Question

State one similarity and one different between the responses of tropism and nastic movement

Answer 1

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Nastic movements- are non-directional responses of plants to a stimuli such as temperature,light,change in turgor pressure or change in ion concentration.

Eg- dropping of the Mimosa leaf on being pricked. Tropisms- are directional responses to a directional stimulus.

Answer 2

Similarity between tropic and nastic movement is - both are the result of external stimulus and the difference between tropic and nastic movement is the direction of the response is not dependent on the direction of the stimulus in case of nastic movement but in case of tropic movement the response is dependent on the direction of stimulus.

• Definition: The movement of plant part in a particular direction in relation to the stimulus is called tropic movement.
• Tropic movements can be either towards the stimulus, or away from the stimulus.
• For example: the movement of a plant shoot towards the light and plant root away from light.
• Definition: Nastic movements in plants are reversible and repeatable movements in response to a stimulus whose direction is determined by the anatomy of the plant.
• Nastic movements occur in response to environmental stimuli.

• Example:diurnal movement of leaves and the response of insectivorous plants,  opening or closing of flower.