6 exam-style questions with full mark schemes and model answers. Write your own answer and the AI examiner marks it against the mark scheme.
A scientist studies two cells under a microscope: a single-celled bacterium living in pond water, and a palisade mesophyll cell taken from a leaf of pondweed.
Compare the structures of the bacterial cell and the plant palisade cell. In your answer you should describe both similarities and differences, refer to named sub-cellular structures, and explain how features of the palisade cell suit its function. (6 marks)
A student views an onion epidermis cell with a light microscope. In the image, one cell measures 50 mm long, and the student is told the real (actual) length of the cell is 0.1 mm.
(Remember: 1 mm=1000μm.)
(a) Calculate the magnification of the image. Show your working. (2 marks)
(b) Using the same microscope at this magnification, a chloroplast in a nearby plant cell appears 4 mm wide in the image. Calculate the real width of the chloroplast, in micrometres (μm). Show your working. (2 marks)
A student investigates how temperature affects the activity of the enzyme amylase, which breaks down starch. They measure the rate of reaction at five temperatures. The results are shown below.
| Temperature (°C) | Rate of reaction (arbitrary units) |
|---|---|
| 10 | 8 |
| 20 | 16 |
| 30 | 32 |
| 40 | 50 |
| 50 | 6 |
(a) Describe and explain the pattern shown by the results between 10 °C and 40 °C. (2 marks)
(b) Explain, in terms of the enzyme molecule, why the rate is so low at 50 °C. (1 mark)
Plants make glucose by photosynthesis and release energy from glucose by respiration.
(a) Write the word equation for photosynthesis. (1 mark)
(b) Write the balanced symbol equation for aerobic respiration. (2 marks)
A grower measures the rate of photosynthesis of a tomato plant as the light intensity increases. The rate rises steadily at first, then levels off and stays constant even when the light intensity keeps increasing.
(a) Name one factor, other than light intensity, that could be limiting the rate of photosynthesis once it has levelled off. (1 mark)
(b) Explain what is meant by a limiting factor, and use this idea to explain the shape of the grower's results. (1 mark)
When yeast respires anaerobically, it carries out fermentation, which is used in brewing and bread-making.
State the word equation for anaerobic respiration in yeast. (1 mark)