Coordination and Response in Plants
12 questions· page 1 of 2
Why do plant shoots grow towards light?
Options
A Auxin inhibits cell elongation on one side.
B They grow more rapidly on the lighter side.
C More auxin accumulates on the darker side.
D Auxin stimulates cell division.
The diagram shows a plant grown on its side without light.
Which row explains the responses shown by the roots and the shoot?
Options
| roots | shoot | |
|---|---|---|
| A | positive gravitropism | positive phototropism |
| B | negative phototropism | positive phototropism |
| C | positive gravitropism | negative gravitropism |
| D | negative gravitropism | positive gravitropism |
The tips of growing shoots of a plant are cut off and placed on small blocks of jelly which contain no auxin.
Small pieces of impermeable clear glass are placed in some of the jelly blocks, as shown in diagram X. Some of the shoot tips are divided by impermeable clear glass pieces, as shown in diagram Y.
The tips are left on the small blocks of jelly with light coming from one side only.
After 12 hours, the number of arbitrary units of auxin is measured in each of the jelly blocks and the means, shown in the diagrams, are calculated.
A student wrote down some conclusions from the results.
- Auxin moves downwards out of the shoot tip.
- The distribution of auxin in a shoot tip is affected by light intensity.
- Some auxin is destroyed by light.
- Auxin moves from areas of more light to areas of less light.
Which of the student's conclusions are correct?
Options
A 1, 2, 3 and 4
B 1, 2 and 4 only
C 1 and 3 only
D 2, 3 and 4 only
What is a correct example of phototropism?
Options
A A stem grows away from gravity.
B A root grows towards light.
C A root grows towards gravity.
D A stem grows towards light.
The diagrams show experiments to investigate the response of plant shoots to light.
Which shoot will not grow towards the light?
Options
Five experiments were carried out to investigate the phototropic response of shoots. The diagrams show how the growing shoots of the plants were treated.
Which shoot tips showed a positive phototropic response when light was shone on them from one side?
Options
A 1 and 2
B 2, 3 and 4
C 2, 4 and 5
D 2 and 4 only
Which flow diagram describes how auxin affects growth in negative gravitropism?
Options
Some seedlings were grown in a dark, warm and humid environment. The tips of the growing shoots were cut off and then replaced on one side of the shoot as shown. The shoots were then left to grow.
Which pattern of growth was then seen in the shoots?
Options
A The shoots stopped growing.
B The shoots grew straight up.
C The shoots grew with a curve to the left.
D The shoots grew with a curve to the right.
Auxin is a chemical produced by plants.
What is the role of auxin?
Options
A It stimulates cells in the plant shoot to elongate.
B It stimulates meiotic cell division.
C It stimulates the development of a branching root system.
D It stimulates the process of seed germination.
Which statement about auxin is correct?
Options
A Auxin is equally distributed in the plant in response to gravity and light.
B Auxin inhibits cell elongation.
C Auxin is made in the plant stem.
D Auxin spreads through the plant from the shoot tip.