NCERT solution for class 8 //Science// Chapter 10 Reaching the age of adolescence

 NCERT solution > class 8> Science 

Chapter 10 - Reaching the age of adolescence 

Exercise 

Q1. What is the term used for chemical secretion of endocrine glands responsible for changes taking place in the body? 

Answer- Hormone term is used for the chemical secretion of endocrine glands responsible for changes taking place in the body

Q2. Define adolescence? 

Answer- The period of life when the body undergo number of changes leading to reproductive maturity is called adolescence 

Q3. What is menstruation explain? 

Answer- In females after the age of 13 ovary become mature and released by one ovary once in about 28 to 30 days during this period uterus undergo number of changes in become thick and fleshy to receive the egg .in case it is fertilized and the situation in females is known as pregnancy.

But if the egg is not fertilized then the lining of the uterus along with the blood vessels becomes breast and shade of through the vagina that is the female reproductive organ and this causes bleeding in women it is called menstruation

Q4. List changes in the body that takes place at puberty? 

Answer- There are number of changes takes place in both boys and girls body after puberty 

  • Boys and girls both become capable of reproduction 
  • Suddenly their height increases .
  • The voice of the boys become hoares due to development of Adam's Apple 
  • Hair start growing on different body parts 
  • In girls development of breast 

Q5. Prepare the table having two columns depicting names of endocrine glands and hormones secreted by them?

Answer- 


Q6. What are sex hormones why are they named so state their functions? 

Answer- Sex hormone are the chemical substance produced by sex organ 

Example - In male testes produced testis is a male sex hormone and in female horoscope reduce oestrogen is a female sex hormone.

Functions of sex hormone 

Testis tirone stimulate the secondary sexual characters in boys like growth of beard and moustache voice becoming hoarse development of reproductive organs etc.

Oestrogen is responsible to to stimulate the development of female reproductive organ and  enlargement of breast 

Q7. Choose the correct options? 

a) Adolescents should be careful about what they eat because 

i) Proper diet develop 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 birds are well developed in teenagers .

Answer-ii) 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) Breast start developing 

iii) Body weight increases 

iv) Height increases 

Answer- i) Menstruation starts

c) The right meal for adolescents consists of

i) Chips ,noodles,coke 

ii) Chapati ,dal ,vegetables 

iii) Rice ,noodles and burger 

iv) Vegetable, cutlets, chips and lemon drink  

Answer - Chapati ,dal ,vegetables

Q8. Write notes on- 

a) Adam's Apple 

b) secondary sexual characters 

c) determination in the unborn body 

Answer-  

a) Adam's Apple 

In human larynx grow larger during puberty and can be seen as a protruding part of the throat. This is known as Adam's Apple due to increasing size of the vocal cord the voice become hoarse .

b)Secondary sexual characters 

The sexual characters which show in girls and boys after puberty are known as secondary sexual characters 

Secondary sexual characters in boys 

  • Appearance of moustache and beard 
  • Growth of hairs in genital area and chest part and other part of skin 
  • Increasing the size of vocal cord 

Secondary sexual characters in girls 

  • Increasing the size of breast 
  • Growth of hair on genital area and other body parts 
  • Start of menstrual cycle 

 c) Sex determination in an unborn baby. 

The sex type of the unborn baby is determined by the type of male gamete that fuses with female gamete . All humans when have 23 pair of chromosome out of the 23 pair of chromosome one is the sex chromosome in male xy type of sex chromosome is found while in female XX type of sex chromosome in found when x sperm in male combined with X ovum in female then the sex of baby is daughter but when the Y sperm is fuses with X ovum in female then the baby is formed as a  son.


Q9. Word game use the clues to work out the words. 

Across 

3. Protruding voice box in boys 

4. Glands without ducts 

7. Endocrine gland attached to brain 

8. Secretion of endocrine glands 

9. Pancreatic hormones 

10. Female hormone 

Down 

1. Male hormone 

2. Secrets thyroxine 

3. Another term for Teenage 

5. Hormone reaches here through bloodstream 

6. Voice box 

7. Term for changes at adolescence .  




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