Cambridge A Level Biology 9700 — 2020 May/June Paper 1 · Variant 1

Question 1

1 The photomicrograph shows the ultrastructure of part of a cell. Which statement about the type of cell shown in the photomicrograph is correct? A It is a plant cell because it has both chloroplasts and a nucleus. B It is a plant cell because it has chloroplasts. C It is an animal cell because it has a cell membrane. D It is an animal cell because it has mitochondria.

Accepted Answer

B

Question 2

2 Which structures are found in typical eukaryotic cells? 1 70S ribosomes 2 80S ribosomes 3 linear DNA (chromosomes) 4 circular DNA A 1, 2, 3 and 4 B 1, 2 and 3 only C 1 and 4 only D 2 and 3 only

Accepted Answer

A

Question 3

3 A student examined a slide of human blood with a light microscope and made a careful drawing of the different cell types. The student used an eyepiece graticule so that the relative sizes of the different cell types were drawn accurately. In the drawing: ● red blood cells were 7 mm in diameter ● lymphocytes were 6 mm in diameter ● neutrophils were 14 mm in diameter. What is the linear magnification of the drawing? A ×10 B ×40 C ×100 D ×1000

Accepted Answer

D

Question 4

4 The diagram shows a graduated slide, with divisions of 0.1 mm viewed using an eyepiece graticule. 0 10 20 30 40 50 60 70 80 90 100 Pollen grains were grown in a sugar solution and viewed using the eyepiece graticule. Diagram 1 shows the pollen grains at the start. Diagram 2 shows the pollen grains after four hours. diagram 1 diagram 2 pollen tube 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 at start after 4 hours What is the growth rate of the pollen tubes? A 5 µmh–1 B 10 µmh–1 C 5 mmh–1 D 10 mmh–1

Accepted Answer

A

Question 5

5 The table shows a comparison between two features of a typical eukaryotic cell and a typical

prokaryotic cell.

Which row shows the correct comparison between these cells?

presence of centromeres presence of telomeres
eukaryotic | prokaryotic | eukaryotic | prokaryotic
cell cell cell cell
v v x x

00 WwW >

v x v x
x v x v
x x v v

key
v¥ = present

X = not present

Accepted Answer

B

Question 6

6 The flow diagram shows the results of a number of tests on a solution of biochemicals. solution of biochemicals Benedict’s test non-reducing iodine test biuret test blue sugar test blue-black purple yellow Which substances are present in the solution? A amylose, amylopectin and lipid B glucose, starch and catalase C sucrose, amylase and triglyceride D sucrose, starch and catalase

Accepted Answer

D

Question 7

7 Maltose and sucrose are disaccharides. Maltose is formed from two molecules of glucose, whilst sucrose is formed from fructose and glucose. Which row shows the molecular formulae of the two disaccharides? maltose sucrose A C12H22O11 C12H22O11 B C12H22O11 C12H24O12 C C12H24O12 C12H22O11 D C12H24O12 C12H24O12

Accepted Answer

A

Question 8

8 The diagrams show short sections of some common polysaccharides and modified polysaccharides. CH2OH H NHCOCH3 CH2OH H OH O O H O H H O H H OH H H OH H O OH H H O O OH H H O H H H H O O H NHCOCH3 CH2OH H OH CH2OH 1 2 CH2OH CH2OH O O H H H H H H O OH H O OH H O H OH H OH 3 The polysaccharides can be described as: ● F is composed of β-glucose monomers with 1,4 glycosidic bonds ● G is composed of α-glucose monomers with 1,4 glycosidic bonds ● H is composed of N-acetylglucosamine monomers with β-1,4 glycosidic bonds. Which row correctly matches the numbered diagrams to the descriptions of the polysaccharides? polysaccharide polysaccharide polysaccharide F G H A 2 1 3 B 2 3 1 C 3 1 2 D 3 2 1

Accepted Answer

B

Question 9

9 Which molecules contain at least two double bonds? 1 unsaturated fatty acid 2 collagen 3 haemoglobin A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Accepted Answer

A

Question 10

10 The diagram shows a protein molecule. globular head key long polypeptide short polypeptide Two long polypeptides each form α-helices for much of their length and these twist together into a fibre. At one end, each of these polypeptides coils into a globular head. Two short polypeptides bind to each globular head. What describes the protein structure of this molecule? A quaternary structure because each molecule consists of six polypeptides B secondary structure because the long polypeptides form α-helices C tertiary structure because the α-helices form a fibre D tertiary structure because the heads form globular proteins

Accepted Answer

A

Question 11

11 Which types of bond will keep a folded protein in its precise shape for the longest time as the temperature rises? A disulfide B hydrogen C hydrophobic interactions D ionic

Accepted Answer

A

Question 12

12 Protease enzymes are found in many locations inside and outside the cells. Four of these locations are listed. 1 lysosomes 2 lumen of the stomach 3 at a telophase spindle 4 mucus in the trachea Which of these locations are sites of intracellular hydrolysis? A 1, 2, 3 and 4 B 1, 2 and 4 only C 1 and 3 only D 2 and 4 only

Accepted Answer

C

Question 13

13 An enzyme is modified for industrial use. It has a lower Michaelis-Menten constant (Km) than the unmodified enzyme. What is true of the modified enzyme? A It is more specific. B It has a higher affinity for its substrate. C It has a lower maximum rate of reaction (Vmax). D It needs more substrate to become saturated.

Accepted Answer

B

Question 14

14 A decrease in some factors will increase the fluidity of the cell surface membrane. Which pair of factors, when decreased, will increase the fluidity of the cell surface membrane? a decrease in A • distance between phospholipid molecules • proportion of short fatty acid chains B • distance between phospholipid molecules • temperature C • proportion of phospholipids with saturated fatty acid chains • proportion of long fatty acid chains D • proportion of phospholipids with unsaturated fatty acid chains • temperature

Accepted Answer

C

Question 15

15 The diagram shows a cell surface membrane. 2 3 1 4 Which statements about the labelled molecules in the membrane are correct? ● 1 is involved in the diffusion of ions. ● 2 is involved in facilitated diffusion. ● 3 is involved in the recognition of antigens. ● 4 is involved in membrane fluidity. A 1, 2 and 3 B 1 and 3 only C 1 and 4 D 2 and 4 only

Accepted Answer

D

Question 16

16 Equal sized potato pieces were placed into test-tubes containing equal volumes of different concentrations of sucrose solution and left for 30 minutes. All other variables were controlled. After 30 minutes, the potato piece in one of the concentrations of sucrose solution had not changed in size. What can be concluded from this result? 1 There is no net movement of water into or out of the potato. 2 The water potential of the potato is the same as the water potential of the sucrose solution. 3 The concentration of sucrose in the potato is the same as the concentration of the sucrose solution. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 only

Accepted Answer

B

Question 17

17 Which feature of stem cells enables them to replace cells in tissues such as the skin? A They are undifferentiated cells that are present at birth. B They differentiate to form skin cells. C They divide by mitosis to supply some cells that can differentiate. D They have the full number of chromosomes.

Accepted Answer

C

Question 18

18 During prophase, a scientist stains the chromosomes of a diploid animal cell with a fluorescent dye to stain telomeres. This cell has 32 chromosomes. How many telomeres will the scientist observe? A 32 B 64 C 96 D 128

Accepted Answer

D

Question 19

19 The diagram shows the cell cycle. During which phase do chromosomes condense and become visible? cytokinesis D C A B

Accepted Answer

D

Question 20

20 What is correct for thymine?

has a single ring

is a pyrimidine

joins its
complementary base

structure with 3 hydrogen bonds
A v v v
B "4 v x
c Y x x
D x x v

key
Y = correct
X = incorrect

Accepted Answer

B

Question 21

21 A short piece of DNA 15 base pairs long was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown below. number of nucleotide bases A C G T strand 1 6 3 strand 2 4 How many nucleotides containing guanine were present in strand 1? A 2 B 3 C 4 D 6

Accepted Answer

A

Question 22

22 Scientists grew bacteria in a medium containing heavy nitrogen, 15N, as the only source of nitrogen. After many generations, all of the bacterial DNA contained heavy nitrogen. These bacteria were then moved from the heavy nitrogen medium into a medium with only light nitrogen, 14N. Some bacteria were collected from each of the next three generations and their DNA was analysed. Hybrid DNA contains both heavy and light nitrogen. Which row shows the correct DNA of the first and third generations? DNA of first generation DNA of third generation A all hybrid half hybrid, half light B all hybrid one quarter hybrid, three quarters light C half hybrid, half heavy half hybrid, one quarter heavy, one quarter light D half hybrid, half light one quarter hybrid, three quarters light

Accepted Answer

B

Question 23

23 A population of bacteria is exposed to the antibiotic penicillin. Most of the bacteria die. However, some bacteria in the population have an allele coding for an enzyme that breaks down penicillin. These bacteria are able to survive. Which could explain how these bacterial cells acquired this allele? 1 An error during DNA replication. 2 An error during transcription. 3 An error during translation. A 1, 2 and 3 B 1 and 3 only C 1 only D 2 and 3 only

Accepted Answer

C

Question 24

24 A dicotyledonous leaf has a palisade mesophyll layer that is approximately twice as thick as the spongy mesophyll layer. Which plan diagram is correct? A B upper surface upper surface of leaf of leaf xylem phloem phloem xylem C D upper surface upper surface of leaf of leaf xylem phloem phloem xylem

Accepted Answer

C

Question 25

25 A number of processes contribute to maintaining a water potential gradient in plants allowing water to reach the highest parts of a plant. Which processes are responsible for maintaining this water potential gradient? 1 capillarity 2 osmosis 3 transpiration A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Accepted Answer

A

Question 26

26 What is a correct statement about the movement of substances absorbed by roots? A Ions have to pass through cell walls to cross the endodermis. B Ions move through the symplastic pathway only until they reach the Casparian strip. C Soil water has a more negative water potential than the xylem sap. D Water passes through the symplastic pathway along a water potential gradient.

Accepted Answer

D

Question 27

27 Which arrangement of four molecules of water shows how water may cohere when moving up a xylem vessel? A B key oxygen atom hydrogen atom hydrogen bond C D

Accepted Answer

B

Question 28

28 Which statement about sucrose loading into companion cells and then into the phloem sieve tube element is not correct? A Hydrogen ions and sucrose molecules move into the companion cells using a carrier protein. B Hydrogen ions are pumped out of the companion cells by active transport. C Sucrose molecules are carried into the companion cells down the concentration gradient for sucrose. D Sucrose molecules move from a companion cell into the sieve tubes of the phloem through plasmodesmata.

Accepted Answer

C

Question 29

29 What explains why the left and right sides of the heart contract simultaneously? A Both atria have a sinoatrial node. B Both sides of the heart are supplied by the same coronary artery. C Purkyne tissue links the two sides of the heart. D There is no barrier to electrical excitation between two sides of the heart.

Accepted Answer

D

Question 30

30 The statements list some of the events in the cardiac cycle. They are not in the correct order. 1 The impulse travels through Purkyne tissue. 2 A wave of excitation sweeps across the atria. 3 The atrioventricular node delays the impulse for a fraction of a second. 4 The sinoatrial node contracts. 5 The wave of excitation sweeps upwards from the base of the ventricles. 6 The ventricles contract. 7 The atria contract. Which statement describes the third of these events to occur in the cardiac cycle? A 1 B 3 C 4 D 7

Accepted Answer

D

Question 31

31 The diagram shows pressure changes in different parts of the heart during one cardiac cycle. During which period are the semilunar valves open and the atrioventricular valves closed? A B C D pressure key aortic pressure ventricle pressure atrial pressure 0 time

Accepted Answer

C

Question 32

32 Which diagram shows the events that occur during transport of carbon dioxide by the blood? A B CO2 CO2 tissue fluid tissue fluid plasma plasma CO2 + water CO2 + CO2 + carbonic carbamino- haemoglobin water anhydrase haemoglobin carbonic H+ + HCO3 – H2CO3 CO2 + anhydrase haemoglobin H2CO3 carbamino- haemoglobin H+ + HCO3 – red blood red blood cell cell C D CO2 CO2 tissue fluid tissue fluid plasma plasma CO2 + CO2 + CO2 + CO2 + water haemoglobin H2CO3 haemoglobin water carbonic H+ + anhydrase carbonic carbamino- HCO3 – H+ + HCO3 – H2CO3 carbamino- haemoglobin anhydrase haemoglobin red blood red blood cell cell

Accepted Answer

C

Question 33

33 Which structures are found in bronchi? smooth muscle A C B goblet cartilage D cells

Accepted Answer

B

Question 34

34 Which tissue in the respiratory system is correctly linked to its function? tissue function A cartilage stretch and recoil to force air out B ciliated epithelium gives protection from suspended particles in the air C elastic fibres contract and relax to adjust diameter of bronchioles D smooth muscle keeps trachea and bronchi open

Accepted Answer

B

Question 35

35 Chronic obstructive pulmonary disease (COPD) includes emphysema. Which effects does emphysema have on gaseous exchange? 1 surface area to volume ratio of lungs decreases 2 distance of the diffusion pathway decreases 3 volume of oxygen diffused per unit time decreases A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Accepted Answer

C

Question 36

36 The diagram shows some of the pathogens that cause disease in humans and some of the ways they are transmitted. X 1 2 contaminated bacterium protoctist water pathogen method of transmission 3 Z Y virus using a coughs and vector sneezes Which row matches the correct number for the pathogen with the correct letter for their mode of transmission for cholera and measles? cholera measles A 1 and X 3 and Y B 1 and Y 3 and Y C 2 and X 2 and Z D 3 and Z 1 and X

Accepted Answer

A

Question 37

37 Which factors would increase the global distribution of malaria? 1 a fall in annual rainfall 2 an increase in the use of antibiotics 3 a rise in global air temperatures 4 increasing irrigation of land for farming A 1, 2 and 3 B 1 and 2 only C 2, 3 and 4 D 3 and 4 only

Accepted Answer

D

Question 38

38 The antibiotic teixobactin was discovered in January 2015. Teixobactin kills some bacteria such as Staphylococcus and Mycobacterium. Most antibiotics work by binding to proteins. Teixobactin binds to lipids that are used in the synthesis of bacterial cell walls. This means that it is unlikely that bacteria will quickly develop resistance to teixobactin. Which statements explain why bacteria are unlikely to quickly develop resistance to teixobactin? 1 A mutation in the gene coding for a protein allows selection for resistance. 2 Teixobactin binds to a lipid rather than to a protein. 3 The structure of a lipid is not encoded by DNA. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Accepted Answer

D

Question 39

39 Which row correctly describes the type of immunity gained from being injected with an antitoxin?

active artificial passive natural

v Jv x x key
Y =correct

X =not correct

0 0O WwW D>

v x
x v
x x

<< x
KM

Accepted Answer

C

Question 40

40 Where are antibodies found during an immune response?

on surface of in blood
pathogen plasma
Jv v key

JY = antibodies found

0 Oo WwW >

J x
x v X = antibodies not found
x x

Accepted Answer

A

Question paper20 pages

Mark scheme3 pages

Questions as text

Q1 · The photomicrograph shows the ultrastructure of part of a cell

Q2 · Which structures are found in typical eukaryotic cells?

Q3 · A student examined a slide of human blood with a light microscope and made a careful…

Q4 · The diagram shows a graduated slide, with divisions of 0.1 mm viewed using an eyepiece…

Q5 · The table shows a comparison between two features of a typical eukaryotic cell and a…

Q6 · The flow diagram shows the results of a number of tests on a solution of biochemicals

Q7 · Maltose and sucrose are disaccharides

Q8 · The diagrams show short sections of some common polysaccharides and modified…

Q9 · Which molecules contain at least two double bonds?

Q10 · The diagram shows a protein molecule

Q11 · Which types of bond will keep a folded protein in its precise shape for the longest time…

Q12 · Protease enzymes are found in many locations inside and outside the cells

Q13 · An enzyme is modified for industrial use

Q14 · A decrease in some factors will increase the fluidity of the cell surface membrane

Q15 · The diagram shows a cell surface membrane

Q16 · Equal sized potato pieces were placed into test-tubes containing equal volumes of…

Q17 · Which feature of stem cells enables them to replace cells in tissues such as the skin?

Q18 · During prophase, a scientist stains the chromosomes of a diploid animal cell with a…

Q19 · The diagram shows the cell cycle

Q20 · What is correct for thymine?

Q21 · A short piece of DNA 15 base pairs long was analysed to find the number of nucleotide…

Q22 · Scientists grew bacteria in a medium containing heavy nitrogen, 15N, as the only source…

Q23 · A population of bacteria is exposed to the antibiotic penicillin

Q24 · A dicotyledonous leaf has a palisade mesophyll layer that is approximately twice as thick…

Q25 · A number of processes contribute to maintaining a water potential gradient in plants…

Q26 · What is a correct statement about the movement of substances absorbed by roots?

Q27 · Which arrangement of four molecules of water shows how water may cohere when moving up a…

Q28 · Which statement about sucrose loading into companion cells and then into the phloem sieve…

Q29 · What explains why the left and right sides of the heart contract simultaneously?

Q30 · The statements list some of the events in the cardiac cycle

Q31 · The diagram shows pressure changes in different parts of the heart during one cardiac…

Q32 · Which diagram shows the events that occur during transport of carbon dioxide by the blood?

Q33 · Which structures are found in bronchi?

Q34 · Which tissue in the respiratory system is correctly linked to its function?

Q35 · Chronic obstructive pulmonary disease (COPD) includes emphysema

Q36 · The diagram shows some of the pathogens that cause disease in humans and some of the ways…

Q37 · Which factors would increase the global distribution of malaria?

Q38 · The antibiotic teixobactin was discovered in January 2015

Q39 · Which row correctly describes the type of immunity gained from being injected with an…

Q40 · Where are antibodies found during an immune response?

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