หน้า ??
there are two types of responses, namely tropism and nastic movements.
tropisms
tropisms are growth responses of plants to external stimuli, tropisms occur slowly. most often they are now noticeable.
in a tropism, a part of the plant grows in a certain direction as a response to a specific stimulus. when the part of the plant grows towards the stimulus, the response is known as positive tropism. when the part of the plant grows away from the stimulus, the response is known as negative tropism.
four common tropisms in plants are as follow.
(a) phototropism
(b) geotropism
(c) hydrotropism
(d) thegmotropism
phototropism is the growth movement shown by plants in response to light. shoots grow towards light. theey are said to show positive phototropism. roots grow away from light. they show negative phototropism. positive phototropism of the shoots ensures that the leaves receive enough sunlight for photosynthesis. this is important for the survival of plants.
geotropism is the growth movement shown by plants in response to gravity. no matter how a seed is planted in the soil, it can detect the gravity and grow in the correct direction.