Students investigated the response of plant shoots to one-sided light - AQA - GCSE Biology - Question 9 - 2022 - Paper 1
Question 9
Students investigated the response of plant shoots to one-sided light.
Figure 13 shows how the students set up three experiments.
Experiment A
Light
Ink marks
12 h... show full transcript
Worked Solution & Example Answer:Students investigated the response of plant shoots to one-sided light - AQA - GCSE Biology - Question 9 - 2022 - Paper 1
Step 1
Suggest two control variables the students should have used in their investigation.
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Answer
Same amount of water
Same temperature
Step 2
Describe how experiment B and experiment C acted as controls for the investigation.
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Answer
Experiment B acts as a control by demonstrating the effects of light without any exposure, showing that light is essential for the response. Experiment C shows the effect of light from multiple sources, ensuring that the response measured in Experiment A due to one-sided light is valid.
Step 3
Give two conclusions that the students could make from the ink marks on the shoot in experiment A.
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The shoot bends towards the light source indicating positive phototropism.
Growth is more significant on the side of the shoot that is furthest from the light, which causes the bending.
Step 4
Name the type of response shown by the seedling in experiment A.
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Answer
Phototropism
Step 5
Describe the evidence from Figure 14 which supports the hypothesis.
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The evidence shows that there is more auxin in the side of the agar jelly that was placed away from the light (blocks D and F), confirming that auxin moves to the side furthest from the light source.
Step 6
Give the evidence from Figure 14 that shows that auxin is not broken down by light.
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In blocks E and G, the mass of auxin is the same despite being in conditions exposed to light. This indicates that light does not break down auxin.
