This figure shows a vertical farm shelf with red and blue LED lamps above basil plants. A student measured oxygen concentration in the air around the plants...
Question 1 Report
This figure shows a vertical farm shelf with red and blue LED lamps above basil plants. A student measured oxygen concentration in the air around the plants. Table 1 gives measurements after 30 minutes.
| lamp setting | oxygen change / % |
|---|---|
| red only | +0.4 |
| red and blue | +0.9 |
(a) Use Table 1 to state the lamp setting with the larger oxygen increase. [1]
(b) Suggest why oxygen concentration rose around the plants. [1]
(c) Describe one use of glucose made by basil cells. [1]
(d) Suggest why the farm controls lamp colour as well as lamp brightness. [1]
The diagram shows a school laboratory test for oxygen using a glowing splint. The student collected gas from a water plant under a funnel. Table 1 gives repeated results from three identical plants.
| plant | gas volume in 15 min / cm3 |
|---|---|
| 1 | 8.1 |
| 2 | 7.9 |
| 3 | 8.0 |
(a) Name the gas that relights a glowing splint. [1]
(b) Use Table 1 to calculate the mean gas volume. [1]
(c) Describe why repeating the measurement improves the investigation. [1]
(d) Suggest why the water temperature should be monitored. [1]
Answer Details
LED lamps and basil
- (a) The combined red and blue lamp setting produced the larger oxygen increase, \(+0.9\%\). [1]
- (b) Oxygen concentration rose because photosynthesis released oxygen. [1]
- (c) Glucose can be used in respiration, to make cellulose, or to make other substances for growth. [1]
- (d) Lamp colour is controlled because chlorophyll absorbs different wavelengths of light differently. [1]
Testing collected gas
- (a) The gas that relights a glowing splint is oxygen. [1]
- (b) \[\frac{8.1+7.9+8.0}{3}=8.0\text{ cm}^3\] The mean gas volume is \(8.0\text{ cm}^3\). [1]
- (c) Repeating measurements allows a mean to be calculated and helps identify anomalous results. [1]
- (d) Water temperature should be monitored because temperature affects enzyme-controlled photosynthesis. [1]
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