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Question
Plant parts show two types of movements, one dependent on growth and other independent of growth. Give one example which does not depend on growth
Solution
Thigmonasty does not depend on growth. It is a non directional movement of plant part, such as leaves, in response to touch.
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RELATED QUESTIONS
What is a plant hormone? Name four plant hormones. State one function of each.
P and Q are two types of plants having weak stems which cannot stand upright on their own. The plants P and Q have organs R and S respectively which can grow towards any support which they happen to touch and wind around that support. It is observed that organ R originates from the leaves of the plant whereas organ S originates directly from the stem of the plant.
(a) What is (i) R, and (ii) S?
(b) What is the name of growth movement exhibited by the organs R and S?
(c) Name the stimulus involved in this case.
(d) State whether the behaviour of organs R and S is a tropic movement or a nastic movement.
(e) Name one plant like P and another plant like Q.
Differentiate phototropism from photonasty.
The movement of shoot towards light is
Analogy:
Towards a stimulus: ______:: Away from the stimulus: Negative tropism.
Assertion (A): If the plant part moves in the direction of gravity, it is called positive geotropism.
Reason (R): Stem shows positive geotropism.
While conducting experiments to study the effects of various stimuli on the plants, it was observed that the roots of plant X grow and bend towards two stimuli A and B but bend away from a third stimulus C. The stem of the plant X however bends ” away from stimulus A and B but bends towards the stimulus C. The stimulus B is known to act on the roots due to factors related to Earth. Keeping these points in mind, answer the following questions:
- What could be stimulus A?
- Name the stimulus seen in B.
- What could be stimulus-C?
Give one example of geotropism.
Name the stimulus which causes the following movement in plant:
Thigmotropism
Define the following term:
Heliotropism
