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Biology questions, chapter 5
Nama / NameKelas / ClassTarikh / Date

Response in Plants

45 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.

Section A: objective questions

12 marks
Choose the best answer for each question.
1

Question 1

Which statement describes tropism?
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B
Tropism is the response of a plant part such as the root or shoot towards or away from a stimulus. Option A describes a nastic response.
For the teacher: Remembering, low difficulty, standard 5.1
Textbook p. 98
2

Question 2

A root grows towards a source of water in the soil. This response is
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C
The stimulus is water, so the response is hydrotropism. The root grows towards it, so it is positive.
For the teacher: Remembering, low difficulty, standard 5.1
Textbook p. 100
3

Question 3

The leaves of a river tamarind plant close at night. This is an example of
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D
Nyctinasty is a response to the onset of darkness (a circadian rhythm). Photonasty is a response to light, e.g. opening of petals.
For the teacher: Understanding, low difficulty, standard 5.1
Textbook p. 102
4

Question 4

Which phytohormone closes the stomata during a drought?
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A
Abscisic acid induces stomatal closing in drought, and also seed dormancy.
For the teacher: Remembering, low difficulty, standard 5.2
Textbook p. 103
5

Question 5

A Venus flytrap shuts its leaves when an insect touches the hairs inside. Which statement is correct?
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C
The trap closes the same way whichever hair is touched, so the direction is independent of the stimulus: a nastic response (thigmonasty).
For the teacher: Understanding, medium difficulty, standard 5.1
Textbook p. 102
6

Question 6

Diagram 1 shows seven coleoptile treatments in one-sided light. Seedling 3, counting from the left, has its tip covered with an opaque cover. What is observed on seedling 3 after two to three days?
Textbook figure of seven coleoptile treatments before and after one-sided light
Diagram 1 (textbook Figure 5.6)
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B
With the tip covered, the tip cannot detect the light, so auxin stays evenly distributed and the coleoptile grows upwards.
For the teacher: Applying, medium difficulty, standard 5.2
Textbook p. 105
7

Question 7

Why does a shoot bend towards a window?
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D
Auxin moves away from the light. The higher concentration on the shaded side makes those cells elongate more, so the shoot bends towards the light.
For the teacher: Understanding, medium difficulty, standard 5.2
Textbook p. 105
8

Question 8

Diagram 2 shows the effect of auxin concentration on the growth of a shoot and a root. What is the effect of an auxin concentration of 1 mg dm⁻³?
Graph of growth response against auxin concentration for shoot and root
Diagram 2 (textbook Figure 5.5)
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A
At 1 mg dm⁻³ the shoot curve is high above zero (stimulation) while the root curve is below zero (inhibition).
For the teacher: Analysing, high difficulty, standard 5.2
Textbook p. 104
9

Question 9

An unripe mango is kept in a paper bag together with a ripe banana. The mango ripens faster because the banana releases
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B
Ripe fruit gives off ethylene gas, which stimulates ripening.
For the teacher: Applying, low difficulty, standard 5.3
Textbook p. 108
10

Question 10

Which is a characteristic of tropism but not of nastic responses?
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C
In tropism the direction of growth depends on the direction of the stimulus. Tropism is slow, not quick.
For the teacher: Understanding, low difficulty, standard 5.1
Textbook p. 99
11

Question 11

A farmer has dwarf mutant plants and wants them to grow to normal height and produce larger grapes. Which phytohormone should he use?
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D
Gibberellin makes dwarf mutants grow to normal height and is used to produce larger grapes.
For the teacher: Applying, medium difficulty, standard 5.3
Textbook p. 107
12

Question 12

Tulip flowers open when the room is warm and close when it is cool. Which is correct?
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A
Temperature is the stimulus, and the opening and closing is independent of direction, so it is thermonasty.
For the teacher: Analysing, medium difficulty, standard 5.1
Textbook p. 102

Section B: structured questions

33 marks
Answer all questions. Write your answers in the spaces provided.
13

Question 13

Choose the type of tropism for each stimulus.
[1 mark] (a)Gravity
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Geotropism
[1 mark] (b)Touch
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Thigmotropism
[1 mark] (c)Mineral salts in the soil
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Chemotropism
[1 mark] (d)Light
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Phototropism
For the teacher: Remembering, low difficulty, standard 5.1
Textbook p. 99
14

Question 14

A student noticed that the leaves of a mimosa plant fold within seconds when touched, but a tendril takes hours to coil around a stick.
[1 mark] (a)Name the response of the mimosa leaves.
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Tick each point you got.
[1 mark] (b)Name the response of the tendril.
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[2 marks] (c)State two differences between the two types of response.
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Any 2 points
Tick each point you got.
For the teacher: Understanding, low difficulty, standard 5.1
Textbook p. 102
15

Question 15

Diagram 3 shows three experiments on coleoptiles.
Three coleoptile experiments with the tip cut off, agar blocks and off-centre agar
Diagram 3 (textbook Figure 5.4)
[1 mark] (a)Name the phytohormone made at the coleoptile tip.
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Tick each point you got.
[1 mark] (b)Why is no growth observed in Experiment I after the tip is removed?
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Tick each point you got.
[2 marks] (c)Explain why the coleoptile in Experiment III curves.
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[1 mark] (d)Why does the coleoptile in Experiment II grow straight upwards?
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For the teacher: Analysing, medium difficulty, standard 5.2
Textbook p. 104
16

Question 16

A bean seed germinates while lying on its side in the soil.
[2 marks] (a)State the direction in which the root grows and name the response.
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Tick each point you got.
[2 marks] (b)Explain how auxin makes the shoot bend upwards.
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[2 marks] (c)Explain why the same high auxin concentration makes the root bend downwards.
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For the teacher: Applying, medium difficulty, standard 5.2
Textbook p. 106
17

Question 17

A student grew oat seedlings in one-sided light. Seedling P had its tip covered with an opaque cover. Seedling Q had its tip separated from the rest of the coleoptile by a mica sheet. Seedling R was untreated.
[1 mark] (a)State the response of seedling R.
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Tick each point you got.
[2 marks] (b)Predict the growth of seedling P and explain.
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[1 mark] (c)Seedling Q does not grow. Explain.
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Tick each point you got.
For the teacher: Analysing, high difficulty, standard 5.2
Textbook p. 105
18

Question 18

A fruit farm sells key limes. Mrs Faridah put an unripe key lime and a ripe banana in a closed container at room temperature.
[1 mark] (a)Justify her decision to put both fruits in the same closed container.
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Tick each point you got.
[2 marks] (b)What would happen if the container were kept in a refrigerator? Explain.
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[2 marks] (c)Suggest a method to delay ripening of fruits during export and justify it.
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For the teacher: Evaluating, medium difficulty, standard 5.3
Textbook p. 111
19

Question 19

Plan an experiment to find out whether ethylene speeds up the ripening of tomatoes. You are given unripe tomatoes, a ripe banana and paper bags.
[2 marks] (a)State the manipulated variable and the responding variable.
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Tick each point you got.
[1 mark] (b)State one constant variable.
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Any 1 points
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[2 marks] (c)Describe the procedure.
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Tick each point you got.
For the teacher: Creating, medium difficulty, standard 5.3
Textbook p. 108