A shallow salt lake contains no plants or algae. Scientists investigate whether a species of bacterium can begin a food chain in the lake.
Equal samples of the bacterium are placed in containers with water, mineral ions and excess carbon dioxide, but no organic material. One sample is kept in the light and the other is kept in the dark.
The table shows the mean dry mass of each sample.
| Sample | Mean dry mass at the start in g | Mean dry mass after 6 days in g |
|---|---|---|
| Kept in the light | 0.20 | 0.46 |
| Kept in the dark | 0.20 | 0.15 |
Explain how these results support the conclusion that this bacterium can begin a food chain, and how energy from the light can eventually reach fish in the lake.
117 exam-style questions on OCR GCSE Biology 1.4 Photosynthesis, covering 1.4.1 Photosynthesisers as biomass producers, 1.4.2 Factors affecting the rate of photosynthesis, and 1.4.3 Limiting factors in photosynthesis. Each one has a worked solution and a mark scheme showing where the marks go.