We have just studied that in tropism, a plant part either moves towards the stimulus or away from the stimulus. However, in some plants, the movement of the plant part is neither towards the stimulus nor away from the stimulus. That is, the movement of plant part in some plants is not in a particular direction with respect to stimulus.
1. The movement of a plant part in response to an external stimulus in which the direction of response is not determined by the direction of stimulus is called ______ movement.
(i) Nastic
(ii) Tropic
2. State true or false. The main difference between tropic and nastic movements is that tropic movement is a directional movement of a plant part but nastic movement is not a directional movement of the plant part with respect to the stimulus.
(i) TRUE
(ii) FALSE
3. The direction of nastic movement is _______by the direction from which the stimulus is applied.
(i) Determined
(ii) Not determined
4. State true or false. The folding up of the leaves of a sensitive plant on touching is not a growth movement but the opening and closing of petals of flowers by the action of sunlight is a growth movement.
(i) TRUE
(ii) FALSE
5. Most of the movements of plant parts are very _______.
(i) Fast
(ii) Slow
