NCERT Solutions for Class 8 Science Chapter 10
NCERT Solutions for Class 8 Science Chapter 10 Reaching the age of Adolescence (अध्याय 10: किशोरावस्था की ओर) to Study online or download free in PDF form free for session 2020-21 following new CBSE Syllabus.Offline Apps 2020-2021 and CBSE NCERT Solutions 2020-21 of class 8 all other subjects are also available.
NCERT Solutions for Class 8 Science Chapter 10
|Chapter 10:||Reaching the age of Adolescence|
Class 8 Science Chapter 10 Answers
NCERT Solutions for Class 8 Science Chapter 10 Reaching the age of Adolescence is given below. Video Format solutions of all chapters of class 8 science are also available free to use online or download. Download 8 Science App for offline use in new session 2020-21.
Class 8 Science Chapter 10 Important Questions for Practice
What is menstruation? Explain.
In a female reproductive ovaries, the ova begin to mature with the onset of puberty. One ovum matures and released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilized and begins to develop. If fertilization does not occur, the released egg and the thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in female which is called menstruation. Menstruation occurs once in about 28 to 30 days.
The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age.
What are sex hormones? Why are they named so? State their function.
Hormones which constitute the secondary sexual characters are called sex hormones. In general, hormones work instantly when they released in blood stream. Sex hormones are different because they start to work later on. They gradually prepare in the body for reproduction.
The sex hormones are responsible for the fundamental change in growth & development and stimulate the developments of secondary sexual characters. The testes and the ovaries are the reproductive Organs and both are stimulated by the pituitary hormone during Puberty. That’s the reason these are called sex hormones.
Functions of Sex Hormones:
In male, the testes produces the male sex hormone testosterone. This hormone helps in the development and maintenance of the primary and secondary sexual characters and production of sperms.
In female, the ovaries secrete oestrogen and progesterone responsible for the primary and secondary sexual characters.
What is the term used for secretions of endocrine glands responsible for changes taking place in the body?
Hormones are chemical messengers that transport signal from one cell (or gland) to another cell (or gland).
Class 8 Science Chapter 10 MCQ with Answers
1. The belief that the mother is completely responsible for the sex of the child is wrong because the child
(a) gets sex chromosome only from the mother.
(b) develops in the body of the mother.
(c) gets one sex chromosome from the mother and the other from the father.
(d) gets sex chromosome only from the father.
2. For the metamorphosis of tadpoles which of the following elements must be available in water?
3. Structures present in a cell which is responsible for determination of the sex of a baby is
(b) cell membrane
4. Given below are events that lead to pregnancy and development of embryo.
(i) Fertilization of egg
(ii) Maturation of egg
(iii) Release of egg
(iv) Embedding of embryo in thickened uterine wall.
Which of the following options gives the correct order of sequence in which they occur?
(a) i, ii, iii, iv,
(b) ii, i, iii, iv
(c) i, iv, ii, iii
(d) ii, iii, i, iv.
5. The most conspicuous visible change that occurs in boys during puberty is:
(a) development in voice box.
(b) increase in height.
(c) production of sperms.
(d) increased sweating.
6. Give a suitable word for each of the following statements.
(a) The site which responds to a hormone.
(b) Name of a gland which transports secretions through ducts.
(c) Chemicals which control changes at adolescence stage.
(d) It marks the beginning of reproductive period.
7. Complete the following sentences.
(a) In females, the uterine wall thickens to receive the __________.
(b) Endocrine glands release hormones directly into _________ for transportation to the __________.
(c) The sex hormones,_______________________ and estrogen are responsible for the development of __________ characters.
(d) Release of sex hormones is under the control of a hormone secreted from the __________.
8. Name the hormone that is released by testes at the onset of puberty.
9. Unscramble the underlined words in the following sentences.
(a) Reproductive life of a woman lasts from hacreemn to spauoemen.
(b) The development of a caterpillar to an adult butterfly is termed as poommertaissh.
(c) The overgrowth of sumselc in xalnyr leads to the hoarse voice in adolescent boys.
(d) Dannalier helps the body to adjust and fight the stress.
10 We should avoid taking medicines/drugs unless prescribed by a doctor. Give reasons.
Answers of Important Questions
6 (a) Target site, (b) Sweat glands/salivary glands/oil glands (any one), (c) Hormones, (d) Puberty
7 (a) fertilised egg. (b) blood stream, target site. (c) Testosterone, estrogen, secondary sexual. (d) pituitary gland.
9 (a) menarche, menopause (b) metamorphosis (c) muscles, larynx (d) Adrenalin
10 Several medicines have adverse side effects and have specific dosage levels which if not followed may harm the body. Drugs can be addictive too and can ruin our health and happiness.