Wednesday, September 26, 2012

8th science: Ch:Reaching the age of adolescence solved questions

CBSE Science  Chapter : Reaching the age of adolescence
Q1. What is adolescence?

Ans. It is the period of life when the body undergoes changes, leading to reproductive maturity.

Q2. Define puberty.

Ans. The stage when human body becomes sexually mature.

Q3.  What is adam’s apple?

Ans. The growing voice box in boys can be seen as a protruding part of the throat called adam’s apple.

Q4. What are secondary sexual characters?

Ans.These are the features that help to distinguish males from females.

Q5. Define the following terms. (a) Hormone (b) Endocrine glands

Ans. (a) Hormone- they are chemical messengers for various processes and activities in the body
        (b) Endocrine glands- the ductless glands which secrete hormones directly into blood.

Q6. Enlist the changes occurring in males and females during puberty.

Type of change
In girls
In boys
Increase in height
Sudden increase
Sudden in crease
Body shape
Waist widens
Shoulders broadens
Voice change
High pitched
Voice becomes deeper
Development of sex organs
Ovaries mature and releases eggs.
Testes matures and produces sperms

Q7. What is the role of hormones in initiating reproductive function?

Ans.1. Hormones from pituitary stimulate testes and ovaries to release testosterone and  estrogen  respectively.

3. These sex hormones reach to target sites via blood.

4. Then stimulate changes in the body at the onset of puberty.

Q8.  Discuss reproductive phase of life in women.

Ans. In females the reproductive phase of life begins at puberty and continues till they reach the age of 45-50 years. The egg begins to mature with the onset of puberty. One mature ovum is released by one of the  ovaries every month. The process is called ovulation. During this period, the walls of the uterus become thick  so as to receive fertilized egg.  Then this egg gets implanted in the uterus resulting in pregnancy.

Q9 Give reasons for the following :

a. Tadpoles growing in iodine deficient water have retarded growth.

Ans. The process of growth and development is regulated by thyroxine hormone which is produced by thyroid gland. Iodine is required for thyroxine production. That is why retarded growth is seen in tadpoles living in iodine deficient water.

b. Voice becomes hoarse in adolescent boys.

Ans. Sometimes the muscles of the growing voice box go out of control and the voice becomes hoarse.

c. Adolescents experience acne and pimples.

Ans. This is dues to increased activity of sebaceous (oil) glands in the skin.

d. Females have no role in determining gender of a child.

Ans. Y- chromosomes that leads to a boy offspring is contributed by male parent. That is thesperms are of two types, having either X or Y chromosome.

10. What are the causes of AIDS?

Ans. The causes of AIDS are:
1. Sharing needle of the syringe            
2. unprotected sex with infected person.        
3. blood transfusion from infected person to healthy one.
4. infected mother can pass HIV through milk to an infant.
8th Chapter: Reaching the Age of Adolescence
[Study Notes] by Educational service
CBSE Solved Questions Paper-1
CBSE Solved Questions Paper-2
CBSE Solved Questions Paper- 3
CBSE Solved Questions Paper- 4
VIII  Reproduction in Animals    
Reproduction in Animals  [E-NOTES]
CBSE Test Paper  [solved question]
CBSE Worksheet for practice
Reproduction & Endocrine [solved]

1 comment:

J Sunil said...

Chapter 10- Reaching the age of Adolescence
Answer the following questions
1. Name the hormone produced when one is very angry or worried.
2. The chemicals secreted by endocrine gland are called _________.
3. How many pairs of chromosomes are found in the nuclei of their cell?
4. Why endocrine glands are termed ductless glands?
5. Name the disease caused due to lack of insulin producation.
6. Name the hormone that controls metamorphosis in a frog. Name the mineral required by this hormone.
7. Name the gland which controls the activity of other endocrine glands.
8. Name the hormone which maintains the correct salt balance in the blood.
9. Name three glands which release their secretions through ducks.
10. Name the hormone produced by thyroid gland and the disease caused due to lack of its producation.
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