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.
Learn this properly: Eukaryotic and Prokaryotic CellsA microbiologist examines two cells from a sample: a bacterial cell (a prokaryote) and a palisade cell taken from a plant leaf (a eukaryote).
Compare the structures of the bacterial cell and the plant palisade cell. In your answer you should describe both similarities and differences, and refer to named sub-cellular structures. (6 marks)
A student uses a light microscope to view a plant cell. In the image, one chloroplast measures 12 mm across. The student is told that the real (actual) width of the chloroplast is 6 μm.
(Remember: 1 mm = 1000 μm.)
(a) Calculate the magnification of the image. Show your working. (3 marks)
(b) Using a different microscope, an image is recorded at a magnification of ×800. In this image, a mitochondrion appears 2 mm long. Calculate the real length of the mitochondrion, in micrometres (μm). (1 mark)
The enzyme lipase breaks down lipid (fat) molecules into fatty acids and glycerol. Lipase will break down lipids but it will not break down starch.
(a) Enzymes are described as biological catalysts. State what is meant by the term catalyst. (1 mark)
(b) Explain, in terms of the enzyme's active site, why lipase breaks down lipids but not starch. (2 marks)
In Core Practical 2, a student investigated osmosis using cylinders cut from a potato. Five cylinders were each placed in a different concentration of sucrose solution for 24 hours. The initial and final masses were recorded.
| Sucrose concentration / mol dm⁻³ | Initial mass / g | Final mass / g |
|---|---|---|
| 0.0 | 2.50 | 2.80 |
| 0.2 | 2.40 | 2.52 |
| 0.4 | 2.60 | 2.60 |
| 0.6 | 2.50 | 2.30 |
| 0.8 | 2.45 | 2.06 |
(a) Calculate the percentage change in mass of the potato cylinder in the 0.0 mol dm⁻³ solution. Show your working. (2 marks)
(b) State what the data tell you about the internal concentration of the potato cells, and explain how the data show this. (1 mark)
Root hair cells absorb mineral ions, such as nitrate ions, from the soil. The concentration of these ions is usually higher inside the root hair cell than in the surrounding soil water.
Explain why active transport, rather than diffusion, is needed for the root hair cell to absorb these mineral ions. (2 marks)
During the cell cycle, body cells divide by mitosis.
Name the type of daughter cells (in terms of their chromosome number and genetic make-up) that are produced by mitosis. (1 mark)