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प्रश्न
What is meant by positive phototropism and negative phototropism? Give one example of each type.
उत्तर
The movement of plant parts towards the light source is known as positive phototropism, whereas the movement of plant parts away from light is known as negative phototropism. The stems of plants show positive phototropism as they grow upwards. The roots of plants show negative phototropism as they grow downwards into the soil.
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संबंधित प्रश्न
Give the scientific terms used to represent the Bending of roots towards water.
What does a root do in response to gravity? What is this phenomenon known as?
Give one example of the movement of a plant part which is caused by the loss of water (or migration of water).
The root of a plant is :
(i) positively phototropic but negatively geotropic
(ii) positively geotropic but negatively phototropic
(iii) negatively phototropic but positively hydrotropic
(iv) negatively hydrotropic but positively phototropic
(a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (d) (i) and (
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.
Answer the following question.
What is tropism?
Roots of plants are:
The plant part which exhibits negative geotropism is ______.
What is the other name for thigmonasty?
Give one example of geotropism.
