NCERT Solutions of Chapter: Reaching the Age of Adolescence. NCERT Solutions along with worksheets and notes for Class 8.
(1) What is the term used for secretions of endocrine glands responsible for changes taking place in the body?
Ans– Hormone is used for secretions of endocrine glands responsible for changes taking place in the body.
(2) Define adolescence.
Ans- Adolescence is the age of human when body undergoes many changes like height, voice modulation, facial hair growth etc. and body leads to reproductive maturity. The age of adolescence begins from 11 and lasts up to 18 years. Adolescents are also called”teenagers” because age of adolescence covers age of teens, ie, from thirteen to eighteen.
(3) What is menstruation? Explain
Ans- Mensuration is a process of bleeding which occur in females after every 28 – 30 days when a matured ovum is released by one of the ovaries and received by the uterus whose wall become thick to receive egg. If this egg does not fertilised, the released egg and thickened lining of the uterus with its blood vessels shed off and caused bleeding in women.
(4) List changes in the body that take place at puberty.
(i) Increase in height begins in adolescence at puberty.
(ii) Change in body shape begins at the age of adolescence. Boys shoulder and chest broaden and lower portion of girl’s waist becomes wider
(iii) Voice of teenagers changes at puberty.
(iv) Activities of sweat and sebaceous glands increased.
(v) The sex organs develops at puberty.
(vi) Teenagers reached at mental, instinctual and emotional maturity.
(5) Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.
Ans- Endocrine glands and hormones secreted by them are tabulated below:-
|Endocrine Glands||Hormones secret ad by endocrine glands|
(6) What are sex hormones? Why are they named so? State their function.
Ans- The hormones which control changes in the adolescence are called sex hormones. These are testosterone and estrogen.
The hormone which is released by the testes and caused changes in the male like growth of facial hair is called male hormone or testosterone.
The hormone which is released by the ovaries and caused breast development in the female is called female hormone or estrogen.
(7) Choose the correct option.
(a) Adolescents should be careful about what they eat, because
(i) proper diet develops their brains.
(ii) proper diet is needed for the rapid growth taking place in their body.
(iii) adolescents feel hungry all the time.
(iv) taste buds are well developed in teenagers.
Ans- Adolescents should be careful about what they eat, because proper diet is needed for the rapid growth taking place in their body.
(b) Reproductive age in women starts when their
(i) menstruation starts.
(ii) breasts start developing.
(iii) body weight increases.
(iv) height increases.
Ans– Reproductive age in women starts when their menstruation starts.
(c) The right meal for adolescents consists of
(i) chips, noodles, coke.
(ii) chapatti, dal, vegetables.
(iii) rice, noodles and burger.
(iv) vegetable cutlets, chips and lemon drink.
Ans- The right meal for adolescents consists of chapatti, dal, vegetables.
(8) Write notes on –
(a) Adam’s apple.
(b) Secondary sexual characters.
(c) Sex determination in the unborn baby.
(a) The growing voice box which can be seen as a protruding part of the throat is called Adam’s apple. Girls have small Adam’s apple which can not be visible from outside.
(b) The characters which can distinguish between male and female are called secondary sexual characters.
Eg:- Hair begin to grow on chest, face in boys.
The breast develops in the girls.
Hair grows in arms pit and in the pubic region in boys and girls.
(c) All human beings have 23 pairs of chromosomes in the nuclei of their cell. 2 chromosomes out of 23 chromosomes are the sex chromosomes. These are X and Y chromosomes. A female has two X chromosomes. A male has a set of X and Y chromosomes. The gametes (egg and sperm) have only one set of chromosomes. It means the unfertilized egg has only X chromosomes but the sperm can have either X chromosomes or Y chromosomes.
If sperm containing X chromosomes fertilised egg then, a zygote will have two X Chromosomes. It will result in the development of female child .if sperm containing Y chromosomes fertilised egg then, a zygote will have one X Chromosomes and one Y chromosomes. It will result in the development of male child.
(9)Word game: Use the clues to work out the words.
- Protruding voice box in boys.
- Glands without ducts.
- Endocrine gland attached to brain.
- Secretion of endocrine glands.
- Pancreatic hormone
- Male hormone
- Secretes thyroxine
- Another term for teenage
- Hormone reaches here through blood stream
- voice box
- term for changes at adolescence