OCR GCSE Biology 2027 Predicted Practice Paper — Paper 3 Higher

Answer ALL questions. Write your answers in the spaces provided. You must write down all the stages in your working.

Section A

Answer all questions. This paper is written in an OCR Gateway Biology Paper 1 practice style.

• 1

  Question A1 (9 marks)

  A student investigates osmosis using cylinders cut from a raw swede (a root vegetable). Six identical cylinders, each of starting mass 4.00 g, are placed in sucrose solutions of different concentration for 60 minutes, then blotted and reweighed. Results: Concentration (mol/dm^3): 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 Final mass (g): 4.48, 4.24, 4.00, 3.68, 3.44, 3.20 (a) Define osmosis. [2] (b) Calculate the percentage change in mass for the cylinder in the 1.0 mol/dm^3 solution. [2] (c) Using the data, estimate the concentration of sucrose solution that is isotonic with the swede cell contents, and explain your reasoning. [2] (d) Explain, in terms of water potential, why the cylinder in distilled water (0.0 mol/dm^3) gained mass. [3]

  (Total for Question A1 is 9 marks)
• 2

  Question A2 (9 marks)

  Amylase is an enzyme that breaks down starch. A student times how long amylase takes to fully digest a fixed amount of starch at different temperatures. They test for starch every 10 seconds using iodine solution. Temperature (degrees C): 10, 20, 30, 40, 50, 60 Time to digest starch (s): 300, 180, 90, 60, 150, no digestion (a) Name the food group that starch belongs to, and name the smaller molecule produced when amylase breaks down starch. [2] (b) State the optimum temperature shown by these results and calculate the rate of reaction at 30 degrees C in arbitrary units (1/time). [2] (c) Explain, using ideas about kinetic energy and collisions, why the reaction is faster at 40 degrees C than at 10 degrees C. [2] (d) Explain why no digestion occurs at 60 degrees C. Use the term 'active site' in your answer. [3]

  (Total for Question A2 is 9 marks)
• 3

  Question A3 (9 marks)

  A grower studies the rate of photosynthesis of tomato plants in a greenhouse. The rate is measured as the volume of oxygen released per minute. (a) Write the word equation for photosynthesis. [2] (b) The grower increases the light intensity from low to high while keeping temperature and carbon dioxide concentration constant. At low light intensity the rate increases steeply as light increases, but at high light intensity the rate stops increasing and levels off. Explain, using the idea of limiting factors, what is happening at high light intensity. [3] (c) The grower burns a paraffin heater in the greenhouse. Explain two ways in which this could increase the rate of photosynthesis. [2] (d) Suggest why measuring oxygen released may underestimate the true rate of photosynthesis in the plant. [2]

  (Total for Question A3 is 9 marks)
• 4

  Question A4 (9 marks)

  The diagram context: air passes down the trachea, into the bronchi, then bronchioles, ending in tiny air sacs called alveoli, which are surrounded by capillaries. (a) Name the gas that diffuses from the alveoli into the blood, and the gas that diffuses from the blood into the alveoli. [2] (b) Describe how oxygen moves from the air in an alveolus into the blood. Refer to diffusion and a concentration gradient. [2] (c) Give one feature of an alveolus that makes it well adapted for efficient gas exchange, and explain how that feature helps. [2] (d) During vigorous exercise, a person's breathing rate and depth of breathing both increase. Explain how these changes help to maintain a high rate of gas exchange in the alveoli during exercise. [3]

  (Total for Question A4 is 9 marks)
• 5

  Question A5 (9 marks)

  A person is infected with a bacterium that causes a throat infection. (a) State whether antibiotics or antiviral drugs should be used to treat this infection, and give a reason. [2] (b) Describe how white blood cells defend the body against this bacterium. Include the role of phagocytes and of antibodies. [4] (c) Explain what is meant by antibiotic resistance and describe how the overuse of antibiotics can lead to resistant bacteria becoming more common. [3]

  (Total for Question A5 is 9 marks)

Section B

Answer all questions. Extended answers should use evidence and key terms.

• 1

  Question B1 (9 marks)

  Blood glucose concentration is controlled by hormones released from the pancreas. (a) Name the hormone released by the pancreas when blood glucose concentration is too high, and name the organ that responds to it. [2] (b) Describe what happens to blood glucose concentration after a meal high in carbohydrate, and explain how the body brings it back to normal. Use appropriate key terms in your answer. [4] (c) Type 1 diabetes is caused by the pancreas failing to produce enough of the hormone in part (a). Explain why a person with untreated Type 1 diabetes has a very high blood glucose concentration after eating, and state one way it is commonly treated. [3]

  (Total for Question B1 is 9 marks)
• 2

  Question B2 (9 marks)

  In a species of mouse, coat colour is controlled by a single gene. The allele for brown coat (B) is dominant to the allele for white coat (b). (a) Define the terms 'dominant allele' and 'genotype'. [2] (b) A heterozygous brown mouse (Bb) is crossed with a white mouse (bb). Draw a genetic (Punnett) cross to show the possible genotypes of the offspring, and state the expected ratio of brown to white offspring. [4] (c) Two brown mice are bred together and produce some white offspring. Explain, using genetics key terms, what this tells you about the genotypes of the two brown parent mice. [3]

  (Total for Question B2 is 9 marks)
• 3

  Question B3 (9 marks)

  A woodland ecosystem contains oak trees, caterpillars that eat oak leaves, blue tits that eat caterpillars, and sparrowhawks that eat blue tits. (a) Construct the food chain for this woodland and identify the producer and one secondary consumer. [3] (b) Explain why there is much less energy available to the sparrowhawks than to the caterpillars. Use appropriate key terms about energy transfer. [3] (c) Describe how carbon from the oak trees is returned to the atmosphere as carbon dioxide. Refer to two different processes. [3]

  (Total for Question B3 is 9 marks)
• 4

  Question B4 (9 marks)

  When a person touches a sharp pin, they pull their hand away very quickly without thinking. This is a reflex action. (a) Explain the survival advantage of a reflex action being rapid and automatic. [2] (b) Name, in the correct order, the parts of the nervous system that carry the impulse in this reflex, from the pin touching the skin to the hand pulling away. [2] (c) Explain how the impulse is passed from one neurone to the next across a synapse. [2] (d) A scientist measures the reaction time for this reflex and for a voluntary response to the same stimulus. The reflex is much faster than the voluntary response. Explain why the reflex action is faster than a voluntary response. [3]

  (Total for Question B4 is 9 marks)
• 5

  Question B5 (9 marks)

  A population of beetles lives on a light-coloured tree bark. Most beetles are pale, but a few are dark. A species of bird hunts the beetles by sight. Over many years, air pollution darkens the tree bark. (a) Define natural selection. [2] (b) Explain, using the theory of natural selection, how the dark beetles could become the most common type in the population after the bark darkens. Use appropriate key terms. [4] (c) Fossils of beetles like these can be found in rock layers of different ages. Explain how fossils provide evidence for evolution by natural selection. [3]

  (Total for Question B5 is 9 marks)