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Coordination in plants

Porous container

Root grows Water
toward water

FOR ONLINE READING ONLY
Root grows
straight
Moist soil

Dry soil Moist soil

Figure 1.8: Hydrotropism

Importance of hydrotropism
Activity 1.1:
It enables the plants locate and absorb
Determining the effect of water on root dissolved minerals and water. Water is
growth necessary for various functions including
Materials photosynthesis and numerous physiological

Wire gauze, bean seedling, cotton wool reactions that take place within plant cells.
and two retort stands Another function of water is to maintain
Procedure turgor pressure which aids in plant support.
1. Secure a wire gauze horizontally Water also helps in dissolving mineral
using two retort stands. salts and their transportation throughout
the plant.
2. Place the bean seedling on the wire
gauze in such a way that the radicles Thigmotropism or thigmotropic
pass through the pores of the wire movement
gauze.
This is the growth movement of a part of
3. Put wet cotton wool above the gauze. plant in response to touch or mechanical

4. Leave the set for four days. Make contact. This movement is found in
sure that the cotton wool is kept wet. climbing and twining plants. Tendrils of
climbing plants bend around objects such as
5. After four days observe what happens fences, buildings and trees that they come in
to the roots. contact with as seen in Figure 1.9. This is a
Question typical example of positive thigmotropism.

Explain the changes that occur after four Upon contact, auxin redistribution causes
days. faster growth on the opposite side, enabling
curling. This adaptation helps plants secure
sunlight and structural support.

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