Examiner reports

Question 1

Explain how the person’s eye could adjust to form a clear image of a nearer object

Answer 1

ciliary muscles contract-smaller diameter
-suspensory ligaments loosen
-lens thickens-lens is more convergent
light rays focused on retina.

Question 2

Explain why a long-sighted person has difficulty seeing near objects clearly

Answer 2

eye(-ball) is (too) short (so) light ‘focuses’ behind retina

Question 3

Long-sightedness can be corrected by wearing spectacles.
Describe how spectacle lenses can correct long-sightedness.

Answer 3

convex / converging lens
light rays refracted
(inwards) more
light rays focused on retina

Question 4

Explain two biological reasons why most doctors think that a kidney transplant is a
better method of treatment than dialysis.

Answer 4

changes in concentrations substances are minimised
less chance of causing damage to body cells.
- blood not in contact with machine less of infection.

Question 5

Suggest three ways the scientists could maintain a high rate of reproduction in the bacterial culture

Answer 5

add (more) oxygen
* increase temperature
* remove toxins.

Question 6

Farming techniques have changed in recent years.
Describe:
* why more land is being used for farming
* how increased farming has decreased biodiversity

Answer 6

increasing population requires more food.
* loss of hedgerows (to make fields larger)
* loss of habitat
* consequence of loss of habitat eg (change in) migration
more methane (from cows)
* climate change

Question 7

Suggest one reason why some people are concerned about the use of golden rice

Answer 7

high cost of seeds
* may have too much vitamin A .

Question 8

Describe one similarity between the processes of mitosis and meiosis.

Answer 8

• DNA replicates (once)

Question 9

Describe three differences between the processes of mitosis and meiosis.

Answer 9

mitosis- two (daughter) cells but meiosis produces four (daughter) cells
* one cell division in mitosis/two in meiosis
* mitosis-genetically identical cells, but meiosis
produced genetically different cells.

Question 10

Describe how the brain receives information about light entering the eye

Answer 10

(cells in) retina sensitive to light impulse
passes along (sensory) neurone
(along) optic nerve

Question 11

Give three reasons why the fossil record is not clear for older species.

Answer 11

• fossils buried deep(er) so hard(er) to find
• fossils smaller so harder to find
• more likely to be destroyed by
  geological activity.

Question 12

Give one disadvantage and one advantage of mass extinction events.
Answer in terms of evolution.

Answer 12

• loss of potential, future biodiversity.
  ADV-allows evolution of new species.

Question 13

How could the student keep the milk at a constant temperature for 5 days?

Answer 13

(put beaker in a) water bath.

Question 14

Describe:
* how microorganisms in the layers of soil help to recycle chemicals in the
dead plants
* how the chemicals are used again by living plants.

Answer 14

in microorganisms
* digestion or large molecules
* respiration
* production of carbon dioxide
* release of mineral ions or named example such as nitrate
in plants
* carbon dioxide used in photosynthesis
* making glucose
* (named) ions taken in by roots-active transport
* nitrate ions for making amino acids.

Question 15

How does the thermoregulatory centre send information to sweat glands in the skin?

Answer 15

via nerve(s) / neurones.

Question 16

Describe how hormones control the menstrual cycle

Answer 16

FSH-stimulates maturation of egg
oestrogen-inhibits FSH production/stimulates LH production
LH-stimulates ovulation
progesterone-inhibits FSH and LH production
oestrogen/progesterone-maintain the uterus lining

Question 17

Some of the leaves from the gardener’s strawberry plant die.
The dead leaves fall off the strawberry plant onto the ground.
The carbon in the dead leaves is recycled through the carbon cycle.
Explain how the carbon is recycled into the growth of new leaves.

Answer 17

statements:
* (carbon compounds in) dead leaves are broken down by microorganisms / decomposers / bacteria / fungi
* photosynthesis uses carbon dioxide
explanations:
* (microorganisms) respire
* (and) release the carbon from the leaves as carbon dioxide
* plants take in the carbon dioxide released to use in photosynthesis to produce
glucose
use of carbon in growth:
* glucose produced in photosynthesis is used to make amino acids / proteins / cellulose
* (which are) required for the growth of new leaves

Question 18

Describe how different environmental factors affect:
*the direction of growth of roots/shoots.
In your answer, you should refer to the role of plant hormones.

Answer 18

• light
  allow phototropism
• (direction of the force of) gravity
  allow gravi / geotropism
• moisture / water.
  allow hydrotropism
  effects on direction of growth
• shoots grow upwards
• shoots grow towards light
• shoots grow against (the force of) gravity
• roots grow downwards
• roots grow towards moisture
• roots grow towards (the force of) gravity.
  allow reference to ‘positive’ and ‘negative’ in terms of tropisms as indicating direction of growth
  hormone
• reference to auxin
  allow other named hormone(s)
• unequal distribution of hormone causes unequal growth (rates).
  allow higher concentration of hormone causes faster growth in shoots
  allow higher concentration of hormone causes slower growth in roots

Question 19

Suggest two ways in which contamination of the fermenter by microorganisms could be prevented.

Answer 19

• steam/heat water (before use)
• sterilise air intake