Cambridge A Level Biology 9700 — 2021 May/June Paper 1 · Variant 1

Question 1

1 The diagram shows a mitochondrion drawn from an electron micrograph. Y X The actual length of the mitochondrion, using the line X–Y, is 3000 nm. What is the magnification of the drawing of the mitochondrion? A 100 B 1000 C 10 000 D 100 000

Accepted Answer

C

Question 2

2 A specimen of plant tissue is observed twice with a microscope, firstly using red light with a wavelength of 650 nm and then using green light with a wavelength of 510 nm. What happens to the magnification and resolution when using green light compared to red light? magnification resolution A decreases decreases B increases increases C remains the same decreases D remains the same increases

Accepted Answer

D

Question 3

3 The electron micrograph shows a structure found in the cytoplasm of an animal cell. What is this cell structure? A centriole B lysosome C ribosome D vesicle

Accepted Answer

A

Question 4

4 Which cell structures contain nucleic acid? 1 Golgi body 2 lysosome 3 mitochondria 4 ribosomes A 1, 2 and 3 B 1, 2 and 4 C 1 and 4 only D 3 and 4

Accepted Answer

D

Question 5

5 Which statements about mitochondria, chloroplasts or prokaryotes are correct? 1 Mitochondria and chloroplasts have a fully permeable inner membrane and a partially permeable outer membrane. 2 Prokaryotes and chloroplasts have 70S ribosomes that are the sites for translation and polypeptide synthesis. 3 Prokaryotes and mitochondria have an outer membrane and an inner, folded membrane where ATP synthesis occurs. 4 Prokaryotes and mitochondria have circular DNA where genes coding for information are located. A 1, 2 and 3 B 1, 2 and 4 C 1 and 3 only D 2 and 4 only

Accepted Answer

D

Question 6

6 The very large (1000 nm) Pandora viruses found in Chile and Australia are considered to be viruses because they cannot replicate their own genome and cannot make proteins. They also share essential structural features with other viruses. What are the essential structural features of viruses? 1 non-cellular 2 protein coat 3 both DNA and RNA 4 either DNA or RNA A 1, 2 and 3 B 1, 2 and 4 C 1 and 3 only D 2 and 4 only

Accepted Answer

B

Question 7

7 A sample of food was heated with Benedict’s solution which changed colour to green. A second sample of the same food was boiled with dilute hydrochloric acid and neutralised using sodium hydrogencarbonate. It was then heated with Benedict’s solution which changed colour to red. What did these results show? glucose present A reducing D non-reducing sugar present sugar present C B

Accepted Answer

C

Question 8

8 Which pair of molecules only includes macromolecules that can be found in animal cells? A amylase and amylopectin B collagen and glycogen C deoxyribose and starch D sucrose and haemoglobin

Accepted Answer

B

Question 9

9 Homogalacturonan is a polysaccharide found in plant cell walls. The diagram shows a molecule of the monomer used to form homogalacturonan. CO2H O HO H OH H H OH H OH A student studied the structure of this monomer and compared it with the structure of the monomer used to form cellulose. Which carbon atoms in the monomer in the diagram have hydroxyl groups arranged in different positions to those found in the cellulose monomer? A carbon one and carbon four B carbon one only C carbon three and carbon four D carbon three only

Accepted Answer

A

Question 10

10 Which statement is correct for triglycerides and phospholipids? A A phosphate group is joined to a glycerol molecule. B Hydrocarbon chains may be saturated or unsaturated. C They are polar molecules. D They contain three ester bonds.

Accepted Answer

B

Question 11

11 Which description of collagen is correct? A A collagen molecule consists of three polypeptide chains, each in the shape of a helix. The three chains are wound together into a triple helix called a fibre. B A collagen molecule consists of three polypeptide chains, each of which is an -helix. The three chains are wound tightly together into a triple helix. Many of these triple helices bind together as a fibre. C A collagen molecule consists of three polypeptide chains wound tightly into a triple helix called a fibre. D A collagen molecule consists of three polypeptide chains in which every third amino acid is glycine. The three polypeptides are wound tightly together into a triple helix. Many of these helices form a fibre.

Accepted Answer

D

Question 12

12 In a healthy human, the mean value for the number of haemoglobin molecules in one red blood cell is 260 million. How many -globin chains does one red blood cell contain in a healthy human? A 1.3  108 B 2.6  108 C 5.2  108 D 1.04  109

Accepted Answer

C

Question 13

13 Which statements about a peptide bond are correct? 1 It joins two monomers which are always identical to each other. 2 It contains four different atoms. 3 It can be broken by the addition of water at room temperature. 4 It is important in the primary structure of proteins. A 1, 2 and 3 B 1 and 3 only C 2, 3 and 4 D 2 and 4 only

Accepted Answer

D

Question 14

14 Which graph correctly shows the activation energy of a reaction when an enzyme is added? A B activation activation energy energy no enzyme no enzyme enzyme enzyme energy products energy products reactants reactants progress of reaction progress of reaction C D activation activation energy no enzyme energy no enzyme enzyme enzyme energy reactants energy reactants products products progress of reaction progress of reaction

Accepted Answer

D

Question 15

15 The enzyme lactase is found in the membranes of epithelial cells lining the small intestine. The enzyme is formed by a single polypeptide that folds to give three regions.  an active site with the free amino group outside the cell  a short section inside the membrane  a short section inside the cell What type of amino acid would be found in each of the three regions? inside the inside the outside the cell membrane cell A hydrophilic hydrophobic hydrophilic B hydrophilic hydrophobic hydrophobic C hydrophobic hydrophilic hydrophobic D hydrophobic hydrophobic hydrophilic

Accepted Answer

A

Question 16

16 A student wrote three statements about cell signalling. 1 A signal chemical always has the same shape as a protein receptor on a target cell. 2 An increase in temperature may decrease the effect of cell to cell signalling. 3 A mutation may decrease production of active protein receptors for the cell surface membrane. Which statements are correct? A 1, 2 and 3 B 1 and 3 only C 1 only D 2 and 3 only

Accepted Answer

D

Question 17

17 At which stages of mitosis are chromosomes composed of two chromatids that are held together by a centromere? A anaphase and telophase B anaphase and prophase C metaphase and prophase D metaphase and telophase

Accepted Answer

C

Question 18

18 The jellyfish, Turritopsis dohrnii, is described as being immortal. If T. dohrnii is not eaten by predators or diseased, it seems to be able to live forever. There is no way to determine the biological age of a T. dohrnii individual. Which feature of the cells in T. dohrnii could explain these observations? A very long G phases in the cell cycle B a very short S phase in the cell cycle C an ability to restore telomeres to their original length D fewer chromosomes than other eukaryotic organisms

Accepted Answer

C

Question 19

19 Some chemicals, used to stop tumour growth, work by preventing the DNA double helix from uncoiling and separating. During which stage of the cell cycle would they act? A anaphase B interphase C metaphase D prophase

Accepted Answer

B

Question 20

20 Four nucleotides, A, B, C and D, each consist of three phosphate groups, a nitrogenous base and a pentose sugar. Characteristics of the base and sugar components before they are joined to form each nucleotide are shown in the table. Which nucleotide could pair with an adenine base during DNA replication? ratio of carbon to ring structure of oxygen atoms in nitrogenous base pentose sugar A double 1 : 1 B double 5 : 4 C single 1 : 1 D single 5 : 4

Accepted Answer

D

Question 21

21 The statements describe the process of translation. 1 A peptide bond forms between adjacent amino acids. 2 Hydrogen bonds form between the anticodon and the codon. 3 mRNA binds to the ribosome. 4 tRNA enters the ribosome carrying a specific amino acid. In which order does this process take place? A 3  2  1  4 B 3  4  2  1 C 4  2  1  3 D 4  2  3  1

Accepted Answer

B

Question 22

22 The sequence of amino acids in a section of a polypeptide is: … histidine–proline–aspartic acid–leucine... amino acid possible DNA triplet codes aspartic acid CTA CTG histidine GTA GTG leucine GAT GAC proline GGA GGG What is a correct sequence of mRNA codons for this polypeptide section? A …CAC CCC GAA CUG… B …CAU CCU GAC CUA… C …GTA CCA CTG GAT… D …GUA GGA CUG GAU…

Accepted Answer

B

Question 23

23 What contributes to the upward movement of water in a xylem vessel of a plant? 1 cohesion of water molecules by hydrogen bonding 2 adhesion of water molecules to the cellulose walls of xylem vessels by hydrogen bonding 3 removal of water from xylem vessels in a leaf reduces the hydrostatic pressure in the xylem A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Accepted Answer

A

Question 24

24 The diameter of a tree trunk usually decreases slightly during the day. Which changes in environmental factors during the day could cause the diameter to decrease even more? increased light intensity C A D increased increased wind speed B temperature

Accepted Answer

D

Question 25

25 The diagram shows a transverse section of a stem. Which area is the phloem? A D C B

Accepted Answer

B

Question 26

26 The diagram shows a xerophytic leaf in different conditions, P and Q. Y Y P Q Which statements describe the difference between the cells in layer Y in conditions P and Q? 1 more negative water potential in P than Q 2 more cells plasmolysed in P 3 cells less turgid in Q 4 water potential becomes zero in Q A 1, 2 and 3 B 1 and 2 only C 2 and 4 D 3 and 4

Accepted Answer

B

Question 27

27 Different substances, such as sucrose and amino acids, can move in different directions in the phloem sieve tube elements. Which statement explains this? A Active transport occurs in some phloem sieve tube elements and mass flow occurs in other sieve tube elements. B Both active transport and mass flow occur in each individual phloem sieve tube element. C Mass flow occurs in both directions at the same time in each individual phloem sieve tube element. D Mass flow occurs in different directions in different phloem sieve tube elements at the same time.

Accepted Answer

D

Question 28

28 The statements list some of the events in a cardiac cycle. The statements are not in the correct order. Which statement describes the fourth of these events to occur in the cardiac cycle? 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. A 1 B 3 C 4 D 7

Accepted Answer

B

Question 29

29 Which row correctly identifies components of both lymph and tissue fluid?

~ «QOS

x
v
x

antibodies red white
blood cells ions blood cells
J Jv J

v
x
v

key
¥ = component present

X = component not present

Accepted Answer

B

Question 30

30 Which row is correct for the mean blood pressure in different parts of the human circulatory system? mean blood pressure right artery in vein in capillary atrium arm arm in arm key A + ++++ ++ +++ ++++ highest mean blood pressure B ++ ++++ +++ + +++ C +++ ++ ++++ + ++ D ++++ +++ + ++ + lowest mean blood pressure

Accepted Answer

A

Question 31

31 Which mechanism accounts for the way most of the carbon dioxide is transported in blood? A Carbon dioxide dissolves in plasma and is carried in solution. B Carbon dioxide is converted to carbaminohaemoglobin inside red blood cells. C Carbon dioxide is converted to carboxyhaemoglobin inside red blood cells. D Carbon dioxide is converted to hydrogencarbonate ions inside red blood cells.

Accepted Answer

D

Question 32

32 The graph shows the dissociation curves for haemoglobin at two different partial pressures of carbon dioxide. At which position on the graph, A, B, C, or D, is the concentration of haemoglobinic acid lowest in red blood cells? low carbon dioxide partial pressure C D percentage saturation of haemoglobin with oxygen high carbon dioxide partial pressure A B partial pressure of oxygen / kPa

Accepted Answer

C

Question 33

33 The table shows the partial pressure of carbon dioxide and oxygen in two blood vessels. partial pressure of partial pressure of gas in pulmonary gas in pulmonary artery / kPa vein / kPa carbon dioxide 6 5 oxygen 5 15 What explains the difference in the partial pressures of oxygen in the pulmonary artery and pulmonary vein? A Oxygen diffuses from the alveoli into the blood in the capillaries. B Carbon dioxide diffuses into the alveoli from the blood in the capillaries. C Oxygen diffuses from the body cells into the blood in the capillaries. D Carbon dioxide diffuses into the body cells from the blood in the capillaries.

Accepted Answer

A

Question 34

34 Which graph shows the effect of carbon monoxide on the percentage saturation of haemoglobin with oxygen? A B percentage percentage saturation of saturation of haemoglobin haemoglobin with oxygen with oxygen key = without carbon partial pressure partial pressure monoxide of oxygen of oxygen = with carbon monoxide C D percentage percentage saturation of saturation of haemoglobin haemoglobin with oxygen with oxygen partial pressure partial pressure of oxygen of oxygen

Accepted Answer

A

Question 35

35 Which row shows the correct methods of transmission of the named pathogens? method of transmission airborne droplets insect vector water A Morbillivirus Mycobacterium Vibrio B Mycobacterium Plasmodium Vibrio C Plasmodium Vibrio Morbillivirus D Vibrio Plasmodium Mycobacterium

Accepted Answer

B

Question 36

36 Which disease is caused by a eukaryote? A cholera B malaria C measles D smallpox

Accepted Answer

B

Question 37

37 What is the initial mechanism by which bacteria become resistant to antibiotics? A genetic mutation B overuse of antibiotics C natural selection D patients not finishing a course of antibiotics

Accepted Answer

A

Question 38

38 What are functions of T-lymphocytes? 1 production of cytokines 2 production of toxins 3 recognition of an antigen bound to an antigen-presenting cell A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Accepted Answer

A

Question 39

39 What is correct about the role of memory cells in long-term immunity? 1 They divide to form plasma cells and memory cells when the pathogen enters the body a second time. 2 They produce a fast response so that the person infected with the pathogen does not become ill again. 3 They produce more antibodies than were produced during the primary immune response. 4 They remain in the blood and lymphatic system after the pathogen has been destroyed. A 1, 2 and 3 B 1, 2 and 4 C 1 and 3 only D 2 and 4 only

Accepted Answer

B

Question 40

40 Which events result in a person developing actively acquired immunity? 1 becoming infected by TB bacteria 2 drinking breast milk 3 receiving an injection of antigens 4 receiving an injection of antibodies A 1, 2 and 3 B 1, 3 and 4 C 1 and 3 only D 2 and 4

Accepted Answer

C

Question paper16 pages

Mark scheme3 pages

Questions as text

Q1 · The diagram shows a mitochondrion drawn from an electron micrograph

Q2 · A specimen of plant tissue is observed twice with a microscope, firstly using red light…

Q3 · The electron micrograph shows a structure found in the cytoplasm of an animal cell

Q4 · Which cell structures contain nucleic acid?

Q5 · Which statements about mitochondria, chloroplasts or prokaryotes are correct?

Q6 · The very large (1000 nm) Pandora viruses found in Chile and Australia are considered to…

Q7 · A sample of food was heated with Benedict’s solution which changed colour to green

Q8 · Which pair of molecules only includes macromolecules that can be found in animal cells?

Q9 · Homogalacturonan is a polysaccharide found in plant cell walls

Q10 · Which statement is correct for triglycerides and phospholipids?

Q11 · Which description of collagen is correct?

Q12 · In a healthy human, the mean value for the number of haemoglobin molecules in one red…

Q13 · Which statements about a peptide bond are correct?

Q14 · Which graph correctly shows the activation energy of a reaction when an enzyme is added?

Q15 · The enzyme lactase is found in the membranes of epithelial cells lining the small…

Q16 · A student wrote three statements about cell signalling

Q17 · At which stages of mitosis are chromosomes composed of two chromatids that are held…

Q18 · The jellyfish, Turritopsis dohrnii, is described as being immortal

Q19 · Some chemicals, used to stop tumour growth, work by preventing the DNA double helix from…

Q20 · Four nucleotides, A, B, C and D, each consist of three phosphate groups, a nitrogenous…

Q21 · The statements describe the process of translation

Q22 · The sequence of amino acids in a section of a polypeptide is: ……

Q23 · What contributes to the upward movement of water in a xylem vessel of a plant?

Q24 · The diameter of a tree trunk usually decreases slightly during the day

Q25 · The diagram shows a transverse section of a stem

Q26 · The diagram shows a xerophytic leaf in different conditions, P and Q

Q27 · Different substances, such as sucrose and amino acids, can move in different directions…

Q28 · The statements list some of the events in a cardiac cycle

Q29 · Which row correctly identifies components of both lymph and tissue fluid?

Q30 · Which row is correct for the mean blood pressure in different parts of the human…

Q31 · Which mechanism accounts for the way most of the carbon dioxide is transported in blood?

Q32 · The graph shows the dissociation curves for haemoglobin at two different partial…

Q33 · The table shows the partial pressure of carbon dioxide and oxygen in two blood vessels

Q34 · Which graph shows the effect of carbon monoxide on the percentage saturation of…

Q35 · Which row shows the correct methods of transmission of the named pathogens?

Q36 · Which disease is caused by a eukaryote?

Q37 · What is the initial mechanism by which bacteria become resistant to antibiotics?

Q38 · What are functions of T-lymphocytes?

Q39 · What is correct about the role of memory cells in long-term immunity?

Q40 · Which events result in a person developing actively acquired immunity?

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