Year 12 Mock AS 2023 Biology Paper 2

Question 1

Name two biological molecules that can be coded for by a gene

Do not include a polypeptide or protein in your answer

Answer 1

Any two from:
rRNA;
(Pre) mRNA;
tRNA

Question 2

suggest how the structure of rough endoplasmic reticulum is different from the structure of smooth endoplasmic reticulum and how this is related to their functions

Answer 2

1. Less phospholipids in rough
   OR
   More protein/glycoprotein in rough
   OR
   Presence of ribosomes in rough;
2. (More protein/glycoprotein/ribosomes)
   Rough – production/transport of proteins;
3. (More phospholipid)
   Smooth –
   production/modification/packaging/transport of
   lipids

Question 3

Complete the passage with the appropriate terms

ATP synthase comprises several polypeptide chains so it is said to have a ———– structure. It catalyses the synthesis of an ATP molecule by a ——— reaction this involves the ——– of a water molecule The ATP synthase in figure 1 is in a mitochondrion so would catalyse reactions during ——

Answer 3

Quaternary
Condensation/phosphorylation/redox
Release/loss/formation
(Aerobic) respiration;;
All correct = 2 marks,
2–3 correct = 1 mark,
0–1 correct = 0 marks

Question 4

suggest how the shape of the ATP synthase allows it to have these two functions

Catalyses the synthesis of ATP

Allows the movement of H+ ions

Answer 4

(Catalyses the synthesis of ATP)
1. Active site complementary to ADP + Pi;
2. Enzyme-substrate complex forms;
(Allows the movement of H+ ions)
3. Channel (in membrane/protein/enzyme);
4. Allows facilitated diffusion of H+
OR
(Channel) has tertiary structure specific for (only)
H+
;

Question 5

Galacto - oligosaccharides are polymers of galactose

Explain why GOS are described as polysaccharides

Answer 5

Any two from:
1. Galactose is a monosaccharide/monomer;
2. (Polysaccharide is a) carbohydrate polymer;
3. (Several) monosaccharides/monomers/galactose
joined by condensation reactions
OR
(Several) monosaccharides/monomers/galactose
joined by glycosidic bonds;

Question 6

Explain why amylase produced in the human digestive system does not digest GOS

Answer 6

1. Active site (only) complementary to starch
   OR
   Active site not complementary to GOS;
2. (Due to) tertiary structure;

Question 7

Suggest how GOS can work as a prebiotic

Answer 7

1. Provides galactose/sugar/monosaccharide;
2. (Bacteria use the galactose/sugar) for
   respiration;
3. (Bacteria use the galactose/sugar) for binary
   fission;

Question 8

Give the order of structures through which blood will pass through as it enters the heart and flows through the left ventricle

Answer 8

Aorta 6 Pulmonary vein 1
Left
atrioventricular
valve
3 Left semi-lunar
valve 5
Right
atrioventricular
valve
Vena cava
Left atrium 2 Left ventricle 4
Right atrium Right ventricle
Pulmonary artery Right semi-lunar
valve
All correct 2 marks,
3–4 correct 1 mark,
0–2 correct 0 marks

Question 9

Name the type of blood vessel that controls blood flow to muscles and explain how these blood vessels change blood flow during exercise

Answer 9

1. Arteriole;
2. (Circular/smooth) muscle relaxes;
3. Vasodilation increases blood flow
   OR
   Widens/dilates (lumen of) blood vessel so
   increases blood flow;

Question 10

suggest and explain the similarities and differences in the causes of genetic variation within these rice populations

Answer 10

(Similarities)
1. (Both populations) have (variation due to)
independent segregation/assortment (of
chromosomes/chromatids);
2. (Both populations) have (variation due to)
random fertilisation (of gametes);
3. Both (populations) have (further) mutations;
(Difference)
4. Crossing over causes variation in non-mutant
only;

Question 11

Describe the hydrolysis reactions involved in the digestion of triglycerides

Do not write about the activity of lipase

Answer 11

1. Breaking of ester bonds;
2. By addition of water;

Question 12

CEL is activated by bile salts binding to the enzyme

Describe two other functions of bile salts

Answer 12

1. Emulsify lipids/fats;
2. Increases surface area (of lipid/fat) for
   (increased) lipase activity;
3. Form micelles;

Question 13

Describe how natural selection may have led to all mammals in a population producing CEL

Answer 13

1. Mutation results in (a new) allele;
2. Those with the (new) allele able to digest
   milk/triglycerides;
3. Individuals with CEL/allele more likely to (survive
   and) reproduce;
4. Directional selection;
5. Increase in frequency of (this) allele in
   population;

Question 14

During anaphase, the spindle exerts 3 x 10^-11 N of force on each chromatid
This force generates 6 x 10^-19 W of power

Calculate the speed of movement in nm s-1 of one chromatid during anaphase using the following equation: P = F X V
where P = power in W
F = force in N
V = speed in m s-1

Answer 14

Correct answer of 20 = 2 marks;;
1 mark for evidence of 2 × 10–8 (m s–1)

Question 15

State the range of possible concentrations of a protein solution that sinks in 75 g kg-1 copper sulphate and floats in 100g kg-1 copper sulphate solution

Minimum concentration

Maximum concentration

Answer 15

16.5 and 22;

Question 16

Consequences of measurement error for Tom’s blood

Consequences of measurement error for Lucy’s blood

Answer 16

Any three from:
(Tom)
1. (Healthy donor) not allowed to donate;
2. Less blood collected
OR
Fewer patients treated;
3. Cause Tom anxiety (about his health);
(Lucy)
4. (Gives blood) when it may not be safe (for her) to
do so;
5. (Her blood) may not help patients;
6. Her (missed) low haemoglobin goes untreated

Question 17

Outline the similarities in, and the differences between, the structures of DNA and RNA molecules

Answer 17

Similarities
1. Polymers of nucleotides;
2. (Nucleotide has) pentose, (nitrogen-containing
organic) base and a phosphate (group);
3. Cytosine, guanine and adenine (as bases);
4. Have phosphodiester bonds;
Differences
5. Deoxyribose v ribose;
6. Thymine v uracil;
7. Long v short;
8. Double helix/stranded v single stranded