1 markA group of students wanted to set up an experiment to investigate plant growth.
They attached a plant pot to a clinostat and placed it in a dark room as shown in the image below:
Which of the following images would show the expected result of this experiment after two days?
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1 markA group of students set up an experiment to investigate growth responses in plants.
In one of the experiments, they placed a plant shoot in a box with a small window allowing light to fall on one side of the shoot only.
Which of the following options correctly describes and explains what happened in the student’s experiment?
|
response |
cause |
effect |
|
|
A |
positive phototropism | more auxin on side of shoot exposed to light | slower growth on shaded side of shoot |
|
B |
positive phototropism | more auxin on shaded side of shoot | slower growth on side of shoot exposed to light |
|
C |
negative gravitropism | even distribution of auxins | equal rates of growth |
|
D |
positive phototropism | less auxin on shaded side of shoot | faster growth on side of shoot exposed to light |
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What is the role of auxin in the control of phototropism in the shoot of a plant?
Auxin is only made on the shaded side of the shoot. This causes the cells on the shaded side to grow longer.
More auxin is distributed on the shaded side of the shoot. This causes the cells on the shaded side to grow longer.
The light side of the shoot contains more auxin and so grows less. This causes the shoot to bend towards the light.
The light side of the shoot contains more auxin. This stimulates cell division and so the light side of the shoot grows more.
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