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3.34 Geotropic and phototropic responses
Exam question
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Describe the geotropic responses of roots and shoots.
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Total for this question: 2 marks
3.34 Geotropic and phototropic responses
Exam question
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Describe the phototropic responses of roots and shoots.
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Total for this question: 2 marks
3.34 Geotropic and phototropic responses
Exam question
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Describe how a clinostat can be used to show that roots respond to gravity.
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Total for this question: 3 marks
3.34 Geotropic and phototropic responses
Exam question
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Explain why the root on the rotating clinostat grows straight.
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Total for this question: 2 marks
3.34 Geotropic and phototropic responses
Exam question
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Illustrative data.
| Time / hours | Curvature / degrees |
|---|---|
| 0 | 0 |
| 4 | 15 |
| 8 | 38 |
| 12 | 62 |
| 16 | 80 |
| 20 | 88 |
Plot a graph of root curvature against time. Join your points with straight lines using a ruler.
(5)Graph skills: SLAPUK and choosing a scale
Write your answer, then press Show model answer and tick each mark point your answer makes. Your answer is not saved.
Total for this question: 5 marks
3.34 Geotropic and phototropic responses
Exam question
Mark points shown after marking
| Time / hours | Curvature / degrees |
|---|---|
| 0 | 0 |
| 4 | 15 |
| 8 | 38 |
| 12 | 62 |
| 16 | 80 |
| 20 | 88 |
Calculate the mean rate of curvature between 4 and 12 hours.
(2)Total for this question: 2 marks
3.34 Geotropic and phototropic responses
Exam question
Mark points shown after marking
| Time / hours | Curvature / degrees |
|---|---|
| 0 | 0 |
| 4 | 15 |
| 8 | 38 |
| 12 | 62 |
| 16 | 80 |
| 20 | 88 |
Suggest why the curvature levels off at about 90°.
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Total for this question: 2 marks
3.34 Geotropic and phototropic responses
Exam question
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Explain why the seeds were kept in the dark in this experiment.
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Total for this question: 2 marks
3.34 Geotropic and phototropic responses
Exam question
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A seedling is placed in total darkness on its side. In which direction does the shoot grow?
(1)Total for this question: 1 mark
3.34 Geotropic and phototropic responses
Exam question
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Suggest why shoots growing from seeds buried in the soil grow upwards.
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Total for this question: 2 marks
Plan it with CORMMSS: Design an investigation (Logic Lab).
3.34 Geotropic and phototropic responses
Exam question
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Link: practise planning on /subjects/igcse-biology/logic-lab/design-an-investigation.
Design an investigation to find out how light intensity affects the phototropic response of cress seedlings.
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Total for this question: 6 marks
3.34 Geotropic and phototropic responses
Exam question
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Explain why seedlings grown in the dark are tall, thin and yellow.
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Total for this question: 2 marks
3.34 Geotropic and phototropic responses
Exam question
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Compare the responses of a shoot and a root to light from one side.
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Total for this question: 2 marks
3.34 Geotropic and phototropic responses
Exam question
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Explain why it is an advantage for roots to be negatively phototropic.
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Total for this question: 2 marks
