Plant Hormones Practice Questions

Question 1

3 marks

A student grew a bean seedling in a pot on a windowsill. After one week the shoot was bent towards the window.

(a)

What is meant by the term phototropism?

/ 1

(b)

Complete the table to show how the shoot and the root of the seedling respond to gravity.

Part of seedling	Direction of growth in response to gravity
Shoot
Root

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Question 2

4 marks

A gardener takes cuttings from a lavender plant. She dips the cut end of each stem into a rooting powder before planting it in compost.

(a)

Name the type of plant hormone found in rooting powder.

/ 1

(b)

Explain why using rooting powder helps the cutting to grow into a new plant.

/ 1

(c)

Give two other ways that auxins are used in agriculture or horticulture.

/ 2

Question 3

3 marks

Tomatoes are grown in Spain and transported to the UK by lorry. The tomatoes are picked while they are still green and unripe.

(a)

Name the plant hormone used in the food industry to ripen fruit.

/ 1

(b)

Give one other process in plants that is controlled by this hormone.

/ 1

(c)

Suggest one advantage to the supermarket of picking the tomatoes when they are unripe and then treating them with this hormone just before they go on sale.

/ 1

Question 0

6 marks

A student germinated broad bean seeds. She pinned one newly germinated seedling on its side onto damp cotton wool and sealed it inside a box that let no light in.

After 4 days the seedling looked like this.

(a)

Give one reason why the seedling was kept in a box that let no light in.

/ 1

(b)

Explain, in terms of auxin, why the root grew downwards.

/ 3

(c)

The shoot of the same seedling grew upwards. Explain why.

/ 2

Question 0

5 marks

Students grew cress seedlings in three different light conditions. All other variables were kept the same. After 5 days they measured the length of the shoot of five seedlings from each condition.

Condition	Shoot length in mm					Mean shoot length in mm
	1	2	3	4	5
Light from all sides	22	25	24	23	26	24.0
Light from one side only	31	29	33	30	32	31.0
No light	45	48	42	47	43

(a)

Calculate the mean shoot length for the seedlings grown in no light.

Give your answer to 1 decimal place.

/ 2

(b)

Describe the trend shown by the mean results.

/ 1

(c)

Suggest why the seedlings grown in no light had the longest shoots.

/ 1

(d)

Give one reason why the students measured five seedlings in each condition and calculated a mean.

/ 1

Question 0

6 marks

A class is asked to investigate the effect of the direction of light on the growth of newly germinated seedlings.

(a)

Describe a method the class could use.

In your answer you should include the control variables that must be kept the same.

/ 4

(b)

As well as length measurements, the class was told to record their results as careful, labelled biological drawings.

Give two advantages of recording the results as labelled drawings.

/ 2

Question 0

4 marks

A scientist investigated where a shoot detects light. She used four young oat shoots of the same age and height. Each shoot was given light from one side only for 2 days. All other variables were kept the same.

Shoot	Treatment	Result after 2 days
A	none	bent towards the light
B	tip cut off	grew straight, very little growth in height
C	opaque (black) cap placed over the tip	grew straight upwards
D	transparent cap placed over the tip	bent towards the light

(a)

Explain why shoot D was included in the investigation.

/ 1

(b)

Explain the result for shoot C.

/ 2

(c)

What does the result for shoot B suggest about where auxin is produced in the shoot?

/ 1

Question 0

4 marks

Some seeds are dormant. Dormant seeds will not germinate even when they are given water, oxygen and a suitable temperature. A seed company treats packets of wildflower seeds with a plant hormone before selling them.

(a)

Name the plant hormone that is important in starting seed germination.

/ 1

(b)

Explain one advantage to a gardener of buying seeds that have been treated with this hormone.

/ 2

(c)

Give one other use of this hormone in horticulture.

/ 1

Question 0

6 marks

A farmer sprays a selective weed killer on a field of wheat. The weed killer contains synthetic auxins. It kills broad-leaved weeds such as poppies and thistles, but does not harm the wheat.

Evaluate the use of this weed killer on the farm.

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Question 0

5 marks

A scientist cut the tips off young shoots. She placed a small block of agar containing auxin on the left-hand side of the cut surface of each shoot, as shown in the diagram. The shoots were then kept in a dark cupboard for 24 hours.

The experiment was repeated using agar blocks containing different concentrations of auxin. The scientist measured the angle the shoots had bent through.

Concentration of auxin in agar block in arbitrary units	Mean angle of bending in degrees
0	0
5	8
10	15
20	28
40	30

(a)

Give one reason why the shoots were kept in the dark.

/ 1

(b)

All the shoots that bent, bent towards the right. Explain why.

/ 2

(c)

Describe what the results show about the effect of auxin concentration on the bending of the shoots.

/ 2

Cell Biology

Organisation

Infection & Response

Bioenergetics

Homeostasis & Response

Inheritance, Variation & Evolution

Ecology

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