EduNinja• Investigate and describe gravitropism and phototropism in shoots and roots
The nervous system coordinates the responses of animals to changes in their environment.
Fig. 2.3 shows three pots of seedlings that have been kept in different conditions.
Fig. 2.3
State the conditions in which pots P and Q were kept.
P
Q
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
The diagram shows seedlings in two experiments on the tropic response of seedlings to gravity and light.
How have the seedlings responded?
to gravity
to light
key
✓
✓
✓
✓ = tropic response shown
✓
no tropic response shown
The diagram shows an experiment to investigate the response of a plant stem to gravity.
in dark
What is a suitable control for this experiment?
in dark
A seed is placed and grown on a rotating disc, as shown.
Which diagram shows the appearance of the seedling shoot after seven days?
A seed is placed and grown on a rotating disc, as shown.
Which diagram shows the appearance of the seedling shoot after seven days?
Two identical potted plants were used to investigate plant responses.
Plant A was placed on a clinostat that continually rotated. Plant B was not rotated.
Both plants were then placed on their sides and kept in the dark.
Fig. 4.1 shows the two plants at the start of the experiment and after seven days.
Fig. 4.1
Explain the reason for constantly rotating plant A.
A student investigated plant growth responses in roots and shoots. They used this method:
- Damp cotton wool was placed in two Petri dishes.
- Three bean seedlings were attached to the cotton wool in each Petri dish.
- Each seedling was orientated so that the roots pointed in a different direction in each Petri dish.
- Petri dish 1 was kept on its side in a fixed position.
- Petri dish 2 was kept on its side and rotated constantly.
- Both Petri dishes were kept in the dark.
- Both Petri dishes were kept in these conditions for two days.
- After two days the seedlings were observed.
Fig. 6.1 is a diagram of the apparatus.
Petri dish 1
Petri dish 2
Fig. 6.2 shows the seedlings after two days.
Fig. 6.2
Describe the pattern of growth of the bean roots and shoots in Petri dish 1 shown in Fig. 6.2.