Cambridge A Level Biology 9700 — 2020 Oct/Nov Paper 1 · Variant 3

Question 1

1 What are the appropriate units for measuring diameters of alveoli, diameters of white blood cells and the width of cell walls? diameters of diameters of width of alveoli white blood cells cell walls A mm mm nm B mm m m C m mm m D m m nm

Accepted Answer

D

Question 2

2 The actual diameter of a prokaryotic cell is 0.5 m. An electron micrograph of the cell has a magnification of 50 000. What is the diameter of the cell in the image? A 2.5  10–1 mm B 2.5  100 mm C 2.5  101 mm D 2.5  102 mm

Accepted Answer

C

Question 3

3 The electron micrograph shows some cell structures. Some cell structures are listed. 1 nucleolus 2 chloroplast 3 microtubules 4 ribosomes 5 mitochondria 6 plasmodesmata Which cell structures can be seen in the electron micrograph? A 1, 2, 3 and 4 B 1, 4, 5 and 6 C 2, 3, 5 and 6 D 2, 4, 5 and 6

Accepted Answer

B

Question 4

4 Which part of the cell is often continuous with the rough endoplasmic reticulum? A cell surface membrane B Golgi body C mitochondrion D nuclear envelope

Accepted Answer

D

Question 5

5 Which statements about ATP are correct? 1 It is produced in chloroplasts. 2 It is used during protein synthesis. 3 It contains deoxyribose. 4 It is used in facilitated diffusion. 5 It is used to load sucrose into companion cells. A 1, 2 and 5 B 1, 3 and 5 C 2, 3, 4 and 5 D 2 and 4 only

Accepted Answer

A

Question 6

6 Four students were asked to match the function with the appearance of some cell structures in an animal cell. The functions were listed by number. 1 mRNA passes through to the ribosome 2 organises microtubules to produce the spindle during cell division 3 synthesis of lipids The appearances were listed by letter. V membranes which surround an enclosed inner cavity W non-membrane-bound, spherical structures X a double membrane with pores Y non-membrane-bound, cylindrical structures Z membrane-bound sacs, arranged as a flattened stack Which student correctly matched the numbered functions with the appearance of the cell structure? 1 2 3 A V W Z B V Y W C X W V D X Y V

Accepted Answer

D

Question 7

7 A student carried out tests for biological molecules on the same sample of milk. The tests and their results were as follows. ● Heating to 80 C with Benedict’s solution gave a red colour. ● Boiling with acid, followed by neutralisation, then heating to 80 C with Benedict’s solution also gave a red colour. ● Adding Biuret solution gave a purple colour. ● Adding iodine solution gave a yellow colour. Which biological molecules must be present in the milk? 1 non-reducing sugars 2 protein 3 reducing sugars 4 starch A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 3 and 4

Accepted Answer

C

Question 8

8 Which row is correct for carbohydrates? monomer polymer macromolecule A fructose amylose cellulose B glucose deoxyribose amylopectin C monosaccharide glycogen deoxyribose D sucrose starch glycogen

Accepted Answer

A

Question 9

9 Which molecules contain 1,6 glycosidic bonds? 1 amylopectin 2 glycogen 3 starch 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 Which row correctly shows the ratio of carbon atoms to hydrogen atoms for glucose, a saturated fatty acid and sucrose? ratio of carbon atoms to hydrogen atoms saturated fatty glucose sucrose acid A 1 : 2 1 : 2 1 : 1.8 B 1 : 2 4 : 1 1 : 2 C 2 : 1 1 : 4 2 : 1 D 2 : 1 2 : 1 1.8 : 1

Accepted Answer

A

Question 11

11 Which row shows a correct comparison between a phospholipid molecule and a triglyceride molecule? phospholipid molecule triglyceride molecule A contains a hydrophobic phosphate group is a hydrophobic molecule B contains one glycerol molecule contains three glycerol molecules C fewer ester bonds more ester bonds D more fatty acids fewer fatty acids

Accepted Answer

C

Question 12

12 Adult human haemoglobin typically consists of two  chains and two  chains. Approximately 5% of humans have one amino acid in the  chain that has been changed. This change affects the structure and stability of haemoglobin. Which levels of protein structure could be affected in the haemoglobin of the humans with the changed amino acid? A primary only B primary and quaternary only C secondary, tertiary and quaternary only D primary, secondary, tertiary and quaternary

Accepted Answer

D

Question 13

13 Lysozyme occurs in human tears, saliva, milk and mucus. Lysozyme has a role in the immune system and hydrolyses peptidoglycan. Which description of lysozyme is correct? A It is an extracellular antibody. B It is an intracellular antibody. C It is an extracellular antibacterial protein. D It is an intracellular antibacterial protein.

Accepted Answer

C

Question 14

14 Which letter in the flow diagram shows the effect of adding a competitive inhibitor to an enzyme-catalysed reaction? is a reversible reaction yes no affects the Vmax value affects the Km value of the enzyme of the enzyme yes no yes no A B C D

Accepted Answer

B

Question 15

15 The cell surface membrane structure is described as a ‘fluid mosaic’. Which statement describes the ‘mosaic’ part of the cell surface membrane? A the different patterns that are obtained by the moving phospholipid molecules B the random distribution of cholesterol molecules within the phospholipid bilayer C the regular pattern produced by the phospholipid heads and membrane proteins D the scattering of the different proteins within the phospholipid bilayer

Accepted Answer

D

Question 16

16 Solute X is at a higher concentration outside a cell than in the cytoplasm. Which processes may allow solute X to be moved through the cell surface membrane? A active transport, diffusion and facilitated diffusion B active transport, diffusion and osmosis C diffusion, facilitated diffusion and osmosis D exocytosis, facilitated diffusion and osmosis

Accepted Answer

A

Question 17

17 Three molecules found in prokaryotes are listed. 1 phospholipid 2 protein 3 peptidoglycan Which molecules are found in prokaryotic cell surface membranes? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Accepted Answer

B

Question 18

18 What happens to the surface area to volume ratio of a cube when the length of each side is doubled? A The ratio decreases by a quarter. B The ratio decreases by half. C The ratio doubles. D The ratio increases by four times.

Accepted Answer

B

Question 19

19 Three parts of a chromosome and their functions are listed. part function p1 centromere f1 holds the coils of DNA together p2 histone proteins f2 holds two chromatids together p3 telomere f3 prevents loss of genes Which part is matched with its correct function? A p1 and f2 B p2 and f2 C p2 and f3 D p3 and f1

Accepted Answer

A

Question 20

20 Which features of mitosis are important for a single-celled organism? 1 asexual reproduction 2 production of genetically identical cells 3 growth A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Accepted Answer

B

Question 21

21 Some events in the cell cycle are listed. Which events are part of mitosis? 1 interphase 2 metaphase 3 cytokinesis A 1, 2 and 3 B 1 and 3 only C 1 only D 2 only

Accepted Answer

D

Question 22

22 Which row represents the correct features of guanine?

joins its
has a ; .
. : . . complementary pairs with
single ring IS @ purine base via three thymine
structure
hydrogen bonds
A v Jv x v
B v x v x
Cc x Jv v x
D x x v v

key
/ = correct

X = not correct

Accepted Answer

C

Question 23

23 Bacteria were grown in a medium containing 15N. After several generations, all of the DNA contained 15N. Some of these bacteria were transferred to a medium containing the common isotope of nitrogen, 14N. The bacteria were allowed to divide once. The DNA of some of these bacteria was extracted and analysed. This DNA was all hybrid DNA containing equal amounts of 14N and 15N (14N / 15N). In another experiment, some bacteria from the medium with 15N were transferred into a medium of 14N. The bacteria were allowed to divide three times. The DNA of some of these bacteria was extracted and analysed. What is the composition of this DNA? A B 100 100 75 75 percentage percentage 50 50 of DNA of DNA 25 25 0 0 14N 14N / 15N 14N 14N / 15N C D 100 100 75 75 percentage percentage 50 50 of DNA of DNA 25 25 0 0 14N 14N / 15N 14N 14N / 15N

Accepted Answer

C

Question 24

24 A molecule of transfer RNA (tRNA) has the anticodon sequence UAC. What will be the corresponding nucleotide sequence in the DNA? A ATG B AUG C TAC D TUG

Accepted Answer

C

Question 25

25 Some of the features present in transport tissues in plants are listed. 1 lignified walls 2 cytoplasm 3 many mitochondria 4 pits 5 plasmodesmata 6 sieve plates Which of these features are present in xylem vessel elements? A 1, 2, 4 and 5 B 1 and 4 only C 2, 3, 5 and 6 D 2, 3 and 5 only

Accepted Answer

B

Question 26

26 The diameter of a tree trunk usually decreases slightly during the day and increases slightly at night. Which three environmental factors, if increased, could cause the largest decrease in diameter? A humidity, temperature, wind speed B humidity, light intensity, temperature C humidity, light intensity, wind speed D light intensity, temperature, wind speed

Accepted Answer

D

Question 27

27 Sucrose moves within a phloem sieve tube from a source to a sink by mass flow. Which type of gradient within the phloem sieve tube between the source and sink causes the movement of sucrose? A diffusion gradient B hydrostatic gradient C concentration gradient D water potential gradient

Accepted Answer

B

Question 28

28 Which are present in the walls of veins?

endothelium smoomn elastic tissue co fagen
A Jv x Jv Jv
B x Jv x JV
Cc Jv Jv Jv x
D Jv Jv Jv Jv

key
/ = present

X = not present

Accepted Answer

D

Question 29

29 Which row is correct for the location of a type of molecule or cell?

type of molecule or cell blood lymph ou
A antibodies Xx v v
B plasma proteins Jv x x
Cc lymphocytes v v v
D phagocytes v x v

key
/ = present

X = not present

Accepted Answer

C

Question 30

30 What effect does decreasing carbon dioxide concentration have on haemoglobin? A It is less efficient at taking up oxygen and less efficient at releasing oxygen. B It is less efficient at taking up oxygen and more efficient at releasing oxygen. C It is more efficient at taking up oxygen and less efficient at releasing oxygen. D It is more efficient at taking up oxygen and more efficient at releasing oxygen.

Accepted Answer

C

Question 31

31 Why does the red blood cell count increase in humans as they start living at high altitude? A to allow more carbon dioxide to be excreted by the lungs, preventing a fall in blood pH B to allow more oxygen to be taken up by the haemoglobin as the partial pressure of oxygen is lower C to allow more oxygen to be taken up by the lungs as there is a lower percentage of oxygen in the air D to allow more oxygen to be transported as the affinity of haemoglobin for oxygen is lowered

Accepted Answer

B

Question 32

32 The diagram shows a photomicrograph of part of a bronchus. Which label identifies smooth muscle? D A B C

Accepted Answer

C

Question 33

33 Which statements about all bronchioles are correct? 1 They have epithelium. 2 They have goblet cells. 3 They have muscle tissue. A 1, 2 and 3 B 1 and 3 only C 2 only D 3 only

Accepted Answer

B

Question 34

34 Which row shows the effects of emphysema? number of alveoli elastin capillaries A burst less decrease B burst more increase C shrink less increase D shrink more decrease

Accepted Answer

A

Question 35

35 Which row is correct? infectious or disease transmission non-infectious A HIV/AIDS genetic infectious B lung cancer pathogen infectious C sickle cell anemia genetic non-infectious D TB pathogen non-infectious

Accepted Answer

C

Question 36

36 The diagrams show the result of incubating two species of bacteria, P and R, on separate Petri dishes each containing nutrient agar. Three filter paper discs have been added to each Petri dish. bacteria N N key N = no antibiotic X = antibiotic X X Y X Y Y = antibiotic Y bacteria P bacteria R Which statement is correct? A Antibiotics X and Y are resistant to bacteria P. B Bacteria P are resistant to both antibiotics. C Bacteria R have a mutation that makes them resistant to antibiotic Y. D N is a control disc showing bacteria R grow when antibiotic Y is not present.

Accepted Answer

D

Question 37

37 The statements are about infectious diseases. 1 Disease may be spread between humans by contact. 2 Disease-causing organism has many antigenic variations. 3 Spread of disease may be influenced by climate. 4 A vaccination programme is available. Which row matches the correct statement numbers with each disease? cholera measles malaria A 1 1 and 2 1 and 3 B 1 and 4 4 2 C 2 and 3 1 and 3 1 and 4 D 4 1 and 4 2 and 3

Accepted Answer

D

Question 38

38 Muscle cells have cell surface receptors for the neurotransmitter, ACh. These receptors allow the muscle to respond to a nerve impulse. In the condition myasthenia gravis, the helper T cells stimulate a clone of B cells to become plasma cells and secrete antibodies that bind to and block these ACh receptors. The muscles cannot be stimulated and begin to break down. A short-term treatment for myasthenia gravis is to inject monoclonal antibodies into the blood. What is the target of these monoclonal antibodies? A antibodies that bind to ACh receptors B muscle cell surface ACh receptors C plasma cells secreting anti-ACh receptor antibodies D the stimulating neurotransmitter ACh

Accepted Answer

A

Question 39

39 The diagram shows the simplified structure of an antibody. X U V W Which statement is correct? A U and X allow the antibody to bind to two different antigens. B V allows the antibody to fit around the antigen. C W can bind to one specific antigen. D X can bind with a specific phagocyte receptor.

Accepted Answer

B

Question 40

40 Why have vaccination programmes eradicated smallpox but not TB? A Vaccination can provide immunity only for smallpox but not for TB. B Only TB is associated with poor living conditions. C The smallpox virus showed little variation of antigens. D The TB pathogen is a bacterium and the smallpox pathogen is a virus.

Accepted Answer

C

Question paper16 pages

Mark scheme3 pages

Questions as text

Q1 · What are the appropriate units for measuring diameters of alveoli, diameters of white…

Q2 · The actual diameter of a prokaryotic cell is 0.5 m

Q3 · The electron micrograph shows some cell structures

Q4 · Which part of the cell is often continuous with the rough endoplasmic reticulum?

Q5 · Which statements about ATP are correct?

Q6 · Four students were asked to match the function with the appearance of some cell…

Q7 · A student carried out tests for biological molecules on the same sample of milk

Q8 · Which row is correct for carbohydrates?

Q9 · Which molecules contain 1,6 glycosidic bonds?

Q10 · Which row correctly shows the ratio of carbon atoms to hydrogen atoms for glucose, a…

Q11 · Which row shows a correct comparison between a phospholipid molecule and a triglyceride…

Q12 · Adult human haemoglobin typically consists of two  chains and two  chains

Q13 · Lysozyme occurs in human tears, saliva, milk and mucus

Q14 · Which letter in the flow diagram shows the effect of adding a competitive inhibitor to an…

Q15 · The cell surface membrane structure is described as a ‘fluid mosaic’

Q16 · Solute X is at a higher concentration outside a cell than in the cytoplasm

Q17 · Three molecules found in prokaryotes are listed

Q18 · What happens to the surface area to volume ratio of a cube when the length of each side…

Q19 · Three parts of a chromosome and their functions are listed

Q20 · Which features of mitosis are important for a single-celled organism?

Q21 · Some events in the cell cycle are listed

Q22 · Which row represents the correct features of guanine?

Q23 · Bacteria were grown in a medium containing 15N

Q24 · A molecule of transfer RNA (tRNA) has the anticodon sequence UAC

Q25 · Some of the features present in transport tissues in plants are listed

Q26 · The diameter of a tree trunk usually decreases slightly during the day and increases…

Q27 · Sucrose moves within a phloem sieve tube from a source to a sink by mass flow

Q28 · Which are present in the walls of veins?

Q29 · Which row is correct for the location of a type of molecule or cell?

Q30 · What effect does decreasing carbon dioxide concentration have on haemoglobin?

Q31 · Why does the red blood cell count increase in humans as they start living at high…

Q32 · The diagram shows a photomicrograph of part of a bronchus

Q33 · Which statements about all bronchioles are correct?

Q34 · Which row shows the effects of emphysema?

Q35 · Which row is correct?

Q36 · The diagrams show the result of incubating two species of bacteria, P and R, on separate…

Q37 · The statements are about infectious diseases

Q38 · Muscle cells have cell surface receptors for the neurotransmitter, ACh

Q39 · The diagram shows the simplified structure of an antibody

Q40 · Why have vaccination programmes eradicated smallpox but not TB?

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