Important : Control and Coordination
1. What are ‘hormones’? State one function of each of the following hormones:
(i) Thyroxine (ii) Insulin
Ans. Hormones are the chemical substances which coordinate and control the activities of living organisms and also their growth.
(i) Function of Thyroxine:
This hormone regulates the metabolism of carbohydrates and fats.
(ii) Function of insulin:
This hormone helps in regulating sugar level in the blood.
2. Name and explain the function of the hormone secreted by the pituitary gland in humans.
Ans. Hormones secreted by pituitary gland along with their functions are:
1. Growth hormone: It regulates growth and development of bones and muscles.
2. Trophic hormone: It regulates secretion of hormones from other endocrine glands.
3. Prolactin hormone: It regulates the function of mammary glands in females.
4. Vasopressin hormone: It regulates water and electrolyte balance in the body,
5. Oxytocin hormone : It regulates ejection of milk during lactation.
3. Name the plant hormones which help/promote
(i) cell division
(ii) growth of the stem and roots?
Ans. The plant hormones which help or promote:
(i) Cell division — Cytokinin
(ii) Growth of the stem — Gibberellins
4. What is the function of thyroxine hormone in our body ?
Ans. Thyroxine hormone regulates the carbohydrate, protein and fat metabolism in the body so as to provide the best growth balance.
5. Name two tissues that provide control and coordination in multicellular animals.
Ans. The two tissues that provide control and coordination in multicellular animals are nervous and muscular tissues.
6. What are ‘nastic’ and ‘curvature’ movements? Give one example of each.
Ans. Nastic movements: These are non-directional movements which are neither towards nor away from the stimulus.
Example: Dropping of leaves.
Curvature movements: In such movements plant organs move towards or away from the stimulus.
Example: Bending of shoot towards a source of light.
7.Write the name and functions of any two parts of the human hind-brain.
Ans. Any two parts of human hind-brain with their functions are as follows:
(i) Cerebellum, which controls the coordination of body movement and posture.
(ii) Medulla oblongata, which regulates the centre of swallowing, coughing, sneezing and vomiting.
8. What are plant hormones? Write two important functions of auxin.
Ans. Plant hormones can be defined as a chemical substance which is produced naturally in plants and are capable of translocation and regulating one or more physiological processes when present in low concentration. .
Two important functions of auxin are that it promotes cell elongation, root formation, cell division, etc.
9. Which mechanism control timing and amount of hormone released?
Ans: Feedback mechanism
10. How is spinal cord protected ?
Ans: Vertebral column made by vertebrae protects the spinal cord.
Ashwani Kumar
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