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GCSEBiology: Combined ScienceEdexcelExam Questions6. Plant Structures & their Functions6.4 Plant Hormones

Plant Hormones (Edexcel GCSE Biology: Combined Science)

Exam Questions

18 mins3 questions
1a
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Complete the sentence.

Choose the answer from the box

Towards         Decreases         Phototropism          Grow          Away from          Shade         Water         

Away from light     Geotropism         Towards light          Increases     Light Energy


__________ is beneficial for plants because it means that plant shoots can grow __________  __________ . This allows chloroplasts to absorb more __________ which __________ photosynthesis.

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1b
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Figure 1 shows different parts of the plant and a number of responses.

part-of-plants-responce

Figure 1

Draw one line from each plant part to the correct response.

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2a
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Name the plant hormone responsible for both phototropism and gravitropism.

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2b
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What effect do auxins have on plants?

  ☐ A Promotes growth in both the shoot and the root.
  ☐ B Inhibits growth in both the shoot and the root.
  ☐ C Promotes growth in the shoot but inhibits growth in the root.
  ☐ D Inhibits growth in the shoot and promotes growth in the root.

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2c
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A group of students set up an experiment to investigate plant growth.

They attached a plant pot to a machine called a clinostat so that it could be rotated slowly on its side as shown in Figure 1. The apparatus was then placed in a darkened room.

14--image-6---plant-1

Figure 1

Which of the following images would show the expected result of this experiment after two days?

14--image-7---plant-growth-1

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2d
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Figure 2 represents a plant shoot growing, it is illuminated from the side.

q6_9-3_growth_in_plants_ib_biology_hl_mcqq6_9-3_growth_in_plants_ib_biology_hl_mcq-1

Figure 2

Which of the following images best represents how auxins will start to accumulate in the shoot tip in response to light?

plants

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3a
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A group of students wanted to investigate geotropism in bean seedling roots.

The set-up of their experiment is shown in the diagram below.

gravitropism-4agravitropism-4a

The students used the following method:

    • Measure the starting length of the roots of 5 bean seedlings
    • Pin the 5 bean seedlings to a cork mat as shown in Apparatus A
    • Place Apparatus A in a dark cupboard for 3 days
    • After 3 days, measure the length of the root in each seedling and make a drawing of each seedling

The students then set up Apparatus B in exactly the same way as Apparatus A, but used a clinostat to rotate the cork board constantly.

Explain the purpose of Apparatus B.

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3b
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The seedlings in the experiment in part (a) were placed in a dark room to remove the effect of light. This is a control variable.

State why this stage is necessary.

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3c
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The diagram below shows the appearance of the seedlings at the end of the 3 days.

seedlings-4d

Explain the appearance of the seedlings in the diagram.

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3d
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The students carried out their experiment using 10 bean seedlings split across two sets of apparatus; Apparatus A and Apparatus B (the control).

The results of the student’s investigation are shown in the table below.

  Apparatus A Apparatus B
Seedling number 1 2 3 4 5 1 2 3 4 5
Length of seedling on day 0 / mm 33 34 36 40 42 29 30 34 31 32
Length of seedling on day 2 / mm 45 35 48 53 56 41 43 44 44 43
Change in length / mm 12 1 12 13 14 12 13 10 13 11
Mean change in length / mm 12.75  

Calculate the mean change in length for the bean seedlings in Apparatus B.

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