Question 36:
(a) How does control and coordination take place in plants ? How does it differ from that in animals ?
(b) Name five stimuli which act on plants. Name the type of tropism produced by each one of these stimuli.
(c) Define hydrotropism. Give one example of hydrotropism. State whether this example is of positive hydrotropism or negative hydrotropism. Illustrate your answer with the help of labelled diagram.
Lakhmir Singh Biology Class 10
Answers
Answer:
here is the answer
Explanation:
a.) Chemical coordination in plants are occurred in plants with the help of fluids secreted in plants known as phytohormones or plant hormones. These hormones regulate the growth of the plants. For example auxin responsible for the growth of the plants and the Cytokinin helps in cell division in the fast growing part of the plant such as plant hormones.
b.)There are five stimuli in the environment. They are light, gravity, chemical, water and touch. These stimuli give five types of tropism. They are phototropism, geotropism, chemotropism, hydrotropism and thigmotropism.
c.)When a plant part moves in response to water, it is called hydrotropism. Here the stimulus is water. Roots of a plant moves towards water, so they show positive hydrotropism
a) The plants do not have a nervous system but they can sense things in the presence of stimuli such as light, touch, water etc. and respond to them by the action of hormones. Thus, the plants coordinate their behavior against environmental behavior by using organic chemicals called hormones. This is called chemical coordination. The hormones in plants coordinate their behavior by affecting the growth of a part of the plant resulting in the movement of that plant part in response to a stimulus. The control and coordination in animals takes place by both nervous system and hormones.
(b) (i) Light – Phototropism.
(ii) Gravity – Geotropism.
(iii) Chemical – Chemotropism.
(iv) Water – Hydrotropism.
(v) Touch – Thigmotropism.
(c) The movement of a plant part in response to water is called hydrotropism. Example: The roots of a plant always go towards water, this is positive hydrotropism
