Q: How are responses brought about in our body?
A: Responses are brought about by rapid changes in some muscles and such changes are usually related to changing stimuli. Rapidity of response indicates an efficient communication system linking those parts that pick up stimuli to those that elicit a response.
Q: Give an example for the functions of autonomic nervous system in our activities.
A: Example: When we enter a dark room we cannot see anything immediately. Slowly we are able to see the things around us in the room. This is because of increase in diameter of pupil, which allows more light in. When we come out of the dark room into broad day light the diameter of the pupil decreases allowing less light to enter into the eyes. Both these functions occur under the influence of the autonomic nervous system.
IV. Information Skills and Projects
Q: What is Tropism? Explain in a tabular form.
A: Tropism is a biological phenomenon, indicating growth or turning movement a plant makes in response to an environmental stimulus.
Phototropism: Movement of plants toward light to maximize amount of sun
for photosynthesis to make their food.
Gravitropism: Movement of plants in response to gravity. Positive is toward gravity (roots). Negative is away from gravity (shoot: stems and leaves).
Hydrotropism: Movement by plants towards water. Seen in roots 'searching' and growing toward water which is needed for photosynthesis and to support cell structure.
Thigmotropism: Plants moving in response to touch. Seen in vine plants as they wrap around other plants or structures to support leaves as they grow higher and higher to reach the sun to make more food (photosynthesis).
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