GCSE Biology Higher Paper 3

Question 1 [4 marks]

Cell Structure and Transport

A student views a cheek cell using a light microscope.

The image of the cell measured on the photograph is 24 mm wide.

The actual width of the cheek cell is 60 micrometres.

Calculate the magnification of the image. Give your answer as a whole number.

Question 2 [4 marks]

Hormones and Homeostasis

A patient's blood glucose concentration was 5.5 mmol/l at 08:00 and rose to 9.5 mmol/l at 08:30 after breakfast.

Calculate the mean rate of increase in blood glucose concentration, in mmol/l per minute, over this time.

Question 3 [4 marks]

Cell Division and Stem Cells

A single cell divides by mitosis every 20 minutes.

Starting from one cell, calculate how many cells will be present after 2 hours, assuming every cell divides on schedule.

Question 4 [4 marks]

Digestion and the Circulatory System

In an investigation of lipase activity, 12 cm^3 of gas was produced in 4 minutes.

Calculate the mean rate of gas production, in cm^3 per minute, then calculate how long it would take to produce 45 cm^3 of gas at this rate.

Question 5 [5 marks]

Pathogens and Communicable Disease

At the start of an outbreak, one person is infected. Each infected person then infects 3 new people before recovering, and this repeats for further rounds of infection.

Calculate the total number of people who have been infected in total after 3 further rounds of infection beyond the original case.

Question 6 [5 marks]

Genetics and Inheritance

In a large sample of 240 pea plants grown from a cross expected to give a 1:2:1 ratio of genotypes, calculate how many plants would be expected of each genotype.

Question 7 [5 marks]

The Nervous System and Reflexes

Nerve impulses must cross a synapse (gap) to pass from one neurone to the next.

Explain how a nerve impulse crosses a synapse.

Question 8 [5 marks]

Human Defence Systems and Treating Disease

Explain why new medical drugs must be tested and trialled before they are prescribed to patients, describing the main stages involved.

Question 9 [6 marks]

Ecosystems and Material Cycles

In a food chain of producer -> primary consumer -> secondary consumer -> tertiary consumer, only 10% of energy is transferred between each trophic level. A population of tertiary consumers (eagles) contains 80 kJ of energy stored as biomass.

Calculate the energy that must have been available at the secondary consumer, primary consumer and producer levels to support this, and explain why an ecosystem can typically support far fewer tertiary consumers than producers.

Question 10 [6 marks]

Respiration and Exercise

Aerobic respiration of one mole of glucose releases about 2900 kJ of energy. Anaerobic respiration (producing lactic acid) of one mole of glucose releases only about 120 kJ of energy.

Calculate how many times more energy is released by aerobic respiration than anaerobic respiration of the same amount of glucose, and explain why muscle cells still respire anaerobically during vigorous exercise despite this being far less efficient.

Question 11 [6 marks]

Evolution and Natural Selection

Two populations of the same species become separated by a new river, and cannot interbreed for many thousands of years.

Explain how this separation could eventually lead to the formation of two separate species, and explain how scientists could use DNA evidence to confirm that speciation has occurred.

Question 12 [6 marks]

Photosynthesis

A student uses the inverse square law to investigate how distance from a lamp affects light intensity reaching pondweed.

Light intensity is proportional to 1/distance^2.

At a distance of 20 cm, the light intensity is 4 arbitrary units.

Calculate the light intensity at a distance of 40 cm from the lamp, and explain what this means for the expected rate of photosynthesis at 40 cm compared with 20 cm.