Missed marks 2020 Paper 1

Describe how energy for the photosynthesis reaction is gained by plants. [1 mark]

Light is captured by chloroplasts

Students investigated the effect of temperature on the rate of photosynthesis. Suggest one possible cause of the anomalous result. [1 mark]

Temperature changed

Explain how the nitrate ions in Figure 4 are transported into the root hair cell. [3 marks]

Active transport

Energy is needed

To move the nitrate ions from lower concentration to higher concentration

Describe what happens during each stage of the cell cycle. [4 marks]

Stage 1 – Chromosomes replicate and sub-cellular structures replicate.

Stage 2 – Chromosomes line up in the centre of the cell and cell fibres pull the 2 arms of each chromosome to opposite ends of the cell.

Stage 3 – Cell membrane and cytoplasm divide to form two cells.

Explain the ‘lock and key theory’ of enzyme action. [3 marks]

Enzyme and substrate fit each other exactly as they are complementary

Substrate is broken down

Products are released

How do thorns defend the gorse plant? [1 mark]

Prevents animals from damaging it

Describe the effects of liver failure on the body. [4 marks]

If liver fails, glycogen stores may not form

So levels of glucose in the body are out of control and diabetes may occur

If liver fails, no bile is produced

So lipids are not emulsified, so surface area of lipids is not increased, so enzymes won’t work efficiently, therefore weight loss may occur

Describe how the clinical trials should be carried out. [6 marks]

Phase 1 of the clinical trials should involve the giving of the mAbs treatment to healthy volunteers to check for toxicity.

Phase 2 of the clinical trials should involve the giving of the mAbs treatment to a small group of patients with the disease at different doses to find the optimum dose.

Phase 3 of the clinical trials should involve the giving of the mAbs treatment to a large group of patients with the disease using double blind trials where neither the doctor nor the patient know whether the patient is receiving a placebo or a mAbs treatment. This is done to avoid bias from the doctor or the placebo effect from the patient.

These trials should each be done over a long period of time.