At each lamp distance, a student records three gas volumes over 4 minutes. A leak is confirmed during the third measurement at 20 cm, so that measurement is excluded.
The table shows the results.
Table
| Distance in cm | First volume in cm3\text{cm}^3cm3 | Second volume in cm3\text{cm}^3cm3 | Third volume in cm3\text{cm}^3cm3 |
|---|---|---|---|
| 20 | 8.0 | 8.4 | 3.2 |
| 40 | 2.0 | 2.2 | 2.1 |
Using the valid measurements, what is the difference between the mean rates at the two distances?
1.525 cm3/min1.525\ \text{cm}^3\text{/min}1.525 cm3/min
2.050 cm3/min2.050\ \text{cm}^3\text{/min}2.050 cm3/min
3.900 cm3/min3.900\ \text{cm}^3\text{/min}3.900 cm3/min
6.100 cm3/min6.100\ \text{cm}^3\text{/min}6.100 cm3/min
44 exam-style questions on Edexcel GCSE Biology 6.1 Photosynthesis, covering 6.1.1 Photosynthetic organisms as producers, 6.1.2a Limiting factors on the rate of photosynthesis, 6.1.2b Interactions of limiting factors on photosynthesis, and 6.1.3 Inverse square law and light intensity. Each one has a worked solution and a mark scheme showing where the marks go.