[Maximum number: 8]

Plants are sensitive to light.

(a)

Fig. 1.1 shows a sequence of diagrams for two young plant seedlings. The seedlings were first grown in pots with light from all directions and then placed into boxes.
- Seedling A was placed in a box with light entering from one side only.
- Seedling B was placed in a box with no light.

Fig. 1.1

Complete Fig. 1.1 by drawing seedling A and seedling B, in the boxes, to show the expected direction of their growth after one week.

[ 2 ]

(b)

Plants are also sensitive to gravity.

[ 6 ]

(i)

Explain the role of plant hormones in gravitropism.

[ 4 ]

(ii)

Gravitropism enables plants to survive in their environment.

Explain how gravitropism enables a plant to survive.

[ 2 ]

[Maximum number: 9]

Fig. 2.1 is a flow chart that shows the events that occur as light travels through the eye.

Fig. 2.1

(a)

A plant, Arabidopsis thaliana, was placed on its side in the dark. Fig. 2.2 is a series of drawings made of the plant, over seven days, as it responded to a change in its surroundings.

Fig. 2.2

[ 9 ]

(i)

State the stimulus to which the plant responded.

[ 1 ]

(ii)

Name the growth response shown by the plant.

[ 2 ]

(iii)

Explain the advantage to plants of the growth response shown in Fig. 2.2.

[ 2 ]

(iv)

Auxins control the growth responses of seedlings.

Explain how auxins control the growth response of A. thaliana, shown in Fig. 2.2.

[ 4 ]

(a)

Fig. 3.1 shows a growing plant. The plant is growing in the dark.

Fig. 3.1

[ 4 ]

(i)

State the name of the growth response shown by the plant shoot in Fig. 3.1.

[ 1 ]

(ii)

Explain how the growth of the plant shoot in Fig. 3.1 is controlled.

[ 3 ]

[Maximum number: 1]

The diagram shows an experiment using wheat shoot tips to investigate plant growth.

Which statement is supported by the evidence provided by this experiment?

Auxin moves through the plant by osmosis.

Auxin is made in the shoot tip.

Auxin is unequally distributed in response to light.

Auxin inhibits cell elongation.

[Maximum number: 1]

The diagram shows a shoot that has been placed on its side. The shoot begins to grow upwards.

What causes the shoot to grow upwards?

increased cell division by meiosis at P

increased cell division by mitosis at P

more cell elongation at P than Q

more cell elongation at Q than P

(a)

(i)

Plants also make hormones.

State the name of one hormone made by plants.

[ 1 ]

(ii)

Some plant hormones are manufactured and applied to crops to alter aspects of plant growth.

Describe how the synthetic plant hormone 2,4-D is used in agriculture.

[ 2 ]

[Maximum number: 1]

A student used two seedlings X and Y to investigate phototropism.
The diagram shows their investigation.

Which statement explains the difference in results between X and Y ?

The piece of glass destroyed the auxin on the shaded side of the seedling.

The piece of glass destroyed the auxin on the side of the seedling facing the light.

The piece of glass in X stopped the auxin travelling down the shaded side of the seedling.

The piece of glass in X stopped the auxin travelling down the side of the seedling facing the light.

[Maximum number: 1]

A student used two seedlings X and Y to investigate phototropism.
The diagram shows their investigation.

Which statement explains the difference in results between X and Y ?

The piece of glass destroyed the auxin on the shaded side of the seedling.

The piece of glass destroyed the auxin on the side of the seedling facing the light.

The piece of glass in X stopped the auxin travelling down the shaded side of the seedling.

The piece of glass in X stopped the auxin travelling down the side of the seedling facing the light.

[Maximum number: 1]

The diagram shows the shoot and root of a seedling responding to gravity.

Which row shows where the auxin accumulates and the effect of this in the shoot?

accumulates

effect

lower surface

inhibits cell elongation

lower surface

promotes cell elongation

upper surface

inhibits cell division

upper surface

promotes cell division

[Maximum number: 1]

Some roots are known to be gravitropic.
Which pair of diagrams show a controlled experiment to find out if these roots are also phototropic?

1 and 2

1 and 3

2 and 3

2 and 4