Answer on paper first, then reveal the mark scheme one mark at a time.
(a) Complete the word equation for photosynthesis.
carbon dioxide + ............ → glucose + ............ [2]
(b) Name the mineral ion that a plant needs to make chlorophyll. [1]
A student placed a piece of pondweed in water and counted the number of bubbles of gas released per minute with a lamp at different distances.
| Distance of lamp / cm | Number of bubbles per minute |
|---|---|
| 10 | 48 |
| 20 | 30 |
| 30 | 17 |
| 40 | 9 |
| 50 | 5 |
(a) Describe the relationship shown by the results. [1]
(b) Explain the relationship. [2]
(c) Suggest why counting bubbles may not give an accurate measurement of the rate of photosynthesis. [1]
(d) Give one variable the student should control and describe how to control it. [1]
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