Paper 4 style practice paper: Structured questions (Extended) — question paper

Section A: Structured questions[40 marks]

Answer all questions in the spaces provided.

1. 1

   Diagrams show three cells: a leaf palisade cell, a human skin cell and a bacterial cell.

   1. (a)

      Name one structure visible in the palisade cell that is missing from the skin cell, and state its function.

      [2]
   2. (b)

      Name two structures that the bacterial cell shares with the other two cells.

      [2]
   3. (c)

      The palisade cell image is 12 mm wide at ×600 magnification. Calculate the actual width of the cell in mm.

      [2]
   4. (d)

      State the term for the level of organisation that a group of similar cells working together represents.

      [2]
2. 2

   The enzyme amylase digests starch to maltose. A student investigates amylase activity at different pH values, keeping temperature and enzyme concentration constant.

   1. (a)

      State the variable that was changed and two variables that were controlled.

      [3]
   2. (b)

      Describe how iodine solution could be used to measure how quickly the starch is digested.

      [3]
   3. (c)

      Predict and explain the amylase activity at pH 2 compared with its optimum around pH 7.

      [4]
3. 3

   A student uses a potometer to investigate water uptake by a leafy shoot. The distance the air–water boundary moves is recorded over five minutes at different air humidities.

   1. (a)

      Explain why water uptake by the shoot is an estimate of the rate of transpiration.

      [2]
   2. (b)

      Predict and explain the effect of increasing the humidity of the air around the shoot.

      [3]
   3. (c)

      State two other variables the student should control.

      [2]
   4. (d)

      The boundary moves 45 mm in 5 minutes; the capillary tube has a cross-sectional area of 2.0 mm². Calculate the rate of water uptake in mm³ per minute.

      [3]
4. 4

   The mammalian heart and circulation.

   1. (a)

      Explain why the wall of the left ventricle is thicker than the wall of the right ventricle.

      [3]
   2. (b)

      Describe the path of a red blood cell from the vena cava to the aorta, naming each chamber and vessel in order.

      [4]
   3. (c)

      State the function of platelets and describe, using fibrinogen and fibrin, how a clot forms.

      [5]

Section B: Structured questions[40 marks]

Answer all questions in the spaces provided.

1. 5

   In mice, the allele for black fur (B) is dominant to the allele for brown fur (b).

   1. (a)

      Complete a Punnett square for a cross between two heterozygous black mice (Bb × Bb).

      [2]
   2. (b)

      State the genotypic ratio and the phenotypic ratio of the offspring.

      [2]
   3. (c)

      A black mouse was crossed with a brown mouse. Some of the offspring were brown. Deduce the genotype of the black parent, explaining your reasoning.

      [3]
   4. (d)

      Explain how the sex of a mouse offspring is determined, and state the expected ratio.

      [3]
   5. (e)

      Explain why the mouse’s phenotype for fur colour cannot always be used to deduce its genotype.

      [2]
2. 6

   Gas exchange and respiration during exercise.

   1. (a)

      Describe two features of the alveoli that make them efficient gas exchange surfaces.

      [2]
   2. (b)

      Describe how expired air differs from inspired air, and state the test that demonstrates the difference.

      [3]
   3. (c)

      After a sprint, an athlete continues to breathe deeply and quickly for several minutes. Explain why. (Extended)

      [5]
3. 7

   A lake ecosystem receives run-off from farmland.

   1. (a)

      Define the terms population and community.

      [2]
   2. (b)

      Construct a food chain with four trophic levels for this lake, naming the trophic level of each organism.

      [4]
   3. (c)

      Explain the process of eutrophication and its effect on the lake’s fish. (Extended)

      [4]
4. 8

   Insulin for people with diabetes is produced by genetically modified bacteria.

   1. (a)

      State two reasons why bacteria are used in this process.

      [2]
   2. (b)

      Outline how the human insulin gene is inserted into a bacterial plasmid. (Extended)

      [4]
   3. (c)

      Describe what happens to the bacteria after the recombinant plasmids are inserted.

      [2]