatment for diseases caused by a
lack of regulation of collagenase activity.

Research involves investigating the mechanism of action of an inhibitor.

State the effect that a non-competitive inhibitor will have on the maximum rate of
reaction, Vmax, and the Michaelis–Menten constant, Km, of collagenase.

Vmax ...................................................................................................................................

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

[Total: 10]

© UCLES 2022 9700/22/O/N/22 [Turn over

6 Xylem and phloem are the transport tissues of plants. Both tissues have more than one cell type.

The conducting cells of xylem contain xylem sap and those of phloem contain phloem sap.
The composition of xylem sap differs from the composition of phloem sap.

(a) The main component of xylem sap and phloem sap is water.

Explain why water is the main component of xylem sap and phloem sap.

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

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

(b) Three types of cell associated with the translocation of sucrose are:

• companion cell
• mesophyll cell
• phloem sieve tube element.

A, B and C are three events that occur at the source. Each event refers to ‘the cell’ but does
not name the type of cell concerned.

A Sucrose moves through plasmodesmata into the cell.

B Hydrogen ions are transported out of the cell.
C Sucrose moves into the cell through cotransporter proteins.

Complete Table 6.1 by matching the event with a correct cell type.

Each cell type may be identified once, more than once, or not at all.

Table 6.1

event cell type

[3]

[Total: 5]

© UCLES 2022 9700/22/O/N/22

BLANK PAGE

© UCLES 2022 9700/22/O/N/22

BLANK PAGE

© UCLES 2022 9700/22/O/N/22

Cambridge International AS & A Level
* 5 1 5 8 6 5 0 0 7 8 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions February/March 2021

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Any blank pages are indicated.

DC (MB/SG) 200195/2
© UCLES 2021 [Turn over
2

Answer all questions.

1 (a) Fig. 1.1 is an image of a transverse section through the trachea of the gas exchange system.

lumen of trachea

ciliated epithelium

perichondrium

X ........................................................

Y ........................................................

Fig. 1.1

Write the names of structures X and Y on Fig. 1.1 in the boxes provided. [2]

(b) The perichondrium contains collagen fibres, composed of collagen molecules.

Collagen is an example of one type of biological molecule.

State the name of the type of biological molecule of which collagen is an example.

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

• Write YES in the box provided if the structure contains smooth muscle.
• Write NO in the box provided if the structure does not contain smooth muscle.

Table 1.1

alveolus

bronchiole

bronchus

trachea
[1]

[Total: 4]

© UCLES 2021 9700/22/F/M/21

2 Starch molecules are the main storage molecules in many types of cereal grain, such as the grain
of the barley plant.

(a) When the seed inside a barley grain germinates, genes coding for digestive enzymes are
switched on. The enzymes that are synthesised catalyse the hydrolysis of storage molecules
such as proteins and starch.

(i) Explain what is meant by a gene.

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

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

(ii) The hydrolysis of proteins in the barley seed produces amino acids that can be used in
the synthesis of the proteins required for formation of the seedling (young plant).

Fig. 2.1 is an incomplete diagram of the molecular structure of the smallest amino acid,
glycine. Each molecule of glycine has two carbon atoms.

C C

Fig. 2.1

Complete Fig. 2.1 to show the molecular structure of glycine. [2]

(iii) Starch is a mixture of two different molecules.

Name these two molecules.

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

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

© UCLES 2021 9700/22/F/M/21 [Turn over

Two of the enzymes synthesised by the barley seed are α-amylase and maltase. These are
involved in the hydrolysis of the stored starch during seedling formation.

In the food industry, the starch extracted from barley seeds (barley starch) is used in the production
of sugar syrups. Fig. 2.2 summarises the reactions catalysed by α-amylase in the production of
maltose syrup and by maltase in the production of glucose syrup.

α-amylase
barley starch maltose

maltase
maltose glucose

Fig. 2.2

(b) Some of the substances shown in Fig. 2.2 are listed in Table 2.1.

Complete Table 2.1 to identify which of the terms polysaccharide, monosaccharide and
macromolecule apply to each of the substances listed.

Use a tick (3) if the term applies and a cross (7) if the term does not apply.

Put a tick (3) or a cross (7) in every box.

Table 2.1

substance polysaccharide monosaccharide macromolecule

glucose
maltase
maltose
starch
[3]

When producing sugar syrups, there are advantages in using enzymes extracted from
microorganisms.

For example, some enzymes extracted from microorganisms are heat stable. Heat-stable enzymes
are used to increase productivity because the reactions can be carried out at higher temperatures.

(c) Suggest one other advantage of using enzymes obtained from microorganisms, rather than
enzymes extracted from barley seeds, in the production of sugar syrups.

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

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

© UCLES 2021 9700/22/F/M/21

(d) Fig. 2.3 is a graph showing how the activity of a-amylase extracted from barley seeds
changes as the temperature increases from 10 °C to 66 °C.

100

60
percentage
enzyme 50
activity
40

0
0 10 20 30 40 50 60 70 80 90 100
temperature / °C

Fig. 2.3

(i) Explain the effect of temperature on the activity of α-amylase extracted from barley
seeds, as shown in Fig. 2.3.

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

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

(ii) Sketch on Fig. 2.3 the curve that would be obtained using α-amylase enzyme that is
heat stable. [2]

[Total: 14]

© UCLES 2021 9700/22/F/M/21 [Turn over

3 T-helper lymphocytes and Leydig cells are two types of mammalian cells. The main role of T-helper
lymphocytes and Leydig cells is to synthesise and secrete cell-signalling molecules.

• T-helper lymphocytes synthesise proteins known as cytokines.

• Leydig cells synthesise the steroid (lipid) hormone testosterone from cholesterol. Leydig cells
also synthesise cholesterol.

(a) State one way in which cytokines are involved in an immune response.

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

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

(b) Fig. 3.1 shows part of a mammalian cell.

Fig. 3.1

(i) State, with reasons, whether Fig. 3.1 shows part of a Leydig cell or part of a T-helper
lymphocyte.

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

..................................................................................................................................... [2]
© UCLES 2021 9700/22/F/M/21
7

(ii) Underline the correct name for the type of image shown in Fig. 3.1 and explain your
choice.

photomicrograph

scanning electron micrograph

transmission electron micrograph

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

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

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

(c) Testosterone molecules and cytokine molecules are transported in the circulatory system to
reach their target cells. Testosterone molecules are able to enter their target cells and bind to
receptors within the cytoplasm.

(i) Outline one way in which testosterone molecules could enter their target cells.

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

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

(ii) Cytokine molecules are not able to enter their target cells.

Suggest and explain why cytokine molecules are not able to cross the cell surface
membrane to enter their target cells.

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

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

[Total: 9]

© UCLES 2021 9700/22/F/M/21 [Turn over

4 (a) Using a light microscope at a magnification of ×400, it is possible to identify different types of
blood cell in prepared slides of mammalian blood.

Fig. 4.1 is a key to identify different types of blood cell in prepared slides of mammalian blood.

In Fig. 4.1, letters C, D, E and F represent four different types of blood cell.

key

1a nucleus present ................................................................................................ go to 2

1b nucleus absent ..................................................................................................... C

2a large rounded (spherical) nucleus ......................................................................... D

2b nucleus not rounded ......................................................................................... go to 3

3a nucleus is kidney shaped ..................................................................................... E

3b nucleus is lobed .................................................................................................... F

Fig. 4.1

(i) Identify the cell types C, D, E and F in Fig. 4.1.

C ........................................................................................................................................

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

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

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

(ii) Explain why blood taken from a person with an infectious disease may have a different
number of white blood cells compared with blood taken from a healthy person.

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

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

© UCLES 2021 9700/22/F/M/21

As part of a research project, a team of doctors and scientists carried out tests to investigate
the effect of altitude on the ability of blood to carry oxygen. They assessed the changes in the
oxygen-carrying ability of their own blood as they walked from 1530 m above sea level to 5700 m
above sea level, over a period of 14 days. 5700 m above sea level is an extremely high altitude.

Table 4.1 is a summary of some of their results.

Table 4.1

day 1 at 1530 m day 14 at 5700 m

percentage saturation of haemoglobin with oxygen in
95 82
blood leaving the lungs
volume of oxygen delivered to tissues by 100 cm3 of
19.3 19.2
blood / cm3

(b) Compare the results for day 1 with the results for day 14 in Table 4.1 and explain the results
shown for day 14.

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

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

Explain why sickle cell anaemia is an example of a disease.

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

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

[Total: 11]

© UCLES 2021 9700/22/F/M/21 [Turn over

5 Each meristem cell in a leaf bud is able to grow and divide by mitosis to produce two daughter
cells that are genetically identical to each other and to the original dividing cell.

(a) Fig. 5.1 lists the stages in the mitotic cell cycle of a meristem cell.

G1 phase

S phase

G2 phase

prophase

metaphase

anaphase

telophase

cytokinesis

daughter cell daughter cell

Fig. 5.1

(i) Outline and explain the events occurring during S phase, metaphase and anaphase of
the mitotic cell cycle that are important in the production of genetically identical daughter
cells.

S phase .............................................................................................................................

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

metaphase ........................................................................................................................

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

anaphase ..........................................................................................................................

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

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

© UCLES 2021 9700/22/F/M/21

(ii) Immediately after cytokinesis, daughter cells are not identical even though they are
genetically identical.

Suggest a reason why daughter cells are not identical immediately after cytokinesis.

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

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

(b) Some of the cells resulting from mitotic division in the young leaf form elongated cells that
develop into xylem vessel elements. The xylem vessel elements are joined end to end to
form xylem vessels.

(i) Suggest the structural changes that occur when elongated cells develop into xylem
vessel elements and explain how these changes help xylem vessels to perform their
function in transport.

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

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

(ii) Fig. 5.2 is a plan diagram of a transverse section through a dicotyledonous leaf.

Fig. 5.2

Add a label line and the letter X to Fig. 5.2 to identify the location of xylem tissue. [1]

[Total: 10]

© UCLES 2021 9700/22/F/M/21 [Turn over

6 In March 2019, a tropical cyclone in the south-west Indian Ocean caused widespread flooding in a
number of countries.

The flooding and the damage caused by the cyclone meant that many people were at serious risk
of cholera.

After the natural disaster occurred, many different areas reported outbreaks of cholera. Within a
short time the disease had spread widely and large numbers of people were affected.

(a) Cholera is caused by a bacterial pathogen.

Name the bacterial pathogen that causes cholera.

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

(b) Suggest and explain why the people affected by the cyclone were at serious risk of cholera.

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

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

© UCLES 2021 9700/22/F/M/21

(c) In addition to the standard treatment for cholera, antibiotics are recommended for people who
are moderately ill or seriously ill with the disease.

(i) Doxycycline is one of the main antibiotics used for the treatment of cholera.

Doxycycline enters the pathogen and binds to one of the subunits of the bacterial
ribosome. This prevents growth and reproduction of the bacterial cell.

Suggest and explain how binding of doxycycline to ribosomes stops growth of the
bacterial cell.

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

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

(ii) Penicillin, which used to be prescribed for the treatment of cholera, has a different
mechanism of action to doxycycline.

State which part of the bacterial cell is affected by the action of penicillin.

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

© UCLES 2021 9700/22/F/M/21 [Turn over

(d) Mozambique was one of the countries badly affected by the cyclone.

As part of the effort to prevent a greater number of cases of cholera from occurring, two
different approaches were taken.

• Approximately 900 000 doses of the oral cholera vaccine were sent to Mozambique and
a large-scale vaccination programme was organised.
• Medical centres were set up in Mozambique to treat people with cholera.

Suggest and explain how the two different approaches helped to prevent a greater number
of cases of cholera from occurring.

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

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

[Total: 12]

© UCLES 2021 9700/22/F/M/21

BLANK PAGE

© UCLES 2021 9700/22/F/M/21

BLANK PAGE

Cambridge Assessment International Education is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of
Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.

© UCLES 2021 9700/22/F/M/21

Cambridge International AS & A Level
* 8 8 6 6 5 5 0 3 9 5 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions May/June 2021

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Any blank pages are indicated.

DC (RW/FC) 200351/2
© UCLES 2021 [Turn over
2

Answer all questions.

1 (a) Fig. 1.1 is a photomicrograph of a region of eukaryotic tissue. Some of the cells are in stages
of mitosis.

E
F

Fig. 1.1

(i) Identify which stage of mitosis is shown in cell E and in cell F in Fig. 1.1.

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

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

(ii) Microtubules are present within the cells that are in stages of mitosis, but these are not
visible in Fig. 1.1.

State the function of microtubules in mitosis.

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

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

(iii) State, with a reason, whether Fig. 1.1 shows a region of animal or plant tissue.

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

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

© UCLES 2021 9700/22/M/J/21

(b) Semi‑conservative replication of DNA occurs during interphase, before mitosis begins.

Write the correct term in the spaces provided to complete each of statements A to D.

A The DNA double helix unwinds and is separated into two template strands when

....................................................................... bonds holding the two strands together

are broken.

B One of the template strands of DNA is copied in fragments. The enzyme

....................................................................... is required to join the fragments together

to form a continuous strand of DNA.

C Complementary DNA nucleotides are added to the template strands, catalysed by the

enzyme ....................................................................... .

D ....................................................................... are regions of repeating nucleotide

sequences at the ends of chromosomes that allow the continued replication of DNA,

without the loss of genes.

[4]

[Total: 8]

© UCLES 2021 9700/22/M/J/21 [Turn over

2 Sugars are transported within phloem sieve tubes from a source, such as a mature leaf, to a
young leaf, which acts as a sink. The young leaf also needs water and dissolved mineral ions,
which arrive at the leaf within xylem vessels.

(a) As the young leaf matures, the quantity of sugar taken up by the leaf decreases to zero, but
the need for water increases.

Suggest and explain why the quantity of sugar taken up by the developing leaf decreases to
zero over time, but the need for water increases.

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

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

(b) The features listed in Table 2.1 are present in one or more of the three cell types:

• companion cell
• phloem sieve tube element
• xylem vessel element.

Complete Table 2.1 using a tick (3) if the feature is present and a cross (7) if the feature is
absent.

Table 2.1

companion phloem sieve xylem vessel

feature
cell tube element element

cytoplasm

cell surface membrane

lignified cell wall

nucleus

[4]

[Total: 7]

© UCLES 2021 9700/22/M/J/21

3 In mammals, some cell signalling molecules are steroid (lipid) hormones. These hormones are
transported in the bloodstream to reach capillary networks.

At a capillary network, hormones pass out of the blood into tissue fluid.

(a) Fig. 3.1 is a diagram of a capillary network.

X body cells
tissue
fluid

blood blood
from to
artery vein

Fig. 3.1

(i) Describe the differences between the blood arriving at the arterial end of the capillary
network and the tissue fluid surrounding the body cells.

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

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

(ii) Not all the tissue fluid passes back into the blood capillaries to enter the bloodstream.
Some of the tissue fluid drains into blind‑ended vessels, such as vessel X shown in
Fig. 3.1.

Name the fluid that is formed in vessel X.

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

© UCLES 2021 9700/22/M/J/21 [Turn over

Hormone S is a steroid hormone involved in cell signalling.

Fig. 3.2 shows the sequence of events that occurs when hormone S enters a target cell.

hormone-receptor
complex

R
DNA

C
G
nuclear
cell surface envelope
membrane
KEY:
not to scale
hormone S
cell surface membrane receptors
cytoplasmic receptors
nuclear receptor
messenger RNA molecule
polypeptide

Fig. 3.2

(b) Explain why hormone S, shown in Fig. 3.2, does not need to pass through a transport protein
to enter the cytoplasm of the target cell.

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

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

(c) The target cell can respond to other cell signalling molecules in addition to hormone S. The
cell has receptors in the cell surface membrane, in the cytoplasm and in the nucleus.

Explain why hormone S binds only with receptor R in the cytoplasm and not with the other
receptors shown in Fig. 3.2.

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

............................................................................................................................................. [1]
© UCLES 2021 9700/22/M/J/21
7

(d) The hormone‑receptor complex shown in Fig. 3.2 enters the nucleus and binds to DNA. This
switches on a gene coding for a polypeptide that is synthesised in the cytoplasm.

(i) Name the structure through which the hormone‑receptor complex enters the nucleus.

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

(ii) Name the processes occurring at B and C.

B ........................................................................................................................................

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

(iii) Name structure G.

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

(e) Cell signalling by hormone S results in the production of a functioning globular protein
molecule composed of three identical polypeptide chains.

After the synthesis of these polypeptides, changes need to occur to form the functioning
globular protein molecule.

Outline the changes that need to occur to form the functioning globular protein molecule.

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

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

[Total: 15]

© UCLES 2021 9700/22/M/J/21 [Turn over

4 A person who is exposed to tobacco smoke is at greater risk of lung cancer and chronic obstructive
pulmonary disease (COPD).

Many people with COPD have both chronic bronchitis and emphysema. These diseases cause
changes in the gas exchange system. For example, changes occur in the total lung surface area
to volume ratio (SA:V).

(a) Tar in tobacco smoke has a number of effects on the cells lining the gas exchange system.

State the main effects of tar on the cells lining the gas exchange system that are related to
lung cancer and to chronic bronchitis.

lung cancer ...............................................................................................................................

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

chronic bronchitis ......................................................................................................................

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

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

© UCLES 2021 9700/22/M/J/21

(b) A student investigated the effect of SA:V on diffusion.

Agar was prepared with Universal Indicator solution and sodium hydroxide solution. The agar
was coloured blue.

Three cubes, A, B, and C, were cut from a solid block of blue agar. Each cube was a different
size.

Universal Indicator solution changes to a red colour in the presence of acid.

The student prepared Table 4.1 to show the sizes and SA:V of each cube.

Table 4.1

cube length of each total surface volume / SA:V

side / cm area / cm2
.....................

A 1 6 1 6:1

B 2 24 8 3:1

C 3 2:1

Complete Table 4.1 by:

• writing the correct units for volume
• calculating the total surface area, and volume, of cube C.
[2]

(c) Cubes A, B and C were placed in a small beaker. At time 0 seconds, dilute hydrochloric acid
was added to the beaker to cover the cubes.

The student timed how long it took for each cube to change colour completely.

Complete Fig. 4.1 to show the results that were obtained.

shortest time to longest time to

change colour change colour
completely completely

cube ......................... cube ......................... cube .........................

[1]

Fig. 4.1

© UCLES 2021 9700/22/M/J/21 [Turn over

(d) Some people with emphysema may be offered lung volume reduction surgery (LVRS), in
which diseased lung tissue is surgically removed.

One expected outcome of the surgery is an improvement in total lung surface area to volume
ratio (total lung SA:V).

Suggest why there is an improvement in total lung SA:V after the surgery has been carried
out.

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

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

(e) In humans, blood that becomes oxygenated in the lungs reaches body tissues without coming
into contact with blood that is deoxygenated.

Explain how the blood that becomes oxygenated in the lungs is kept separate from blood that
is deoxygenated.

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

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

[Total: 10]

© UCLES 2021 9700/22/M/J/21

5 Fig. 5.1 is a transmission electron micrograph showing parts of two plant cells. The function of the
middle lamella is cell‑to‑cell adhesion. The middle lamella is composed of a polysaccharide known
as pectin.

Pectin interacts with the polysaccharides cellulose and hemicellulose in the cell walls of the plant
cells so that the cell walls are held close together, as shown in Fig. 5.1.

Golgi body

middle lamella

Fig. 5.1

(a) Cell structure X in Fig. 5.1 is a cytoplasmic channel with strands of cytoplasm passing through
the cell walls of the two cells.

Name cell structure X and state one function of this cell structure.

name .........................................................................................................................................

function .....................................................................................................................................

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

(b) Researchers have discovered that pectin is synthesised within the Golgi body. Golgi vesicles
containing pectin are moved to the cell surface membrane for release.

(i) Suggest why researchers would not have investigated ribosomes as being the possible
location for the synthesis of pectin.

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

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

(ii) Name the mechanism that is used to transport pectin out of the cell.

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

© UCLES 2021 9700/22/M/J/21 [Turn over

Juices that are extracted commercially from fruits can be made less cloudy by the breakdown of
the cell wall using the enzymes cellulase, pectinase and xylanase:

• cellulase hydrolyses cellulose

• pectinase hydrolyses pectin
• xylanase hydrolyses hemicellulose.

(c) Fig. 5.2 is a graph showing the effect of cellulose concentration on the activity of cellulase,
which is used in making fruit juice less cloudy.

300

240

rate of reaction 180

/ mg product
cm–3 min–1 120

0
0 20 40 60 80 100
cellulose concentration / mg cm–3

Fig. 5.2

Describe and explain the curve shown in Fig. 5.2.

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

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

© UCLES 2021 9700/22/M/J/21

(d) Ultrasound is one possible method that can be used to destroy microorganisms that
contaminate fruit juices. Ultrasound is the term given to sound waves that are out of the range
of human hearing.

An investigation was carried out into the effect of ultrasound on the activity of cellulase,
pectinase and xylanase used in fruit juice manufacture.

For each enzyme, the effect of ultrasound was compared with no ultrasound on the:
• maximum rate of reaction (Vmax)
• Michaelis‑Menten constant (Km)
• catalytic efficiency (Vmax / Km)

Table 5.1 summarises the results. A higher Vmax / Km indicates a higher catalytic efficiency.

Table 5.1

comparison comparison Vmax / Km

enzyme method
of Vmax of Km / min–1
ultrasound higher higher 34
cellulase
no ultrasound lower lower 29
ultrasound same lower 945
pectinase
no ultrasound same higher 759
ultrasound higher same 146
xylanase
no ultrasound lower same 125

(i) In terms of changes in the interaction between enzyme and substrate when ultrasound
is used, suggest explanations for the lower Km for pectinase and the higher Vmax for
xylanase, as shown in Table 5.1.

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

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

(ii) Explain whether the data shown in Table 5.1 supports the recommendation that
ultrasound can be used in the manufacture of fruit juices.

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

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

[Total: 11]
© UCLES 2021 9700/22/M/J/21 [Turn over
14

6 The diseases myasthenia gravis (MG) and HIV/AIDS both involve disorders of the immune system.

(a) The cause of MG involves a response by B‑lymphocytes.

Explain why MG is called a disorder of the immune system.

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

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

(b) Studies have indicated that T‑lymphocytes are involved in stimulating the B‑lymphocyte
response that causes MG.

Research has been carried out on a vaccine that will provide a person with active immunity
against these T‑lymphocytes and B‑lymphocytes.

Suggest and explain how this vaccine will provide a person with active immunity against the
T‑lymphocytes and B‑lymphocytes responsible for causing MG.

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

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

(c) Many people who are living with HIV (infected with HIV) develop tuberculosis (TB). If a person
does not have any symptoms of TB, one preventive measure is to prescribe antibiotics. This
reduces the overall number of cases of TB and deaths from TB.

State the disadvantage of prescribing antibiotics as a preventive measure against TB.

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

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

© UCLES 2021 9700/22/M/J/21

(d) Fig. 6.1 is a summary of some of the statistics published by UNAIDS (Joint United Nations
Programme on HIV and AIDS) about HIV and HIV/AIDS for the year 2017.

The figures shown in Fig. 6.1 for 2017 are estimated.

globally, 36.9 million

people were living
with HIV

1.8 million people

became infected with
HIV
35.1 million adults and
1.8 million children
(under 15 years)
21.7 million were
provided with ART
(antiretroviral therapy)
940 000 people died
from HIV/AIDS

47% of the people provided with

ART, while still living with HIV, do
not have detectable levels of the
virus in their blood

Fig. 6.1

One other statistic published by UNAIDS indicated that, in 2017, only 75% of the estimated
36.9 million people living with HIV knew that they had been infected with the virus.

With reference to the information in Fig. 6.1, discuss the importance of this statistic.

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

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

[Total: 9]

© UCLES 2021 9700/22/M/J/21

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© UCLES 2021 9700/22/M/J/21

Cambridge International AS & A Level
* 1 6 2 7 2 5 3 4 4 9 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions October/November 2021

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Any blank pages are indicated.

DC (LK/SW) 203849/2
© UCLES 2021 [Turn over
2

Answer all questions.

1 There are two types of cell, prokaryotic and eukaryotic. Bacterial cells are prokaryotic and plant
cells are eukaryotic.

(a) There are differences in the structural features that are common to bacterial cells and plant
cells. For example, the cell surface membrane in a plant cell contains cholesterol, but in
a bacterial cell the membrane contains molecules known as hopanoids. Cholesterol and
hopanoids have the same function.

Some of the main structural features common to both types of cell are shown in Table 1.1.

Complete Table 1.1 by giving one difference between a bacterial cell and a plant cell for each
structural feature listed.

The difference between the cell surface membranes of the two types of cell has been
completed for you.

Table 1.1

feature common
to bacterial and bacterial cell plant cell
plant cells

cell surface
contains hopanoids contains cholesterol
membrane

ribosome

DNA

cell wall

[3]

(b) One role of the cell surface membrane of bacterial cells and plant cells is the transport of
substances into and out of cells.

Explain how membrane carrier proteins and membrane channel proteins are involved in the
transport of substances into and out of cells.

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

............................................................................................................................................. [3]
© UCLES 2021 9700/22/O/N/21
3

(c) Fig. 1.1 is a photomicrograph showing chloroplasts in plant leaf cells.

chloroplasts

Fig. 1.1

Explain why the chloroplasts are seen only around the periphery (edge) of each plant cell.

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

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

(d) Fig. 1.2 shows plant cells in a root tip where cell division by mitosis is taking place.

Fig. 1.2

Identify two cells in Fig. 1.2 that are in different stages of mitosis.

Draw a label line to each cell and add the name of the stage of mitosis that is shown by the
cell. [2]

[Total: 9]

© UCLES 2021 9700/22/O/N/21 [Turn over

2 The high blood pressure at the arterial end of a capillary network results in some components of
blood leaving the capillaries and forming tissue fluid. At the venous end, the presence of plasma
proteins allows movement of water by osmosis back into the capillaries.

Fig. 2.1 is a diagram showing a capillary network. The lymph vessels and the blood vessels at the
arterial and venous ends of the network are also shown.

capillaries

tissue
fluid

body
cells lymph
vessel

Fig. 2.1

(a) Red blood cells and plasma proteins, such as albumin, remain in the capillaries and are not
found in tissue fluid.

Explain why red blood cells and albumin do not leave the capillary.

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

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

(b) Name the chemical reagent or reagents used to test for proteins in a sample of blood plasma
and state the colour change that will be seen if protein is present.

reagent or reagents ..................................................................................................................

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

colour change ...........................................................................................................................

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

© UCLES 2021 9700/22/O/N/21

(c) When a person moves from sea level and stays at high altitude for a few months, there is an
increase in the number of red blood cells per mm3 of blood.

Explain why this increase occurs.

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

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

(d) A low blood albumin concentration can lead to a condition known as oedema.

Oedema is a swelling of tissues caused by the accumulation of tissue fluid surrounding the
body cells in the capillary network.

Suggest and explain how a low blood albumin concentration can lead to oedema.

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

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

(e) Albumin transports some cell signalling molecules from the cells where they are synthesised
to their target cells. The cell signalling molecules bind to specific cell surface membrane
proteins on the target cells.

Name the type of membrane protein to which the cell signalling molecules bind.

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

[Total: 11]

© UCLES 2021 9700/22/O/N/21 [Turn over

3 Baculovirus is a virus that kills some of the insect pests of major crops. When the virus is released
to the outside of the insect body, it is contained within stable, protective structures known as
polyhedrons.

The main component of the polyhedron is a protein molecule, polyhedrin.

Polyhedrons can be sprayed onto plants as a bioinsecticide. They are ingested by feeding insect
larvae and once inside the insect gut they break down to release the virus.

(a) Explain why the term infectious disease can be used to describe the effect of baculovirus on
insects.

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

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

(b) Suggest and explain the conditions present in the insect gut that can cause the breakdown of
polyhedrons.

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

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

(c) A polyhedrin molecule is composed of three identical polypeptides. Each polypeptide is 245
amino acids long. The first 10 amino acids of the polypeptide are shown in Fig. 3.1.

1 2 3 4 5 6 7 8 9 10
met — pro — asp — tyr — ser — tyr — arg — pro — thr — ile —

Fig. 3.1

Fig. 3.2 A is a ribbon diagram of a single polypeptide. Fig. 3.2 B shows a polyhedrin molecule
composed of 3 polypeptides.

The two diagrams are not to the same scale.

A B

Fig. 3.2
© UCLES 2021 9700/22/O/N/21
7

With reference to Fig. 3.1 and Fig. 3.2, describe the structure of a polyhedrin molecule.

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

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

(d) The sequence of DNA nucleotides for the gene in baculovirus that codes for the polyhedrin
polypeptide has been determined.

Explain why the amino acid sequence of the polypeptide cannot be used to deduce this
sequence of nucleotides in the gene that codes for the polyhedrin polypeptide.

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

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

[Total: 11]

© UCLES 2021 9700/22/O/N/21 [Turn over

4 Barlinka is a variety of the common grapevine, Vitis vinifera. Barlinka grapes are used for making
wine and are sold as fruit. There are economic and ecological benefits from using less water to
irrigate grapevine plants, while still producing a high crop yield.

The rate of flow of sap within xylem vessels from roots to leaves can be used as an estimate of the
rate of transpiration. This also indicates water uptake.

(a) The hydrogen bonding of water molecules is important in the transport of sap within xylem
vessels.

State the terms used to describe:

• water molecules sticking together within the xylem vessel

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

• water molecules sticking to the cellulose molecules in the lining of the xylem vessel

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

(b) An experiment was carried out to investigate the effect of leaf area on the rate of flow of the
xylem sap during fruit development.

The flow rate was measured over a three-day period in three Barlinka grapevine plants with
different total leaf area. The plants were growing in the same conditions.

The results are shown in Fig. 4.1.

Key
leaf area grapevine 1 / 13.7 m2
leaf area grapevine 2 / 9.6 m2
leaf area grapevine 3 / 3.2 m2
400

300

flow rate of
xylem sap /
cm3 per plant
200
per hour

100

0
1 2 3
day

Fig. 4.1
© UCLES 2021 9700/22/O/N/21
9

(i) The general pattern of results in Fig. 4.1 is the same for the three Barlinka grapevines.

Explain why the general pattern of results is the same.

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

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

(ii) With reference to Fig. 4.1, explain the differences in the results between the three
grapevines, 1, 2 and 3.

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

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

(iii) Suggest an explanation for the decrease in flow rate of xylem sap shown at time P in
Fig. 4.1.

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

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

(iv) Outline how you would determine the surface area of one side of a leaf.

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

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

[Total: 9]

© UCLES 2021 9700/22/O/N/21 [Turn over

5 The causative organism of measles is Morbillivirus. Young children who have not been vaccinated
for measles are at highest risk of becoming ill and of developing complications associated with the
disease.

(a) The genetic material of Morbillivirus is a strand of RNA.

Statements A, B and C relate to the structure of RNA.

State the correct term or terms to match each of statements A to C.

A The names of the two purines and two pyrimidines in RNA.

purines .....................................................................

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

pyrimidines .....................................................................

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

B The type of covalent bond between RNA nucleotides.

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

C The pentose sugar of the RNA nucleotide.

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

(b) Describe how measles is transmitted.

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

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

© UCLES 2021 9700/22/O/N/21

(c) Young children with measles may develop difficulties with breathing. This is made worse if the
child is continually exposed to tobacco smoke. Tobacco smoke contains harmful compounds,
such as carbon monoxide.

(i) Inhaled tobacco smoke passes through the larynx (voice box) and other structures in the
gas exchange system to reach the alveoli.

Complete Fig. 5.1 to list, in the correct sequence, the main structures of the gas exchange
system through which the tobacco smoke passes to reach the alveoli.

larynx

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

alveoli

Fig. 5.1
[1]

(ii) State the short-term effects of carbon monoxide on the cardiovascular system.

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

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

© UCLES 2021 9700/22/O/N/21 [Turn over

(d) Smallpox is a disease that has been eradicated with the help of a global vaccination
programme. Measles has not been eradicated, even though there is a global vaccination
programme.

Fig. 5.2 is a graph showing the estimates of number of deaths from measles globally, between
2000 and 2017, for people who have not been vaccinated.

2.0

1.5

number of
deaths from
measles in 1.0
millions

0.5

0.0
00

17
20
20

20
year

Fig. 5.2

(i) State the trend shown in Fig. 5.2 between 2000 and 2017.

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

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

© UCLES 2021 9700/22/O/N/21

(ii) Suggest reasons for the trend shown in Fig. 5.2.

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

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

(e) A child with leukaemia is at high risk of developing measles even though the child has a high
white blood cell count and has been vaccinated against the disease.

Explain why this child is at high risk of developing measles.

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

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

[Total: 16]

© UCLES 2021 9700/22/O/N/21 [Turn over

6 Amylase is an enzyme that catalyses the hydrolysis of starch into reducing sugars.

A student carried out an experiment to investigate the hydrolysis of starch using immobilised
amylase. Fig. 6.1 is a diagram of the apparatus that was used in the investigation.

starch
solution

tap

immobilised
amylase
in alginate beads

tap

beaker for
collecting
product

Fig. 6.1

The alginate beads were all the same size.

Both taps were opened to allow the starch solution to flow down the column and for the product to
be collected.

The product was tested for the presence of reducing sugar and starch.

© UCLES 2021 9700/22/O/N/21

(a) The results of the investigation showed that the product collected in the beaker contained
reducing sugar and starch.

With reference to Fig. 6.1, describe a method that would allow the student to use the
immobilised amylase to collect a product that contains only reducing sugar.

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

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

(b) One standardised variable in the investigation is the size of the alginate beads.

Suggest one reason why using larger or smaller alginate beads in the column would affect
the results obtained.

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

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

[Total: 4]

© UCLES 2021 9700/22/O/N/21

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© UCLES 2021 9700/22/O/N/21

Cambridge International AS & A Level
*0464412317*

CHEMISTRY9701/22
Paper 2 AS Level Structured Questions February/March 2020

1 hour 15 minutes

You must answer on the question paper.

You will need: Data booklet

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.
●● You may use a calculator.
●● You should show all your working, use appropriate units and use an appropriate number of significant
figures.

INFORMATION
●● The total mark for this paper is 60.
●● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Blank pages are indicated.

IB20 03_9701_22/4RP
© UCLES 2020 [Turn over
2

Answer all the questions in the spaces provided.

1 Group 2 metals form alkaline solutions in water.

(a) (i) Write the equation for the reaction of calcium oxide with water.

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

(ii) Identify the ion that causes an aqueous solution to be alkaline.

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

(b) The table shows the melting points of some Group 2 metal oxides.

compound melting point / °C

MgO 2825
CaO 2613
SrO 2531
BaO 1923

Explain the trend in the melting points of the oxides down Group 2.

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

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

(c) Oxygen reacts readily with some metals, but each Group 2 metal requires strong heating to
start the reaction with oxygen.

Suggest why strong heating is required to start these reactions.

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

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

(d) Beryllium oxide reacts with hydrochloric acid to form molecules of BeCl 2.

Deduce the bond angle in BeCl 2.

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

© UCLES 2020 9701/22/F/M/20

(e) Unlike the other oxides of Group 2 metals, beryllium oxide is amphoteric.

(i) Give the meaning of the term amphoteric.

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

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

(ii) Beryllium oxide and aluminium oxide have similar chemical properties.

The Be(OH)42– anion is a product of the reaction between beryllium oxide and excess
concentrated OH–(aq).

Construct an equation for this reaction.

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

(f) Magnesium oxide reacts reversibly with chlorine according to the following equation.

2MgO(s) + 2Cl 2(g) 2MgCl 2(s) + O2(g)

Under certain conditions, a dynamic equilibrium is established.

(i) State two features of a reaction that is in dynamic equilibrium.

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

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

(ii) The equilibrium constant, Kp, is given by the following expression.

pO
Kp = 2
2

pCl 2

At 1.00 × 105 Pa and 500 K, 70% of the initial amount of Cl 2(g) has reacted.

Calculate Kp and state its units.

Kp = ..............................

units = ..............................
[3]

© UCLES 2020 9701/22/F/M/20 [Turn over

(g) Magnesium peroxide, MgO2, is made in the following reaction.

MgO(s) + H2O2(l) MgO2(s) + H2O(l) ∆H = –96 kJ mol–1

enthalpy change of
compound
formation, ∆Hf / kJ mol–1
MgO(s) –602
H2O2(l) –188
H2O(l) –286

(i) The peroxide ion is O22–.

Deduce the average oxidation number of oxygen in the peroxide ion.

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

(ii) Define the term enthalpy change of formation.

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

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

(iii) Use the data given to calculate the enthalpy change of formation of MgO2(s).

∆Hf MgO2(s) = .............................. kJ mol–1 [2]

© UCLES 2020 9701/22/F/M/20

(iv) Magnesium peroxide decomposes slowly to form magnesium oxide and oxygen.
1
MgO2(s) MgO(s) + 2 O2(g)

Use your answer to (g)(iii) and the data in the table to calculate the enthalpy change of
this reaction.

If you were unable to obtain an answer to (g)(iii), use the value ∆Hf = –550 kJ mol–1. This

is not the correct answer.

enthalpy change of reaction = .............................. kJ mol–1 [1]

[Total: 19]

© UCLES 2020 9701/22/F/M/20 [Turn over

2 The Group 17 elements, chlorine, bromine and iodine, are non-metals that show trends in their
physical and chemical properties.

(a) Describe the trend in the colour of the Group 17 elements down the group.

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

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

(b) The Group 17 elements can oxidise many metals to form halides.

(i) Describe the relative reactivity of the elements in Group 17 as oxidising agents.

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

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

(ii) Chlorine reacts with hot tin metal to form tin(IV) chloride, SnCl 4.

SnCl 4 is a colourless liquid at room temperature that reacts vigorously with water to form
an acidic solution.

Suggest the type of structure and bonding shown by SnCl 4. Explain your answer.

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

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

(c) The Group 17 elements form soluble halides with sodium.

(i) Describe what is seen when dilute AgNO3(aq) is added to NaBr(aq) followed by aqueous
ammonia.

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

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

© UCLES 2020 9701/22/F/M/20

(ii) NaCl reacts with concentrated H2SO4 to form HCl and NaHSO4.

Explain the difference between the reactions of concentrated H2SO4 with NaCl and with
NaI. Your answer should refer to the role of the sulfuric acid in each reaction.

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

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

(d) The hydrogen halides are useful reagents in organic and inorganic reactions.

(i) Describe and explain the trend in the boiling points of the hydrogen halides, HCl, HBr and
HI.

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

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

(ii) Describe and explain the trend in the thermal stabilities of the hydrogen halides, HCl, HBr
and HI.

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

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

© UCLES 2020 9701/22/F/M/20 [Turn over

(e) Lucas’s reagent is a mixture of HCl and ZnCl 2. Primary, secondary and tertiary alcohols can
be distinguished by their reaction with Lucas’s reagent.

Alcohols react with the HCl in Lucas’s reagent to form halogenoalkanes.

ZnCl 2 acts as a homogeneous catalyst for these reactions.

(i) Explain the meaning of the term homogeneous.

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

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

(ii) Pentan-3-ol, C2H5CH(OH)C2H5, reacts slowly with HCl to form a secondary halogenoalkane.

Complete the equation for this reaction using structural formulae.

C2H5CH(OH)C2H5 + �� [1]

(iii) The fastest reaction shown by Lucas’s reagent is with a tertiary alcohol.

Draw the structure of the tertiary alcohol that is an isomer of pentan-3-ol.

[1]

(iv) Tertiary alcohols tend to react with Lucas’s reagent using the same mechanism as in their
reaction with HCl.

Suggest the type of reaction shown by tertiary alcohols with Lucas’s reagent.

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

[Total: 17]

© UCLES 2020 9701/22/F/M/20

3 Glycerol, CH2(OH)CH(OH)CH2OH, is widely used in the food industry and in pharmaceuticals.

(a) A series of reactions starting from glycerol is shown.

P Q
CH2OH HOOC COOH
NaCN and HCN
H C OH C O NC C OH
reaction 1 reaction 2
CH2OH HOOC COOH

(i) Suggest the reagent(s) and conditions for reaction 1.

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

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

(ii) Name the reaction mechanism for reaction 2.

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

(iii) Give the observation you would make when 2,4-dinitrophenylhydrazine is added to P.

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

(iv)
Q does not show optical isomerism.

Explain why.

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

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

(v) When Q is heated with excess aqueous ethanoic acid in the presence of a catalytic amount
of sulfuric acid, two reactions take place to form compound R.

R
COOH

HOOC C OCOCH3

COOH

Identify the two types of reaction that occur.

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

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

© UCLES 2020 9701/22/F/M/20 [Turn over

(b) Glycerol can be used as a starting material in the manufacture of nitroglycerine, C3H5N3O9.

Nitroglycerine decomposes rapidly on heating to form a mixture of gases.

4C3H5N3O9(l) 12CO2(g) + 10H2O(g) + 6N2(g) + O2(g)

A sample of nitroglycerine decomposes, releasing 1.06 dm3 of O2(g) at 850 K and 1.00 × 105 Pa.

(i) Calculate the mass of nitroglycerine that decomposes.

mass of nitroglycerine = .............................. g [3]

(ii) Calculate the total volume of gas released by this decomposition at 850 K and 1.00 × 105 Pa.

total volume of gas = .............................. dm3 [1]

© UCLES 2020 9701/22/F/M/20

4-pentenoic acid is an example of an unsaturated carboxylic acid.

4-pentenoic acid
(CH2)2COOH
H
H
H

(i) Give the molecular formula of 4-pentenoic acid.

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

(ii) Draw the repeat unit of the addition polymer that can be formed from 4-pentenoic acid.

[1]

(iii) Unsaturated acids are often brominated before being added to soft drinks.

Complete the mechanism for the addition of Br2 to 4-pentenoic acid.

●● Include the structures of the intermediate and the product of the reaction.
●● Include all charges, partial charges, lone pairs and curly arrows.

In the mechanism, R has been used to represent (CH2)2COOH.

R
H
H
H

Br
[4]

© UCLES 2020 9701/22/F/M/20 [Turn over

(d) A reaction of another unsaturated carboxylic acid, T, is shown.

T U
C6H13 C6H13
HOOC HOOC
Br Br

(i)
T is one of a pair of geometrical (cis-trans) isomers.

Draw the other geometrical isomer of T and explain why the molecules exhibit this form of
isomerism.

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

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

(ii) Identify the reagent used to convert T to U.

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

© UCLES 2020 9701/22/F/M/20

(iii) The C–Br bond has an absorption between 500 cm–1 and 600 cm–1 in an infrared spectrum.

The infrared spectra for both T and U have absorptions between 2850 cm–1 and 2950 cm–1.
These correspond to C–H bonds.

Identify:
●● two other absorptions that would be seen in the infrared spectra of both T and U
●● one other absorption that would only be seen in the infrared spectrum of T.

For each absorption, give the range of the absorption and the bonds that correspond to
these absorptions.

absorption 1 present in both spectra ...................................................................................

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

absorption 2 present in both spectra ...................................................................................

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

absorption only present in spectrum of T ............................................................................

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

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

[Total: 24]

© UCLES 2020 9701/22/F/M/20 [Turn over

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© UCLES 2020 9701/22/F/M/20

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© UCLES 2020 9701/22/F/M/20

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© UCLES 2020 9701/22/F/M/20

Cambridge International AS & A Level
* 6 4 9 9 4 1 3 9 8 6 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions May/June 2020

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Blank pages are indicated.

DC (LB/SW) 185259/2
© UCLES 2020 [Turn over
2

Answer all questions.

1 Picornaviruses are small viruses that are 30 nm in diameter. Picornaviruses are able to enter the
cells of mammals and birds and can replicate within these cells.

Fig. 1.1 shows the entry of a picornavirus into its host cell.

picornavirus

host cell
surface
membrane
not to scale

Fig. 1.1

(a) State the key features of a virus, such as picornavirus.

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

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

© UCLES 2020 9700/22/M/J/20

(b) State, with reasons, whether a picornavirus can be seen using the light microscope.

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

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

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

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

[Total: 8]

© UCLES 2020 9700/22/M/J/20 [Turn over

2 In a healthy mammalian heart, contraction of the four chambers is coordinated by the action of the
sinoatrial node (SAN) and atrioventricular node (AVN).

(a) After the atria fill with blood, atrial systole (contraction) occurs.

State the events that occur to initiate and cause atrial systole.

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

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

(b) State and explain how the structure of the heart allows the atria to contract before the
ventricles.

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

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

© UCLES 2020 9700/22/M/J/20

(c) Fig. 2.1 shows blood pressure changes that occur in the left ventricle, left atrium and aorta
during one cardiac cycle.

E, F, G and H are the points at which a valve opens or closes as a result of blood pressure
changes.

12 G
F
aorta
10
blood 8
pressure
left ventricle
/ kPa 6
left atrium
4

2 H
E
0

–2
0 0.75
time / s

Fig. 2.1

(i) For each of the points E, F, G and H on Fig. 2.1, name the valve concerned and state
whether the valve opens or closes.

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

F .............................................................................

G .............................................................................

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

(ii) Explain how Fig. 2.1 provides evidence that the wall of the left atrium has a different
thickness to the wall of the left ventricle.

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

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

[Total: 9]

© UCLES 2020 9700/22/M/J/20 [Turn over

3 The Bacillus Calmette-Guérin (BCG) vaccine is the only vaccine used to provide protection
against the infectious bacterial disease tuberculosis (TB). Most countries of the world have a BCG
vaccination programme.

(a) TB is most commonly transmitted from person to person by aerosol infection. The causative
organism is present in airborne droplets.

Name the species of causative organism of TB commonly passed from person to person by
aerosol infection.

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

(b) In general, the countries that do not have a BCG vaccination programme are high-income
countries that have a low number of cases of TB. In most of these countries, the vaccine is
given only to babies and children at high risk of developing TB.

Suggest one reason why a child in a country with a low number of cases of the disease could
be at a high risk of developing TB.

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

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

Table 3.1 shows the estimated incidence of TB for 2012 to 2016 for these income groups.

The incidence represents the number of new cases of TB occurring per 100 000 people in
one year. The new cases include the number of cases that have occurred again after a period
of recovery (relapse TB).

Table 3.1

incidence per 100 000 people

year
2012 2013 2014 2015 2016
income group
low 253 244 238 231 224
lower middle 244 240 236 232 227
upper middle 84 81 78 76 74
high 14 13 13 12 12

© UCLES 2020 9700/22/M/J/20

Describe the patterns and trends shown in Table 3.1.

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

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

(d) There is evidence that the BCG vaccine has also provided protection against the disease
leprosy.

Leprosy is caused by a bacterium that is closely related to the bacteria that cause TB.

Suggest why the BCG vaccine can also provide protection against leprosy.

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

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

(e) A baby can gain artificial active immunity to TB after having the BCG vaccine. A baby can
also gain natural passive immunity to TB.

State the differences between artificial active immunity and natural passive immunity.

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

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

[Total: 10]

© UCLES 2020 9700/22/M/J/20 [Turn over

4 Collagen is a major component of the cartilage found in some of the structures of the human gas
exchange system. Cells that synthesise and secrete the components of cartilage are known as
chondrocytes.

(a) Fig. 4.1 is a transmission electron micrograph of a chondrocyte.

Fig. 4.1

With reference to Fig. 4.1, explain two features of the chondrocyte that show how the cell is
adapted to its function.

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

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

(b) (i) Describe the distribution of cartilage in the human gas exchange system.

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

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

© UCLES 2020 9700/22/M/J/20

(ii) Outline the function of cartilage in the human gas exchange system.

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

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

gly glu arg gly glu gln gly ala pro gly

Fig. 4.2

(i) Name the type of covalent bond formed between the amino acids shown in Fig. 4.2.

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

(ii) Fig. 4.3 shows the molecular structure of the amino acid glycine (gly).

H H O
N C C
H H O H

Fig. 4.3

With reference to Fig. 4.2 and Fig. 4.3 and the function of collagen, explain how the
structure of a collagen polypeptide makes it suitable to form a collagen molecule.

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

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

[Total: 10]

© UCLES 2020 9700/22/M/J/20 [Turn over

5 In most plants, sucrose is the main sugar that is transported from sources to sinks.

(a) In the source, sucrose is transferred from a mesophyll cell to a phloem sieve tube through a
companion cell.

Describe and explain how the transfer of sucrose into a phloem sieve tube from a companion
cell can lead to the transport of the sugar to a sink.

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

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

(b) Fig. 5.1 shows part of one pathway that is used in plant cells to synthesise sucrose. The
enzyme sucrose synthase catalyses the transfer of glucose from UDPG (uridine diphosphate
glucose) to fructose.

sucrose synthase

UDPG + fructose UDP + sucrose

Fig. 5.1

The structure of UDPG is shown in Fig. 5.2.

uracil

glucose
ribose

Fig. 5.2

(i) Name the type of bond formed when sucrose is synthesised.

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

© UCLES 2020 9700/22/M/J/20

(ii) Explain why UDP can be described as a phosphorylated nucleotide.

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

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

(iii) Sucrose synthase acts by using an induced fit mechanism rather than a lock and key
mechanism.

With reference to sucrose synthase and the synthesis of sucrose, outline the difference
between the induced fit mechanism and lock and key mechanism of enzyme action.

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

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

© UCLES 2020 9700/22/M/J/20 [Turn over

The molecular structure of floridean starch has been described as an intermediate between
amylopectin and glycogen, with little or no amylose.

Describe the molecular structure of floridean starch by completing the passage.

Floridean starch is a polysaccharide composed of ..................................... monomers.

The monomers are joined by ..................................... and ..................................... linkages,

to give a branching structure that is less highly branched than

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

[Total: 15]

© UCLES 2020 9700/22/M/J/20

6 The mitotic cell cycle in dividing cells is very carefully controlled.

(a) Complete Table 6.1 to show the correct order of stages in the mitotic cell cycle.

Some of the stages have been completed for you.

Table 6.1

stage of cell cycle

G1 phase

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

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

...............................................
mitosis

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

telophase

cytokinesis

[3]

© UCLES 2020 9700/22/M/J/20 [Turn over

At various points during the mitotic cell cycle, checks are made. A cell goes through cell death
(apoptosis) if errors occur that cannot be repaired. This makes sure that the daughter cells
produced are genetically identical to each other and to the original cell.

Drugs have been developed that can inhibit the mitotic cell cycle and cause the cell to carry out
apoptosis. These drugs are used in the treatment of cancer.

(b) Vincristine and 5-fluorouracil are chemical compounds that act as cell cycle inhibitors and
can lead to apoptosis.

• Vincristine binds to spindle microtubules and prevents the spindle from carrying out its
function.
• 5-fluorouracil prevents the synthesis of thymine nucleotides.

Complete Table 6.2 to show which event in the cell cycle will occur when Vincristine or
5-fluorouracil are added to healthy dividing cells at the start of the interphase stage of the cell
cycle.

Place a tick (3) if the event will occur or a cross (7) if the event will not occur.

All boxes in the table should be completed.

Table 6.2

sister
event in cell chromosomes
cell enters chromatids
cycle S-phase line up at
prophase of move towards
completes spindle
mitosis opposite
compound equator
poles
Vincristine
5-fluorouracil

[2]

© UCLES 2020 9700/22/M/J/20

Fig. 6.1 is a photomicrograph of a blood smear of a person with one form of leukaemia, which
affects lymphocytes.

red blood cell

Fig. 6.1

Describe how:

• the blood smear shown in Fig. 6.1 differs from a blood smear of a healthy person
• the lymphocytes in a person with leukaemia, such as those shown in Fig. 6.1, differ from
those of a healthy person.

blood smear differences ............................................................................................................

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

lymphocyte differences ..............................................................................................................

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

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

[Total: 8]

© UCLES 2020 9700/22/M/J/20

BLANK PAGE

© UCLES 2020 9700/22/M/J/20

Cambridge International AS & A Level
* 2 2 9 5 0 2 5 1 5 6 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions October/November 2020

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INFORMATION
● The total mark for this paper is 60.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 20 pages. Blank pages are indicated.

DC (JC/CT) 185256/3
© UCLES 2020 [Turn over
2

Answer all questions.

1 Fig. 1.1 is a diagram drawn from a photomicrograph of a transverse section through part of a leaf.

The arrows in Fig. 1.1 show the movement of water through the cells of the leaf after it has left the
xylem.

C
B
A

X
P

Y
D

Fig. 1.1

(a) Water from the xylem can enter cell A and then moves to cells B and C without crossing their
cell walls.

The cell structures through which water passes from cell A to cell B are not visible in Fig. 1.1.

(i) Name the cell structures through which water passes from cell A to cell B without
crossing their cell walls.

..................................................................................................................................... [1]
© UCLES 2020 9700/22/O/N/20
3

(ii) Explain what causes water to move from cell B to cell C.

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

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

(iii) Name the pathway taken by water between cell A and cell C.

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

(b) Most of the water that arrives at the leaf passes to the external atmosphere.

With reference to Fig. 1.1, describe and explain the sequence of events occurring between
point P and point Q.

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

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

Calculate the magnification of the image.

Write down the formula used to make your calculation. Show your working.

formula

answer = × ......................................................... [3]

[Total: 10]

© UCLES 2020 9700/22/O/N/20 [Turn over

2 The treatment for people with active tuberculosis (TB) lasts six months and involves a combination
of antibiotics. This is usually very effective if the person has a susceptible (non-resistant) strain of
Mycobacterium tuberculosis, the causative organism of TB.

Table 2.1 summarises one recommended treatment strategy that involves a combination of
antibiotics.

Table 2.1

length of
antibiotic mode of action of antibiotic
treatment
enters bacterial cells and inhibits protein
rifampicin (R) 6 months
synthesis
prevents the synthesis of cell wall
isoniazid (H) 6 months
components known as mycolic acids
prevents mycolic acids from being added
ethambutol (E) first two months
to the cell wall

pyrazinamide (Z) first two months prevents the synthesis of fatty acids

(a) Susceptible strains of M. tuberculosis will be killed using any one of the antibiotics listed in
Table 2.1. However, combination treatment is preferred as it is one method that can be used
to reduce the impact to society of antibiotic resistance.

With reference to Table 2.1, explain how combination treatment for TB can help to reduce the
impact of antibiotic resistance compared to single antibiotic treatment.

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

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

© UCLES 2020 9700/22/O/N/20

Rifampicin binds tightly to an RNA polymerase molecule close to its active site. This affects the
activity of the enzyme.

(b) (i) RNA polymerase catalyses the formation of messenger RNA (mRNA) from DNA.

State the term for this process.

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

(ii) During the formation of RNA, a number of events occur that involve the action of RNA
polymerase.

Suggest ways in which rifampicin can affect the activity of RNA polymerase.

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

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

© UCLES 2020 9700/22/O/N/20 [Turn over

(c) RNA polymerase is composed of five different polypeptides. Gene rpoB codes for one of
these polypeptides known as the β-subunit.

One or more mutations in a specific region of rpoB result in strains of M. tuberculosis that
are resistant to rifampicin. In these strains, mutations often occur in two DNA triplets in this
region, in positions 526 and 531.

Table 2.2 summarises the results of an investigation into seven rifampicin-resistant strains,
A to G, that have amino acid changes for positions 526 and 531.

Table 2.2 includes:

• the change in the mRNA codon for position 526 or position 531
• the amino acid change that has occurred as a result of the mutation
• the minimum concentration of rifampicin required to inhibit growth of the bacterial
strain (MIC)
• the number of other mutations occurring within the specific region of rpoB.

Table 2.2

Key
. approximately H greater than or equal to G less than or equal to

number of
mRNA
codon amino acid MIC / other mutations
strain codon
involved change µg cm–3 in the specific
change
region

A 526 CAC UAC His Tyr G 50 0

B 526 CAC AAC His Asn H 100 1

C 526 CAC CGC His Arg . 50–75 2

D 526 CAC CGC His Arg H 100 3

E 526 CAC CGC His Arg . 50 3

526 CAC UUC

His ..............
F H 100 3
531 UCG UUG Ser Leu

526 CAC UAC

His ..............
G H 100 3
531 UCG UUC Ser Phe

© UCLES 2020 9700/22/O/N/20

(i) Complete Table 2.2 to show the amino acid changes that have occurred in strains
F and G.
[1]

(ii) With reference to Table 2.2, list the strains of M. tuberculosis that show the greatest
resistance to rifampicin.

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

(iii) Suggest reasons to explain why strains C, D and E show:

• resistance to rifampicin
• different levels of resistances to rifampicin.

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

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

[Total: 13]

© UCLES 2020 9700/22/O/N/20 [Turn over

3 Fig. 3.1 is a photomicrograph of a section through lung tissue.

ciliated epithelium

magnification × 40

Fig. 3.1

(a) State the feature visible in Fig. 3.1 that identifies the structure in the centre of the image as
the bronchus and list other visible features that help to confirm this identification.

feature to identify the bronchus ................................................................................................

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

other features ...........................................................................................................................

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

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

(b) Identify the structure labelled J in Fig. 3.1.

State the evidence visible in Fig. 3.1 that supports your answer.

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

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

Outline how goblet cells and cilia work together to maintain healthy lung tissue.

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

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

[Total: 7]

4 In the immune system, a plasma cell develops from an activated B-lymphocyte. Mature plasma
cells synthesise and secrete antibody molecules.

(a) Fig. 4.1 is a diagram of a transmission electron micrograph of a plasma cell.

Fig. 4.1

The plasma cell can be seen in greater detail using an electron microscope compared with
using a light microscope.

(i) Describe the extra detail of the nucleus that can be seen using an electron microscope.

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

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

(ii) Explain why cell structures, such as ribosomes and the rough and smooth endoplasmic
reticulum, cannot be seen using a light microscope.

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

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

(b) The transition from the activated B-lymphocyte to the fully mature plasma cell requires a
number of mitotic cell cycles to occur. This process, which is known as clonal expansion,
results in a large number of genetically identical plasma cells.

Fig. 4.2 describes events, A to F, that occur during the mitotic cell cycle of the B-lymphocyte.

A centrioles replicate

B DNA polymerase catalyses the formation of phosphodiester bonds

C condensation of chromosomes

D nuclear envelope reassembles around each set of daughter chromosomes

E centromeres move towards poles

F chromosomes line up at spindle equator

Fig. 4.2

Table 4.1 lists the stages occurring during one cell cycle of the B-lymphocyte. These stages
are not in the correct order.

Table 4.1

correct letter
stage of cell cycle
from Fig. 4.2

G2 phase

metaphase F

cytokinesis

prophase

S phase

anaphase

G1 phase

telophase

Complete Table 4.1 by writing the letter of the event described in Fig. 4.2 that correctly
matches the stage of the cell cycle listed.

Leave a blank space if there is no matching description for the stage in the list. Use each
letter once only.

One of the letters in Table 4.1 has already been added for you.
[5]

(c) Clonal expansion also results in the production of memory B-lymphocytes.

Explain the importance of clonal expansion and the production of memory B-lymphocytes in
providing protection for a person against an infectious disease.

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

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

(d) Myasthenia gravis is an example of a disease where the immune system fails to distinguish
between self and non-self.

Explain what is meant by this statement.

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

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

[Total: 15]

5 Sucrose phosphorylase is an enzyme found in some species of bacteria. One function of this
enzyme is for the production of compounds that help to protect the cell from harmful osmotic
changes in the external environment.

Fig. 5.1 shows the reversible reaction that takes place within the bacterial cell.

sucrose
phosphorylase
sucrose + Pi α-glucose-1-phosphate + X
inorganic
phosphate reducing
sugar

Fig. 5.1

(a) Name reducing sugar X in Fig. 5.1.

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

(b) In the absence of sucrose phosphorylase as a catalyst, the reaction shown in Fig. 5.1 would
take too long to occur to allow the bacterial cell to function efficiently.

Explain why the reaction shown in Fig. 5.1 proceeds at a much faster rate in the presence of
the enzyme.

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

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

(c) An enzyme that catalyses a reaction of commercial interest needs to be investigated to see if
it is suitable for use in industry.
For example:
• immobilised enzymes may be used as they have a longer shelf-life than the enzyme
free in solution
• many industrial reactions are carried out at higher temperatures to minimise
contamination of products by microorganisms.

Fig. 5.2 shows the results of an investigation to compare the activity of sucrose phosphorylase
free in solution (free enzyme) with immobilised sucrose phosphorylase (immobilised enzyme)
at different pHs.

Fig. 5.3 shows the activity of the free enzyme and immobilised enzyme at different
temperatures.

100

relative sucrose
phosphorylase
activity
/% 60

20
2 4 6 8
pH
Key
free enzyme
immobilised enzyme

Fig. 5.2

100

relative sucrose
phosphorylase
activity
/% 60

20
20 40 60 80
temperature / °C
Key
free enzyme
immobilised enzyme

Fig. 5.3

With reference to the results shown in Fig. 5.2 and Fig. 5.3, discuss which sucrose
phosphorylase enzyme, free or immobilised, is better for use in industrial reactions.

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

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

[Total: 7]

6 (a) Fig. 6.1 shows an oxygen dissociation curve for adult human haemoglobin.

100

percentage 60
saturation of
haemoglobin 40

0
0 2 4 6 8 10 12 14
partial pressure
of oxygen / kPa

Fig. 6.1

An increase in the partial pressure of carbon dioxide (pCO2) in respiring tissue causes the
Bohr effect.

(i) Sketch on Fig. 6.1 to show how the Bohr effect changes the oxygen dissociation curve.
[1]

(ii) Explain how an increase in pCO2 produces the Bohr effect and state the benefit of this
effect for the tissue.

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

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

(b) Carbon dioxide (CO2) is transported across the cell surface membrane of the red blood cell
using a different mechanism to the transport of hydrogen carbonate ions (HCO3–).

Name the different mechanisms of transport used for CO2 and for HCO3– and explain why
they are transported across the membrane by different mechanisms.

CO2 ...........................................................................................................................................

HCO3– .......................................................................................................................................

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

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

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

[Total: 8]

BLANK PAGE

Cambridge Assessment International Education
Cambridge International Advanced Subsidiary and Advanced Level
* 1 8 8 7 7 8 4 2 9 8 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions February/March 2019
1 hour 15 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.

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 an HB pencil for any diagrams or graphs.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.

Answer all questions.

Electronic calculators may be used.

You may lose marks if you do not show your working or if you do not use appropriate units.

At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.

This document consists of 16 printed pages.

Answer all questions.

1 Fig. 1.1 and Fig. 1.2 are photomicrographs of sections through the leaves of two different plants.

Fig. 1.1 is a photomicrograph of a section through a leaf of Cornish heath, Erica vagans.

C A

Fig. 1.1

Fig. 1.2 is a photomicrograph of a section through a leaf of Himalayan cedar, Cedrus deodara.

C
A

Fig. 1.2

Fig. 1.1 and Fig. 1.2 are not shown at the same magnification.

(a) Cells labelled A, B and C in Fig. 1.1 and Fig. 1.2 each form a different tissue.

Name each tissue formed.

tissue formed from A ................................................................................................................

tissue formed from B ................................................................................................................

tissue formed from C ................................................................................................................

[3]

(b) Erica vagans and Cedrus deodara are xerophytic plants.

With reference only to xerophytic features, describe the differences between the leaves of
E. vagans and C. deodara visible in Fig. 1.1 and Fig. 1.2.

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

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

(c) Transpiration is a consequence of gas exchange in leaves.

Explain why the rate of transpiration is greater during the day than during the night.

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

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

[Total: 9]

2 In mammalian red blood cells, carbonic anhydrase has an important role in the transport of carbon
dioxide.

Carbonic anhydrase is an enzyme.

(a) Outline the features of an enzyme.

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

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

(b) Complete Fig. 2.1 to show the reversible reaction involving carbonic anhydrase that takes
place within red blood cells.

body tissues

lungs

Fig. 2.1
[2]

(c) A ribbon structure of a molecule of carbonic anhydrase is shown in Fig. 2.2. The zinc ion is
associated with the active site of the enzyme and is essential for the enzyme to function.

zinc ion

Fig. 2.2
The molecule of carbonic anhydrase has primary, secondary and tertiary structure.

Explain the extent to which Fig. 2.2 shows the primary, secondary and tertiary structure of
carbonic anhydrase.

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

............................................................................................................................................. [4]
[Total: 10]
© UCLES 2019 9700/22/F/M/19 [Turn over
6

3 In 2015, the World Health Organization (WHO) published the Global Technical Strategy for Malaria
2016–2030. The aim of this global strategy, which follows on from the 2008 Global Malaria Action
Plan (GMAP), is to make progress in the control and elimination of malaria.

Both the global strategy and GMAP aim to reduce:

• the case incidence (number of new cases each year) of malaria

• the mortality rate (number of deaths each year) from malaria.

(a) Fig. 3.1 shows data for the four countries in the WHO Western Pacific Region that had the
highest proportion of cases of malaria in 2015.

For each of these four countries, the percentage change in the case incidence and the
percentage change in the mortality rate over the five-year period from 2010 to 2015 are
shown.

+100
Key
+80 case incidence

+60 mortality rate

+40

+20
percentage
0
change

–20

–40

–60

–80

–100
Lao Cambodia Solomon Papua
People’s Islands New
Democratic Guinea
Republic
(Lao PDR)

Fig. 3.1

(i) With reference to Fig. 3.1, describe the progress made in the control of malaria in the
four countries between 2010 and 2015.

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

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

(ii) All the countries shown in Fig. 3.1 supplied households at risk of malaria with
insecticide-treated nets (ITNs). This is one of the recommendations in the GMAP and the
global strategy.

Describe and explain the role of ITNs.

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

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

(b) Another recommendation of the global strategy is to carry out rapid diagnostic testing (RDT)
of individuals who may have malaria. This involves testing human blood samples for the
presence of proteins specific to Plasmodium. Test sticks can be used.

Table 3.1 contains information about two RDT test sticks.

Table 3.1

Plasmodium protein species of Plasmodium

test stick
tested for that produce the protein
P. vivax
pLDH
P. falciparum
1 (parasite lactate
P. ovale
dehydrogenase)
P. malariae
HRP-2
2 P. falciparum only
(histidine-rich protein 2)

Some details of the design of these RDT test sticks are shown in Fig. 3.2.

area with immobilised area containing mobile monoclonal

monoclonal antibodies antibodies labelled with a coloured dye

test window direction of movement of blood sample blood sample

added to this area

Fig. 3.2

The immobilised monoclonal antibodies in the test window are not visible.

If the blood sample contains a Plasmodium protein that can be detected by the RDT test
stick:

• the mobile monoclonal antibodies bind to one part of the protein

• the immobilised monoclonal antibodies bind to another part of the protein

• a coloured line in the test window indicates a positive result for the protein.

(i) With reference to Table 3.1 and Fig. 3.2, explain why test stick 1 and test stick 2 will
contain different mobile monoclonal antibodies.

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

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

(ii) Two blood samples were removed from a person. One sample was added to test stick 1
and the other sample was added to test stick 2.

With reference to Table 3.1 and Fig. 3.2, explain what can be diagnosed for this person
from a positive result for test stick 1 and a negative result for test stick 2.

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

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

[Total: 10]

4 In a double circulatory system, blood passes through the heart twice in one complete circuit of the
body. The complete circuit consists of the pulmonary circulation and the systemic circulation.

(a) Fig. 4.1 is a diagram of a vertical section through the mammalian heart. The differences in the
thickness of cardiac muscle in the walls of the four chambers of the heart are shown.

right atrium
left atrium

left ventricle
right ventricle

cardiac muscle

Fig. 4.1

Explain, with reference to their functions, the difference in the thickness of the walls of the left
ventricle and right ventricle of the heart.

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

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

(b) The alveolus is the gas exchange surface in mammals. For efficient oxygen uptake, a steep
diffusion gradient is maintained between the alveolar air and the blood.

Suggest how the steep diffusion gradient for oxygen is maintained at the gas exchange
surface.

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

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

(c) Compared to when they were non-smokers, the ability of people who smoke tobacco to
deliver oxygen to their body tissues is reduced. Two causes of this reduction include:

• a decrease in the volume of air per breath moving towards the alveoli
• a decrease in the ability of red blood cells to carry oxygen.

(i) Suggest one reason why smoking tobacco, even after only a short time, may cause a
decrease in the volume of air per breath moving towards the alveoli.

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

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

(ii) Explain why smoking tobacco causes a decrease in the ability of red blood cells to carry
oxygen.

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

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

[Total: 8]

5 Human prolactin (hPRL) is a globular protein. It is a single polypeptide composed of 199 amino
acids. The protein is transported in the bloodstream and has an effect only on cells that have a cell
surface membrane protein known as PRLR.

One effect of hPRL is to stimulate cells in the mammary glands to produce breast milk. Cells that
have been stimulated by hPRL need more glucose and therefore the passive uptake of glucose
increases.

(a) State one reason why the cells in the mammary glands that have been stimulated by hPRL
need more glucose.

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

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

(b) An experiment was carried out to investigate the movement of glucose and hPRL across
Visking tubing membrane.

• A short section of Visking tubing, tied at both ends and containing distilled water,
was placed into a beaker containing a solution of glucose and hPRL.
• After 20 minutes, separate samples of the solution in the Visking tubing and the
solution in the beaker were each tested for the presence of protein and reducing
sugar.

A summary of the methods used, the experimental results and the deductions made are
shown in Table 5.1.

Table 5.1

sample method used colour obtained after testing deduction

solution
protein absent from
in Visking
biuret solution solution in Visking tubing
tubing
added to
solution in sample protein present in
beaker solution in beaker

solution Benedict’s
reducing sugar present in
in Visking solution
solution in Visking tubing
tubing added to
sample and
solution in mixture reducing sugar present in
beaker heated in a solution in beaker
water-bath

(i) Complete the column in Table 5.1 headed colour obtained after testing. [2]

(ii) With reference to the deductions made in Table 5.1, explain the movement of hPRL and
reducing sugar across Visking tubing membrane.

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

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

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

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

(d) The production of milk by the cells of the mammary glands involves the action of several
different enzymes. The cell surface membranes of these cells contain the membrane protein
PRLR.

Fig. 5.1 shows an outline summary of hPRL involvement in the production of breast milk.

synthesis and release

of hPRL capillary

anterior pituitary cells at

the base of the brain hPRL

membrane
protein PRLR

milk
mammary
gland cells
milk

not to scale

Fig. 5.1

Explain why the production of breast milk can be described as an example of a cell signalling
process.

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

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

6 Plant and animal cells carry out mitosis to form two genetically identical cells from one original
cell.

(a) State other reasons why mitosis is important in both plants and animals.

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

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

(b) Plant cells require microtubules to form structures that are needed for mitosis.

Name one of these structures.

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

(c) During the mitotic cell cycle, free nucleotides are used for the synthesis of both types of
nucleic acid: RNA and DNA.

Complete sentences A, B, C and D to provide information about nucleotides and the synthesis
of nucleic acids.

Write the correct term in the spaces provided in each sentence.

A Each nucleotide has three main components: a ................................................... group,

a ................................................... (5 carbon) sugar and a nitrogenous organic base.

B The nitrogenous organic base of a nucleotide is either a purine or

a ................................................... .

C In a DNA nucleotide, the sugar is deoxyribose and in an RNA nucleotide the sugar

is ................................................... .

D The synthesis of RNA from a template strand of DNA is known as

................................................... .
[5]

(d) A virus named Pandoravirus salinus was discovered in 2013 by French scientists.

The virus was so large that the scientists initially thought that P. salinus was a bacterium.

P. salinus was confirmed to be a virus after further research.

(i) List three key features of viruses.

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

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

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

(ii) The dimensions of viruses are usually stated in nanometres (nm).

As P. salinus is so big, it has been described as 1 µm long and 0.5 µm wide.

Convert the width of P. salinus to nanometres.

width = .................................................... nm [1]

[Total: 12]

Cambridge Assessment International Education
Cambridge International Advanced Subsidiary and Advanced Level
* 1 7 8 4 3 0 6 3 8 5 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions May/June 2019
1 hour 15 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.

READ THESE INSTRUCTIONS FIRST

Answer all questions.

Electronic calculators may be used.

You may lose marks if you do not show your working or if you do not use appropriate units.

At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.

This document consists of 15 printed pages and 1 blank page.

Answer all questions.

1 Fig. 1.1 is a photomicrograph of a low power image of part of the common sunflower,
Helianthus annuus. Fig. 1.1 is a transverse section.

Fig. 1.1

(a) State, with a reason, whether Fig. 1.1 shows a section through the root or the stem of
H. annuus.

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

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

(b) Cell type A in Fig. 1.1 has a large central vacuole.

Suggest, with reasons, the role of the tissue formed by this type of cell.

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

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

(i) Name structure B.

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

(ii) The actual length of structure B is 650 µm.

State the actual length of structure B in mm.

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

(d) When structure B is observed at a higher magnification, more detail of xylem vessel elements
and phloem sieve tube elements can be seen.

Outline the differences in the structure of a xylem vessel element and a phloem sieve tube
element.

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

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

[Total: 8]

2 Some tissues of the gas exchange system include cells that are able to produce and secrete
mucins. Mucins are stored in vesicles in these cells, ready for secretion. Once outside the cell,
mucins adsorb water to form mucus.

(a) Name the structures in the gas exchange system that produce and secrete mucins.

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

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

(b) Mucins are described as glycosylated proteins. The process of glycosylation involves the
addition of sugar components after polypeptides are synthesised.

Suggest one location in the cell where glycosylation of mucin could occur.

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

translation exocytosis glycosylation transcription

Complete Table 2.1 by writing the processes in the correct order in which they would take
place.

Table 2.1

first
process

second
process

third
process

fourth
process

[2]

(d) Chloride ions move out of the mucin-producing cells at the same time as mucin is secreted.

Suggest and explain how the exit of chloride ions helps the formation of mucus from mucin.

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

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

(e) The gas exchange system includes some cells that are able to divide by mitosis.

Explain why it is important to have these cells in the gas exchange system.

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

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

[Total: 11]

3 Fig. 3.1 is a photomicrograph of human blood cells from a healthy individual who lives at sea level.
The cells labelled C, D and E are white blood cells.

E C

red blood cell

Fig. 3.1

(a) Name cells C, D and E.

C ...............................................................................

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

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

(b) In humans, an increase in the white blood cell count can be associated with leukaemias and
with infectious diseases, such as measles.

Chronic lymphocytic leukaemia (CLL) is a type of cancer that starts in the bone marrow. In
the early stages, many people with CLL feel well. The disease is sometimes diagnosed by
chance during a routine blood analysis, when a high white blood cell count is noticed. Many
of these white blood cells are only partially mature.

(i) Suggest why CLL starts in the bone marrow and not in any other location in the body.

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

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

(ii) Explain why a high white blood cell count is a feature of measles and of CLL.

measles .............................................................................................................................

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

CLL ....................................................................................................................................

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

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

(i) Describe and explain the passage of oxygen across the cell surface membrane of the
red blood cell.

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

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

(ii) At a high altitude, the partial pressure of oxygen in the atmosphere is lower than at sea
level. If a person travels from low altitude to high altitude and remains there for a few
weeks, the red blood cell count increases.

Explain why the body needs to respond to high altitude by increasing the number of red
blood cells.

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

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

(d) Polypeptide synthesis occurs before a red blood cell is released into the circulation.

The HBB gene codes for the β-globin polypeptide of haemoglobin.

There are two alleles of HBB, known as HbA and HbS.

Describe the difference between the HbA allele and the HbS allele and state how this
difference affects:

• the β-globin polypeptide

• the haemoglobin molecule.

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

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

[Total: 17]

4 The bacterium Vibrio cholerae is the causative organism of the infectious disease cholera.

V. cholerae has structural features typical of all bacterial cells. It also has a flagellum for movement.

(a) Fig. 4.1 is an outline drawing of V. cholerae.

Complete Fig. 4.1 by drawing and labelling the structures found in V. cholerae.

flagellum

Fig. 4.1

[4]

(b) The World Health Organization (WHO) collects data about cholera from the 194 countries
that are members of the World Health Assembly (WHA).

In 2015:
• there were cases of cholera in 42 of the member countries of the WHA
• the total number of cases of cholera reported was 172 454
• there were deaths as a result of cholera in 23 of these countries
• the total number of deaths from cholera reported was 1304.

The case fatality rate for cholera is the proportion of cases of cholera that results in death
within a particular time period.

A country with cases of cholera that are properly treated should have a case fatality rate of
less than 1%.

(i) Calculate the case fatality rate for the 42 member countries of the WHA for 2015.

Give your answer to the nearest 0.1%.

case fatality rate = ..................................................... % [1]

(ii) Many of the 23 countries reporting deaths from cholera in 2015 had a case fatality rate of
less than 1%.

However, two of the 23 countries had case fatality rates greater than 5%.

Suggest two explanations for the higher case fatality rate in these two countries.

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

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

(i) Explain why an earthquake may lead to a cholera outbreak.

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

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

(ii) Fig. 4.2 shows data about cholera collected by WHO over a period of 8 years, from 2008
to 2015. These data include:

• the total number of cases of cholera for each year

• the number of countries in each year that had cases of cholera.

700 000 70

600 000 60

500 000 50
number number of
of cases countries
400 000 40

300 000 30

200 000 20 Key

number of
100 000 10 cases
number of
0 0 countries
2008 2009 2010 2011 2012 2013 2014 2015
year

Fig. 4.2

Comment on the trends shown in Fig. 4.2.

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

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

[Total: 11]

5 Cells contain carbohydrates, proteins, lipids and nucleic acids.

(a) Fig. 5.1 is a list of biological molecules, some of which are components of larger molecules.

cellulose
thymine nucleotide
α-glucose
β-glucose
messenger RNA
glycogen
glycine
α-globin

Fig. 5.1

Complete Table 5.1 by using only the molecules listed in Fig. 5.1.

• Each example can be written under one or more correct headings.

• All the examples in Fig. 5.1 should appear at least once in Table 5.1.

Table 5.1

examples
monomers polymers monosaccharides polysaccharides

[5]

(b) Explain how the structure of phospholipids allows the formation of the phospholipid bilayer of
cell membranes.

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

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

[Total: 8]

6 Catalase is an enzyme that catalyses the breakdown of hydrogen peroxide, which is a waste
product of cell metabolism.

The reaction catalysed by catalase is shown in Fig. 6.1.

catalase
2H2O2 2H2O + O2

Fig. 6.1

(a) A student carried out two experiments to investigate the progress of the reaction shown in
Fig. 6.1. Potato tissue was used as the source of the enzyme.

Six pieces of potato were cut, each measuring 20 mm × 10 mm × 10 mm.

In the first experiment, hydrogen peroxide solution was added to three of the pieces of potato
tissue and the progress of the reaction was measured.

Fig. 6.2 shows how the first experiment was set up.

syringe containing
H2O2 solution

potato

Fig. 6.2

(i) Suggest how the progress of the reaction could be measured.

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

..................................................................................................................................... [2]
© UCLES 2019 9700/22/M/J/19
15

(ii) In the second experiment, the student cut each of the three remaining pieces of potato to
obtain six pieces, each measuring 10 mm × 10 mm × 10 mm.

Using exactly the same conditions, the student measured the progress of the reaction
and obtained different results to the first experiment.

Explain why the results of the second experiment were different from the results of the
first experiment.

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

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

(b) The student then investigated the effect of temperature on the activity of catalase.

On Fig. 6.3, sketch a curve to show how temperature affects the activity of an enzyme such
as catalase.

rate of
reaction

temperature / °C

Fig. 6.3
[1]

[Total: 5]

BLANK PAGE

Cambridge Assessment International Education
Cambridge International Advanced Subsidiary and Advanced Level
* 1 1 2 9 6 8 8 0 8 5 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions October/November 2019
1 hour 15 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.

READ THESE INSTRUCTIONS FIRST

Answer all questions.

Electronic calculators may be used.

You may lose marks if you do not show your working or if you do not use appropriate units.

At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.

This document consists of 15 printed pages and 1 blank page.

Answer all questions.

1 Fig. 1.1 is a photomicrograph of a transverse section through the stem of creeping buttercup,
Ranunculus repens.

Fig. 1.1

(a) Draw one label line on Fig. 1.1 to indicate one precise location where phloem sieve tubes
occur. [1]

(b) State the role of phloem sieve tubes.

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

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

(c) A good quality plan diagram of Fig. 1.1 will show only the tissues in the stem in their correct
location and in the correct proportions.

(i) State the name of the tissue that forms the outer layer of the stem section of R. repens in
Fig. 1.1.

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

(ii) State the piece of equipment that can be used in the light microscope to work out the
correct proportions of the tissues.

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

(d) Draw a diagram in the space provided to show the structure of a typical plant cell.

Label your diagram with the name of any structures that are found only in plant cells.

Do not label any structures that are also found in animal cells.

[5]

[Total: 10]

2 People who smoke tobacco are at an increased risk of developing non-infectious diseases of the
gas exchange system and the cardiovascular system.

In 2004, a study was carried out on the most popular brands of filter cigarettes from each of the six
World Health Organization (WHO) regions.

In this study, the smoke passing through the filter was analysed for the tar, nicotine and carbon
monoxide (CO) content for each brand of cigarette. For each WHO region, the mean content of
tar, nicotine and carbon monoxide of the different brands of cigarette was calculated.

The results are shown in Fig. 2.1.

Key to WHO regions

AFRO = African Region
AMRO = Region of the Americas
EMRO = Eastern Mediterranean Region
EURO = European Region
SEARO = South-East Asia Region
WRPO = Western Pacific Region

20
Tar
18
Nicotine (×10)
16 CO

mg per
10
cigarette
8

0
AFRO AMRO EMRO EURO SEARO WRPO

WHO Region

Fig. 2.1

(a) With reference to Fig. 2.1, list the two WHO regions where smokers are at the highest risk of
developing diseases of the gas exchange or cardiovascular systems.

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

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

(b) With reference to Fig. 2.1, explain why smoking a popular brand of cigarette from the AFRO
region is more likely to increase the risk of blood clots forming than smoking a popular brand
of cigarette from the EURO region.

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

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

Describe and explain why cigarette smoking leads to a decrease in the supply of oxygen to
body tissues.

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

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

[Total: 7]

3 A red blood cell goes through a number of stages in the bone marrow before it is released into the
circulation to carry out its role of oxygen transport.

Fig. 3.1 is a transmission electron micrograph of developing red blood cells in the bone marrow.
Each cell is known as an erythroblast.

Fig. 3.1

(a) Fig. 3.1 shows erythroblasts at a higher magnification than can be obtained using the light
microscope.

Explain the advantages of using an electron microscope to obtain images such as that in
Fig. 3.1.

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

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

(b) Describe the differences between an erythroblast and a mature red blood cell.

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

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

(i) Complete Table 3.1 to:

• name three organelles (cell structures) that are involved in the synthesis of a fully
functioning protein

• state one way in which the named organelle is involved in protein synthesis.

Table 3.1

organelle how the organelle is involved in protein synthesis

[3]

(ii) Fig. 3.2 shows a reversible reaction that takes place within red blood cells.

CO2 + H2O H2CO3

Fig. 3.2

Name the protein that catalyses the reaction shown in Fig. 3.2.

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

The SPTB gene codes for a protein that provides stability and support to the cell surface membrane
of the red blood cell.

Mutations in SPTB result in red blood cells that are spherical in shape. This mutation leads to a
disease known as spherocytosis type 2.

(d) Suggest why a person with spherocytosis type 2 has a reduced ability to take up oxygen in
the pulmonary capillaries compared with a person who has normal red blood cells.

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

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

(e) Increases in the water potential of the blood plasma have greater effects on red blood cells in
people with spherocytosis type 2 than on normal red blood cells.

Compare and explain the effects of an increase in the water potential of blood plasma on
spherocytosis type 2 red blood cells and normal red blood cells.

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

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

[Total: 14]

4 Carbohydrates, proteins and nucleic acids are types of biological molecule. Within each type,
there are examples of molecules that can be described as polymers.

(a) A polymer is a large molecule composed of smaller repeating molecules known as monomers.

Complete Table 4.1 to produce a summary of some named biological polymers.

Table 4.1

type of bond between

polymer constituent monomer
monomers

amylose glucose

cellulose glucose

collagen peptide

DNA DNA nucleotide

glycogen glycosidic

[4]

(b) Explain why an amylose molecule and a cellulose molecule have very different structures,
even though they both have glucose as the constituent monomer.

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

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

(c) Polymerisation of DNA nucleotides occurs during the semi-conservative replication of a

molecule of DNA during interphase.

Describe the semi-conservative replication of DNA.

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

............................................................................................................................................. [5]

[Total: 11]

5 Countries that have a high number of cases of malaria also have problems with diseases caused
by bacteria. This means that many people in these countries are prescribed antibiotics, such as
penicillin, for the treatment of bacterial infections.

(a) Outline how penicillin acts on bacterial cells.

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

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

The female Anopheles mosquito is the vector of the Plasmodium pathogen that causes malaria.
The insect takes in Plasmodium when feeding on blood from an infected person. At a later stage
the insect can transmit the pathogen when taking a blood meal from an uninfected person.

(b) Name one of the four species of Plasmodium that can cause malaria.

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

Suggest why there is a difference in this feeding behaviour between male and female
Anopheles.

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

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

(d) Research has shown that Plasmodium is not always transmitted to uninfected people.

Two main reasons for this have been suggested.

• The immune system of mosquitoes kills Plasmodium while it is still in the gut.

• Bacteria living in the gut of mosquitoes compete with Plasmodium so it does not survive
to continue its life cycle.

A study was carried out to see if taking antibiotics affects the risk of transmission of malaria.

Some observations and results of the study are summarised in Fig. 5.1.

individuals with malaria are individuals with malaria are

taking antibiotics not taking antibiotics

Anopheles mosquitoes take blood Anopheles mosquitoes take blood

meals meals

higher survival rate of Plasmodium lower survival rate of Plasmodium

in gut of Anopheles in gut of Anopheles

Fig. 5.1

Suggest explanations for the results shown in Fig. 5.1 and comment on the importance of
these results for doctors working in countries that have malaria and a high number of bacterial
infections.

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

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

(e) After many years of intense research and development, WHO reported in 2016 that a pilot
vaccination programme would be trialled between 2017 and 2020.

The programme uses a vaccine acting against the most widespread species of Plasmodium.

Explain the difficulties faced by researchers in developing a malaria vaccine.

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

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

[Total: 12]

6 Telomerase is an enzyme that is important in maintaining the telomeres that are located at the
ends of chromosomes.

(a) Explain the importance of telomeres.

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

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

(b) Suggest why telomerase is present in much higher quantities in stem cells and cancer cells
than in other cell types.

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

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

(c) Studies suggest that telomerase is a flexible molecule when binding its substrate. The active
site changes its shape slightly to allow the formation of the enzyme-substrate complex.

Name the theory that describes this mode of enzyme action.

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

(d) An investigation was carried out into the effect of substrate concentration on the activity of
telomerase.

The results are shown in Fig. 6.1.

rate of
reaction
3
/ arbitrary
units

0
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
substrate concentration / μmol dm–3

Fig. 6.1

With reference to Fig. 6.1, explain the difference in the rates of reaction obtained for telomerase
at a substrate concentration of 0.2 μmol dm−3 compared with a substrate concentration of
1.6 μmol dm−3.

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

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

[Total: 6]

BLANK PAGE

Cambridge International Examinations
Cambridge International Advanced Subsidiary and Advanced Level
* 7 2 9 0 1 0 1 7 1 1 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions February/March 2018
1 hour 15 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.

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 an HB pencil for any diagrams or graphs.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.

Answer all questions.

Electronic calculators may be used.

You may lose marks if you do not show your working or if you do not use appropriate units.

At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.

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

Answer all the questions.

1 Fig. 1.1 is an electron micrograph of part of a eukaryotic cell.

X Y
mitochondrion
×47 000

Fig. 1.1

(a) State how it is possible to deduce that Fig. 1.1 is a transmission electron micrograph and not
a scanning electron micrograph.

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

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

(b) Both the Golgi body and the rough endoplasmic reticulum are part of the internal network of
membranes in cells.

Outline structural features shown in Fig. 1.1 that identify G as the Golgi body and not the
rough endoplasmic reticulum.

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

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

Write down the formula that you will use to make your calculation. Give your answer to the
nearest whole nanometre (nm).

formula

actual diameter ................................... nm

(d) The inner and outer membranes of the mitochondrion have a fluid mosaic structure similar to
other cell membranes. They are both approximately 6 to 7 nanometres (nm) thick.

(i) Outline the fluid mosaic model of membrane structure.

There is space below for a diagram.

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

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

(ii) The inner and outer membranes of the mitochondrion differ in the detail of their
membrane components. The inner membrane is also much less permeable than the
outer membrane.

Suggest one way in which the structure of the inner membrane may differ from that of
the outer membrane to produce a less permeable inner membrane.

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

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

[Total: 9]

2 The main cause of tuberculosis (TB) in humans is the bacterium Mycobacterium tuberculosis.
Most cases of the disease involve the lungs. The bacterium can enter cells and remain inactive in
a latent (dormant) state. However, the bacterium can become active to produce symptoms of the
disease.

In a person with active TB, the pathogen can be present in airborne droplets that are exhaled.
Generally, a healthy person who inhales these droplets has effective defence mechanisms in the
gas exchange system to prevent infection.

(a) One example of a defence mechanism against pathogens in the gas exchange system
involves the action of macrophages.

(i) State the location in the body where macrophages have their origin.

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

(ii) Describe the mode of action of a macrophage.

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

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

(iii) It is sometimes possible for M. tuberculosis to survive within macrophages.

Suggest one way in which M. tuberculosis may survive within a macrophage.

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

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

(b) A healthy person has other defence mechanisms in the gas exchange system to prevent
bacteria entering cells.

Describe these defence mechanisms and explain how bacteria in inhaled air are prevented
from entering cells of the gas exchange system.

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

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

(c) In people with a weakened immune system, M. tuberculosis can infect other organs and
tissues, such as the kidneys and joints.

Suggest how the bacteria may spread from the lungs to other organs.

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

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

(d) TB in humans can be caused by another species of bacterium, M. bovis.

State the mode of transmission of this pathogen to humans.

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

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

(e) The standard treatment for TB continues for six months and initially involves the use of four
different antibiotics.

If no antibiotic resistance is detected, the treatment is reduced to two of the four antibiotics.
The two antibiotics used are rifampicin and isoniazid.

Suggest the benefits of beginning the treatment with four different antibiotics.

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

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

Multidrug-resistant TB (MDR-TB) occurs if resistance develops to rifampicin and isoniazid.

The treatment for MDR-TB can last up to 30 months and involves different antibiotics to the
standard treatment.

Table 2.1 shows the number of reported cases of TB and MDR-TB in the South-East Asia region
between 2005 and 2014, as published by the World Health Organization (WHO).

Table 2.1

total number of reported total number of reported

year
cases of TB cases of MDR-TB
2005 1 947 603 68
2006 2 104 673 779
2007 2 202 149 918
2008 2 287 803 1 717
2009 2 328 230 2 560
2010 2 332 779 4 263
2011 2 358 127 6 615
2012 2 331 455 14 957
2013 2 297 033 18 384
2014 2 580 605 17 386

(f) State the trends shown in Table 2.1.

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

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

(g) TB is a disease of global importance.

Discuss the factors influencing the trends shown in Table 2.1.

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

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

[Total: 17]

3 The unicellular fungus Kluyveromyces lactis is found in dairy products. It is a safe microorganism
to culture for the extraction of the enzyme lactase. Lactase catalyses the breakdown of lactose, a
sugar found in milk.

The reaction catalysed by lactase is summarised in Fig. 3.1.

CH2OH CH2OH
CH2OH O CH2OH O
H H H H
O H O H
OH OH OH
H O OH H lactase H OH H
OH + R + OH OH
OH H OH H
H H H H
H OH H OH
H OH H OH product S
lactose galactose

Fig. 3.1

(a) Describe the reaction that is catalysed by lactase. Use Fig. 3.1 to help you.

In your answer, identify R and product S.

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

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

(b) On a commercial scale, immobilised lactase can be used to produce lactose-free milk.

One of the products of the reaction shown in Fig. 3.1 acts as an inhibitor of lactase. This is an
example of product inhibition.

(i) Suggest why product inhibition is useful in K. lactis when lactase is acting as an
intracellular enzyme, but can be a disadvantage when extracted lactase is used free in
solution for the production of lactose-free milk.

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

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

(ii) Suggest how using immobilised lactase in a commercial application helps to reduce the
problem of product inhibition.

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

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

(iii) The first large-scale production of lactose-free milk with an immobilised enzyme used
lactase trapped in cellulose triacetate fibres.
Suggest one feature of cellulose triacetate that makes it useful as an immobilising
material.

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

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

Outline how the progress of an enzyme-catalysed reaction can be investigated experimentally.

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

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

[Total: 11]

4 Fig. 4.1 is a diagram of a section through part of a young root.

soil particle film of water

cortex

Fig. 4.1

(a) Describe the pathways by which water passes from the soil to the cells of the cortex shown in
Fig. 4.1.

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

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

(b) There is a greater density of mitochondria in the cytoplasm of cell X than in the cytoplasm of
a cell of the cortex.

Suggest why this is so.

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

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

5 (a) The sinoatrial node (SAN) and the atrioventricular node (AVN) are two regions of the heart.

Outline the roles of the SAN and the AVN in the initiation and control of heart action.

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

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

(b) Fig. 5.1 shows features that are observed in transverse sections of the three main types of
blood vessel.

blood vessel

wall of three layers wall of one layer

thin wall relative to thick wall relative to

lumen diameter lumen diameter

D ................................. E ................................. F .................................

Fig. 5.1

(i) Complete Fig. 5.1 by stating the type of blood vessel indicated by D, E and F. [1]

(ii) The inner layer of the walls of D and E is composed of endothelial tissue.
List two structural features of this tissue.

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

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

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

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

6 In a dividing cell, DNA replication occurs before mitosis.

(a) Steps in DNA replication are outlined in Fig. 6.1.

Complete Fig. 6.1 by filling in the gaps using the most appropriate terms.

1 Helicase enzyme allows the DNA double helix to unwind and the hydrogen
bonds between the two strands to break, exposing the four bases,

............................................................................................... (A),

............................................................................................... (T),

............................................................................................... (C) and

............................................................................................... (G).

2 An enzyme molecule attaches to each of the two separated parental strands.

The two enzyme molecules move in opposite directions, each catalysing the
formation of a new strand of DNA. This enzyme is known as

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

3 DNA ................................................................................................ ,
the monomers of DNA, are activated with two additional phosphates and are
free in the nucleus for the synthesis of the new strands.

4 The bases of the DNA monomers form hydrogen bonds with the bases on
each separated parental strand of DNA, according to the rules of

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

5 One DNA strand is synthesised continuously and the other is synthesised

in sections known as Okazaki fragments. The fragments are joined by an

enzyme, .............................................................................................. , which

catalyses the formation of phosphodiester bonds.

6 The result of replication is two DNA molecules, each one containing an

original parental strand and a newly synthesised strand. This type of
replication is described as

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

Fig. 6.1
[6]

(b) Fig. 6.2 is a photomicrograph of root tip cells at different stages in the cell cycle. A cell in interphase
is labelled.

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

cell in interphase

K .......................................

L .......................................

Fig. 6.2

(i) Name the stage of mitosis shown in each of cells J, K and L in Fig. 6.2.
Write your answer in the space next to each letter on Fig. 6.2. [3]
(ii) Explain how it is possible to deduce that the labelled cell in interphase shown in Fig. 6.2
is in late, rather than early, interphase.

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

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

(iii) Describe the stage of mitosis shown in cell J.

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

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

[Total: 12]

BLANK PAGE

To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.

Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

Cambridge International Examinations
Cambridge International Advanced Subsidiary and Advanced Level
* 1 9 4 3 2 5 5 5 2 1 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions May/June 2018
1 hour 15 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.

READ THESE INSTRUCTIONS FIRST

Answer all questions.

Electronic calculators may be used.

You may lose marks if you do not show your working or if you do not use appropriate units.

At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.

This document consists of 14 printed pages and 2 blank pages.

Answer all questions.

1 Fig. 1.1 is a drawing of a photomicrograph of a spongy mesophyll cell from a leaf.

X Y

Fig. 1.1

(a) On Fig. 1.1, add a label line and the correct letter for each of the three cell structures listed.

• nucleolus = N
• tonoplast = T
• chloroplast = C
[3]

(b) The drawing in Fig. 1.1 is 2000 times larger than the actual size of the cell.

Describe the steps you would follow to determine the actual diameter of the cell in
micrometres (µm), at X—Y.

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

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

(c) The drawing in Fig. 1.1 was made using the high power objective lens of a light microscope.
Some of the structures in Fig. 1.1 confirm that the cell is eukaryotic.

An electron micrograph of the same cell would reveal additional cell structures that are found
in eukaryotes and not in prokaryotes.

List two examples of these additional cell structures.

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

2 ................................................................................................................................................
[2]
© UCLES 2018 9700/22/M/J/18
3

(d) Some of the water that moves out of the xylem within the leaves takes an apoplastic pathway
to the spongy mesophyll cells. There is a film of water on the external surfaces of these cells.
This allows the intercellular air spaces to become saturated with water vapour.

(i) State, in terms of water movement from the xylem to the spongy mesophyll cells in the
leaf, what is meant by the apoplastic pathway.

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

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

(ii) Outline the properties of water that contribute to the apoplastic movement of water to the
spongy mesophyll cells and to the movement of water into the intercellular air spaces.

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

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

(iii) Describe what happens to the water vapour in the intercellular air spaces during the day
and explain why this happens.

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

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

[Total: 15]

2 In 1953, James Watson and Francis Crick published details about the structure of DNA. They
used experimental results from other scientists to help them work out the structure and then built
a model of a section of a DNA molecule, using pieces of wire and metal, with clamp stands to hold
the model in place. This is shown in Fig. 2.1.

Fig. 2.1

(a) Watson and Crick used results from work carried out by Erwin Chargaff. He found that the
proportions of the bases A, T, C and G were different in different species, but within each
species:

• the proportion of A was equal to the proportion of T

• the proportion of G was equal to the proportion of C.

(i) Name the bases A, T, G and C.

A ........................................................................................................................................

T ........................................................................................................................................

G .......................................................................................................................................

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

(ii) Suggest and explain how Chargaff’s findings helped Watson and Crick work out the
structure of DNA.

...........................................................................................................................................

.......................................................................................................................................[3]

(b) Phoebus Levene isolated the nucleotides of DNA and identified the carbohydrate component
of each nucleotide.

State the name of this carbohydrate component.

...............................................................................................................................................[1]

(c) Before the discovery of the structure of DNA as the molecule of inheritance, scientists thought
that proteins were most likely to be the molecules that carried information.

Suggest how the structure of proteins made scientists think that these were the molecules
that carried information.

...................................................................................................................................................

...............................................................................................................................................[2]

[Total: 8]

3 Bacteria may be classified according to differences in cell wall structure. The differences are
shown by using the Gram stain.

• A Gram-positive bacterium has a cell wall mainly composed of a thick layer of peptidoglycan
(murein).
• A Gram-negative bacterium has a more complex cell wall. This wall is composed of a much
thinner layer of peptidoglycan and an outer layer known as the outer membrane.

Escherichia coli is a Gram-negative bacterium.

Fig. 3.1 is a diagram through the cell surface membrane and the cell wall of E. coli.

external environment
lipopolysaccharide

O antigen
(O polysaccharide)

outer
membrane
core polysaccharide
cell wall

lipid A
porin

peptidoglycan periplasm
(watery fluid
containing proteins)

cell surface
membrane

cytoplasm

Fig. 3.1

(a) The antibiotic penicillin kills bacteria by causing them to lyse (burst). It is more effective in
treating diseases caused by Gram-positive bacteria than diseases caused by Gram-negative
bacteria.

Outline how penicillin acts on bacteria and use Fig. 3.1 to suggest why penicillin has little or
no effect at treating diseases caused by Gram-negative bacteria, such as some strains of
E. coli.

...................................................................................................................................................

...............................................................................................................................................[3]

(b) The outer membrane contains transport proteins called OmpF porins. These porins allow the
passive movement of water, ions and small, polar molecules across the outer membrane.
Each OmpF porin is formed from three identical polypeptides.

(i) Explain what is meant by the term passive.

.......................................................................................................................................[1]

(ii) Suggest and explain the features of an OmpF porin as a membrane transport protein.

...........................................................................................................................................

.......................................................................................................................................[4]

(iii) E. coli can regulate the number of OmpF porins in the outer membrane to adapt to
changing conditions. One control mechanism used by E. coli involves the production of a
small mRNA molecule known as micF.

MicF binds to the part of the mRNA molecule containing the START codon for the OmpF
polypeptide.

Suggest and explain how the presence of micF prevents production of OmpF porins.

...........................................................................................................................................

.......................................................................................................................................[2]

(c) Fig. 3.1 shows that the outer membrane of the cell wall of E. coli contains lipopolysaccharides.
These are not present in the cell surface membrane. Each lipopolysaccharide (LPS) consists
of a lipid and a polysaccharide portion.

The O antigen is the outer part of the polysaccharide portion of the LPS. It faces the aqueous
external environment.

(i) Define the term polysaccharide.

...........................................................................................................................................

.......................................................................................................................................[2]

(ii) Some strains of E. coli are pathogenic. Different pathogenic strains have different
O antigens.

Suggest and explain why infection with one pathogenic strain of E. coli does not provide
immunity to a different pathogenic strain.

...........................................................................................................................................

.......................................................................................................................................[3]

[Total: 15]

4 Fig. 4.1 is a photomicrograph showing some cells in interphase and some cells in stages of mitosis.

Fig. 4.1

(a) Choose from the cells labelled 1 to 5 in Fig. 4.1 to identify the cell in which:

• the nuclear envelope is reassembling ..............................

• the spindle begins to form ..............................

• there is a high rate of transcription and translation ..............................

[3]

(b) Cell 2 is in a stage of mitosis that occurs before the stage of mitosis shown in cell 1.

Outline the changes that would occur from the stage of mitosis shown in cell 2 to the stage
shown in cell 1.

...................................................................................................................................................

...............................................................................................................................................[2]

...................................................................................................................................................

...............................................................................................................................................[1]

5 When tobacco smoke is inhaled, chemicals such as nicotine and carbon monoxide enter the
circulatory system through the gas exchange system. Tar builds up on the lining of the gas
exchange system.

Many people decide to give up smoking tobacco in order to improve their health.

(a) Some of the structures in the human gas exchange system through which tobacco smoke
passes are shown in Fig. 5.1.

Fig. 5.1

Describe the gross structure of the human gas exchange system.

...................................................................................................................................................

...............................................................................................................................................[3]

(b) Soon after a person stops smoking, the short term effects of nicotine are reversed.

State the changes that will occur in the cardiovascular system as a result of reduced nicotine
levels.

...................................................................................................................................................

...............................................................................................................................................[2]

Curve A shows measurements obtained from a person who is a heavy smoker.

Curve B shows measurements obtained several weeks after the same person stopped
smoking.

100 B

80 A

percentage 60
saturation of
haemoglobin 40

0
0 2 4 6 8 10 12 14
partial pressure of oxygen / kPa

Fig. 5.2

With reference to Fig. 5.2, describe and explain how the results show some of the health
benefits of stopping smoking.

...................................................................................................................................................

...............................................................................................................................................[4]

(d) A person who gives up smoking decreases their risk of developing lung cancer, a
non-infectious disease.

Explain why lung cancer is described as a non-infectious disease.

...................................................................................................................................................

...............................................................................................................................................[2]

[Total: 11]

6 Enzyme inhibitors and monoclonal antibodies can be used in the treatment of disease.

(a) Mevinolin is an enzyme inhibitor that can be prescribed as a drug to reduce the concentration
of cholesterol in blood plasma.

High concentrations of cholesterol in the blood have been linked to an increased risk of
cardiovascular disease.

Mevinolin acts as a competitive inhibitor of the enzyme HMG CoA reductase. This enzyme
catalyses one of the first steps in the synthesis of cholesterol, as shown in Fig. 6.1.

HMG CoA reductase

HMG CoA mevalonic acid

Fig. 6.1

Explain how mevinolin inhibits the enzyme HMG CoA reductase.

...................................................................................................................................................

...............................................................................................................................................[3]

(b) Outline the use of monoclonal antibodies in the treatment of disease.

...................................................................................................................................................

...............................................................................................................................................[2]

[Total: 5]

BLANK PAGE

Cambridge International Examinations
Cambridge International Advanced Subsidiary and Advanced Level
* 6 1 7 0 8 9 7 5 8 7 *

BIOLOGY 9700/22
Paper 2 AS Level Structured Questions October/November 2018
1 hour 15 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.

READ THESE INSTRUCTIONS FIRST

Answer all questions.

Electronic calculators may be used.

You may lose marks if you do not show your working or if you do not use appropriate units.

At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.

This document consists of 16 printed pages.

Answer all questions.

1 Fig. 1.1A is a photomicrograph of healthy lung tissue.

Fig. 1.1B is a photomicrograph of lung tissue from a person with emphysema, a chronic obstructive
pulmonary disease (COPD). The images are both at magnification × 40.

X
Y H

alveolus

A B

Fig. 1.1

(a) Name the structure labelled H in Fig. 1.1A.

.............................................................................................................................................. [1]

(b) Calculate the actual diameter of the alveolus at X–Y.

Write down the formula and use it to make your calculation.

Give your answer to the nearest whole micrometre (µm).

formula

actual size .................................................... µm [2]

(c) Gas exchange in the lungs occurs in the alveoli.

Describe the process of gas exchange in healthy lungs and suggest how this compares with
gas exchange in the diseased lung shown in Fig. 1.1B.

...................................................................................................................................................

.............................................................................................................................................. [4]

[Total: 7]

2 Woolly foxglove, Digitalis lanata, shown in Fig. 2.1A, and common oleander, Nerium oleander,
shown in Fig. 2.1B, are plants grown for the attractive flowers that they produce.

Both plants are poisonous, as their leaves produce toxic organic compounds known as cardiac
glycosides. Cardiac glycosides have a powerful effect on the action of cardiac muscle.

A B

Fig. 2.1

(a) N. oleander is able to grow in very dry conditions. The leaves have adaptations to reduce
water loss by transpiration.

State the term used to describe a plant, such as N. oleander, that has adaptations to allow it
to grow in conditions where water is in short supply.

.............................................................................................................................................. [1]

(b) Aphids are small insects that feed on plant fluids using piercing and sucking mouthparts.
When aphids feed on the sap present in vascular tissue of leaves and stems, a sugary liquid
called honeydew is passed out of the gut. The honeydew can be analysed to find out what is
present in the sap.

(i) State the name of the vascular tissue from which the aphids feed.

...................................................................................................................................... [1]

(ii) An investigation found that aphids feeding on D. lanata produced honeydew containing
cardiac glycosides.

Suggest why cardiac glycosides were present in the sap from the vascular tissue.

...........................................................................................................................................

...................................................................................................................................... [2]

Cardiac glycosides have an effect on the movement of ions into and out of cardiac muscle cells.
The outcome is an increased ability for the cells to contract.

(c) Investigations into the action of the cardiac glycoside oleandrin, extracted from N. oleander,
have shown that it acts to prevent the correct functioning of Na/K‑ATPase, a membrane
transport protein.

Na/K‑ATPase has a role as an enzyme and as a transport molecule.

• ATPase is an enzyme that catalyses the hydrolysis of ATP to ADP and inorganic
phosphate.
• Energy released from this hydrolysis is used to transport sodium ions (Na+) out of
cardiac muscle cells and potassium ions (K+) into the cells.

(i) Explain what is meant by the hydrolysis of ATP.

...........................................................................................................................................

...................................................................................................................................... [2]

(ii) Name the type of transport mechanism involved in the transport of Na+ and K+ across
the cell surface membrane of cardiac muscle cells.

...................................................................................................................................... [1]

(iii) Oleandrin is a non‑competitive reversible inhibitor of ATPase.

Describe the mode of action of oleandrin and explain how this will affect ion movement
through Na/K‑ATPase transport proteins of the cell surface membranes of cardiac
muscle cells.

...........................................................................................................................................

...................................................................................................................................... [4]

(d) Digoxin, a cardiac glycoside extracted from D. lanata leaves, can be purified and used as a
drug to treat some heart disorders.

Examples of these heart disorders are:

• atrial fibrillation, where the normal rhythmic cardiac cycle is disrupted
• heart failure, where cardiac muscle is contracting weakly.

(i) Describe the sequence of events occurring in the left side of the heart during one normal
cardiac cycle. Include reference to blood pressure changes.

The first event in the sequence is described for you.

The left atrium fills with blood during relaxation of the left atrium and left ventricle.
...........................................................................................................................................

...........................................................................................................................................

...................................................................................................................................... [4]

(ii) Suggest how the health of a person with heart failure can be improved by treatment with
the drug digoxin.

...........................................................................................................................................

...................................................................................................................................... [3]

[Total: 18]

3 The response of the human body to tissue damage depends on the types of tissues involved.
Epithelial tissue, liver tissue and cardiac muscle tissue each respond differently to damage.

• Epithelial tissue of the gas exchange system contains stem cells.

• Liver tissue contains cells in a non‑dividing state that can enter a cell cycle when
stimulated.
• Cardiac muscle tissue contains cells that cannot divide at all. Damage is permanent and
is associated with scar tissue formation.

(a) Explain the importance of mitosis in the repair of damaged tissue.

...................................................................................................................................................

.............................................................................................................................................. [2]

(b) Explain why stem cells are important in tissue repair.

...................................................................................................................................................

.............................................................................................................................................. [2]

(c) Following liver tissue damage, chemicals are produced and released into the circulation.
These chemicals are able to stimulate the liver cells to help tissue repair.

Explain how this is an example of cell signalling.

...................................................................................................................................................

.............................................................................................................................................. [3]

[Total: 7]

4 Viruses share common structural features. Some viruses, such as human immunodeficiency
virus (HIV), also have an outer envelope as part of their structure.

(a) Outline the key structural features of viruses.

...................................................................................................................................................

.............................................................................................................................................. [3]

HIV can remain in a dormant state within infected immune system cells for many years. A person
diagnosed as HIV‑positive (HIV+) has the virus but does not have symptoms of HIV/AIDS.

The chances of an HIV+ person developing HIV/AIDS can be greatly reduced with a drug treatment
programme known as anti‑retroviral therapy (ART).

(b) In 2010, the World Health Organization (WHO) published recommendations for the treatment
of pregnant women living with HIV. This includes both HIV+ women and women who have
developed HIV/AIDS.

The publication recommended that all pregnant and breastfeeding women living with HIV
should be provided with ART.

Fig. 4.1 shows the number of pregnant women living with HIV, and the number of these
receiving ART, between 2005 and 2013, in low and middle income countries.

Key
total number of pregnant women living with HIV
number of pregnant women living with HIV receiving ART
2 000 000

1 800 000

1 600 000

1 400 000

1 200 000
number of
pregnant 1 000 000
women
800 000

600 000

400 000

200 000

0
2005 2006 2007 2008 2009 2010 2011 2012 2013
year

Fig. 4.1

(i) From the data in Fig. 4.1, it can be calculated that 13% of pregnant women living with
HIV received ART in 2005.

Calculate the percentage of pregnant women living with HIV that received ART in 2013.

answer = .......................... % [1]

(ii) Describe the trends shown in Fig. 4.1.

...........................................................................................................................................

...................................................................................................................................... [3]

(iii) Suggest and explain the global importance of providing ART to all pregnant and
breastfeeding women living with HIV.

...........................................................................................................................................

...................................................................................................................................... [3]

Question 4 continues on page 12

(c) In a person who has been infected with HIV‑1, the most common strain of HIV, a sample of
blood can be tested for the presence of the virus.
One test that can only be used in the early stages of infection involves a monoclonal antibody
specific for p24, a structural protein present in the virus.

Fig. 4.2 is a flow chart outlining the steps in the production of anti‑HIV p24 monoclonal
antibody.

inject mouse

step 1

remove cells from mouse obtain mouse myeloma

step 2 spleen cells

fuse cells from spleen with

step 3 myeloma cells

clone fused cells in a

step 4
culture medium

separate cells and culture

step 5
in individual wells

screen cells to identify

step 6
desired cells

culture desired cells on a

step 7
large scale

Fig. 4.2

(i) State what is being injected into the mouse in step 1.

...................................................................................................................................... [1]

(ii) Explain why several weeks, rather than several days, separates step 1 and step 2.

...........................................................................................................................................

...................................................................................................................................... [1]

(iii) State one feature of the myeloma mouse cells, used in step 3, that is essential for this
production process.

...........................................................................................................................................

...................................................................................................................................... [1]

(iv) Name the fused cells formed in step 4.

...................................................................................................................................... [1]

(v) Suggest why step 6 is necessary.

...........................................................................................................................................

...................................................................................................................................... [1]

[Total: 15]

5 DNA and RNA are nucleic acids.

(a) Explain why RNA can be described as a polymer and as a macromolecule.

...................................................................................................................................................

.............................................................................................................................................. [2]

(b) The sugar component of DNA is a reducing sugar.

Outline the test for reducing sugars and describe the observations for a positive result.

...................................................................................................................................................

.............................................................................................................................................. [2]

(c) Nucleotides are structural components of nucleic acids. Each nucleotide consists of a pentose
sugar, a phosphate group and a nitrogenous organic base.

Complete Table 5.1 to compare DNA nucleotides with RNA nucleotides as structural
components of nucleic acids.

Table 5.1

feature DNA nucleotides RNA nucleotides

pentose sugar
component

purine bases

pyrimidine bases

[3]

[Total: 7]

6 As a red blood cell matures, cell organelles are lost from the cell. This provides more space for the
haemoglobin molecules that have been synthesised.

(a) The red blood cell has a short lifespan due to the loss of the nucleus and other organelles.

State one function performed by each of the organelles listed, before they are lost from the
developing red blood cell.

rough endoplasmic reticulum

...................................................................................................................................................

Golgi body

...................................................................................................................................................

centrioles

...................................................................................................................................................
[3]

(b) State the most appropriate term to match each of the descriptions A to C.

A The part of the haem group that binds oxygen in each haemoglobin polypeptide.

...................................................................................................................................................

B The compound formed when carbon dioxide binds to haemoglobin.

...................................................................................................................................................

C The compound formed when hydrogen ions (H+) bind to haemoglobin.

...................................................................................................................................................
[3]

[Total: 6]

To avoid the issue of disclosure of answer‑related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.

AS Level Biology Exam Guide
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