Mock

Question 1

1.2. Give 1 similarity and 1 difference between the structures of starch & cellulose (2)

Answer 1

(1) both contain hydrogen bonds
(2) starch = made up of a-glucose
cellulose = made up of B-glucose

Question 2

3.3. Many insects live on land. Insects living on land have features that reduce water loss. Explain how 2 of the features reduce water loss. (2)

Answer 2

2 of:
(1) spiracles can close SO less evaporation
(2) hairs around spiracles trap water SO WP gradient is reduced
(3) waterproof covering SO less evaporation

Question 3

3.5. The damselfly nymph is a predator. Suggest how an efficient gas exchange system helps the damselfly nymph to survive. (2)

Answer 3

(1) more oxygen
(2) more respiration for muscle movement

Question 4

4.4. Explain the advantage to the penguin of having an oxygen dissociation curve to the left of the curve of the goose. (3)

Answer 4

(1) higher affinity for oxygen
(2) so it only unloads when pO2 in tissues is LOW
(3) to help conserve the oxygen so it can stay underwater longer

Question 5

4.5. During a penguins dive, the oxygen dissociation curve gradually shifts to the right. Explain what causes this shift. (2)

Answer 5

(1) respiration = Increases CO2 conc
(2) DEC affinity of haemoglobin for oxygen

Question 6

5.2. In the chromatography exp, what is the importance of each step: (3)
1. Crushing leaves
2. Pigment spot above solvent
3. Marks position of solvent front

Answer 6

1. Extracts pigments
2. Pigment spot is not washed off the paper
3. Position is recorded before the paper dries

Question 7

6.5. Vancomycin is an antibiotic that can be used to treat S. aureus infections. It prevents the formation of pentaglycine bridges between peptide chains in murein. Suggest how it prevents the growth of a population of bacteria. (2)

Answer 7

(1) prevents the synthesis of cell walls
(2) so bacteria can’t reproduce

Question 8

8.2. In the induced fit model, explain how the binding of a substrate to an enzyme can result in the formation of an E-S complex. (2)

Answer 8

(1) changes shape of the active site
(2) so it becomes complementary to the substrate

Question 9

9.1. A student uses a microscope to investigate plasmolysis in onion cells. Describe how the student should sample their cells. (2)

Answer 9

(1) count a large number of cells
(2) random sampling

Question 10

9.6. The student wants to use methylene blue (MB) to stain the onion cells in the 0.6 mol dm3 NaCl solution to make them easier to count. Suggest how MB could affect the results for that solution’s slide (1)

Answer 10

(1) it’ll alter the water potential of the solution so the percentage of cells plasmolysed changes