Q. 94.9( 10 Votes )


Answer :

i. The swollen neck in people living in the hills is due to the under secretion of thyroxine or improper functioning of thyroid gland.


1. Near the neck region, there exists very important endocrine gland which is called as the thyroid gland.

2. Endocrine glands are the special types of glands in the human body which secretes their secretion called as hormones directly into the bloodstream.

3. The thyroid gland is responsible for the secretion of thyroxine hormone. Thyroxine is responsible for controlling the metabolic rate and growth of the body.

4. Thyroid glands require iodine for their proper functioning. In the hilly regions, the water usually does not contain iodine and hence the normal functioning of the thyroid gland is disrupted which causes the thyroid gland to swell and hence the neck appears to be swollen for the people living in hilly regions.

ii. Over secretion of Growth Hormone during childhood may lead to gigantism a medical condition in which humans acquire very great height above 1.9 m.


1. Growth hormone is released by the pituitary gland which is also called as the master endocrine gland as it controls the functioning of other glands.

2. Growth hormone is responsible for the overall growth of the body for childhood till adult phase as it regulates the growth and elongation of bones and muscles of the body.

3. Usually, the growth hormone is secreted in large quantities during the puberty phase. Oversecretion of growth hormone results in extra elongation of bones and hence the person attains greater height as compared to the normal person. This condition is called gigantism. Under secretion of growth hormone causes dwarfism.

iii. Appearance of secondary sexual characteristics in boys at the age of 13 is due to the secretion of testosterone.


1. Facial hairs, deep voice etc. are the features pertaining to the male human beings.

2. The age of 11 to 13 forms the puberty phase for the male humans, and hence it is during this phase that boys develop their secondary sexual characteristics.

3. Also, during the puberty phase, only the growth of the boys is enhanced due to large secretion of growth hormones.

4. The development of the male features is mainly due to the secretion of male sex hormones called testosterone which regulates the functioning of male reproductive systems and the development of the male secondary sexual characteristics.

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