8th science: Ch:Reaching the age of adolescence solution of question

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

Ans.

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      Testes matures

releases eggs.               and produces sperms

Q4.  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.

Q5. What are secondary sexual characters?

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

Q6. Define the following terms.

Ans. 1. Hormone- they are chemical messengers for various processes and activities in the body

2. Endocrine glands- the ductless glands which secrete hormones directly into blood.

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

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

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 1become 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.

CBSE Class 8th Science Assignments

CLASS VIII LESSON-11(HUMAN EYE)

Q.1. Explain the structure of eye.
Q.2.How are we able to see in dim and bright light?
Q.3.What is the function of the ciliary muscles?
Q.4.What kind of image is formed by eye-lens?
Q.5.What are photo receptors?
Q.6.How we can see colours?

Q.7.What is persistence of vision?

Q.8.How does persistence of vision help to see the object as moving?

Q.9.How are we able to see a moving picture?
Q.10.Which principle is used in cinematography?
Q.11.What happens when an object is brought closer to the eye and why?
Q.12.What is the near point of the eye?
Q.13.What are the two defects of the eye?
Q.14.What are the different reasons for vision problems?

Q.15.Who developed Braille system?

LESSON ---- 15 ( REACHING THE AGE OF ADOLESCENCE )

Q.1.What initiates changes at puberty?
Q.2. Is there any role of hormones in completing life history of insects and frogs?
Q.3.What is the function of endocrine system?
Q.4.Name the major glands that make up the endocrine system.
Q.5. Write a short note on Adam’s apple.
Q.6. Name some vitamins and minerals needed by adolescents to build strong and healthy bones.
Q.7.Name the hormones released by the various glands in our body. Mention the function of each hormone.
Q.8.Write some habits that adolescents need to adopt to maintain personal hygiene.
Q.9.Discuss the consequences of taking drugs by the adolescents.
Q.10. Is mother responsible for determining the sex of a child? Give reasons for your answer.

Lesson 13 ( Synthetic Fibres and Plastics) 

Q1. Give some examples of Natural and Synthetic fibres.
Q2. What are monomers and polymers ?
Q3. What is polymerisation ?
Q4. What is Rayon ? Why is it not truly an artificial fibre ?
Q5.Give some features and uses of Terylene and acrylic fibres.
Q6. What are the advantages of synthetic fibres ?
Q7. Write some disadvantages of synthetic fibres.
Q8. What are plastics ? What are its different types ?
Q9. Differentiate between Thermoplastics and Thermosetting plastics.
Q10. What are the characteristics of synthetic plastics ?
Q11. Differentiate between biodegradable and non-biodegradable.
Q12. Give some measures to control the damage caused by plastic waste.
Q13. Name the first fully synthetic fibre. What are its different uses ?
Q14. Should the handle and bristles of a tooth brush be made of the same material ? Explain your answer.
Q15. Explain why the following materials are made of thermosetting plastics –
(i) Saucepan handles      (ii) Kitchenware

LESSON- 14 (REPRODUCTION IN ANIMALS )

Q.1. Define the following terms -- reproduction , hatching.
Q.2.Explain the process of budding in hydra and yeast.
Q.3. How does external fertilization take place in frogs?
Q.4. Explain the male reproductive system in humans.
Q.5.Draw the diagram of human sperm and explain its structure.
Q.6. Differentiate between asexual and sexual reproduction.
Q.7. Why does a child show some characteristics of the father and some of the mother?
Q.8. Explain the importance of reproduction in organisms.
Q.9. Differentiate between oviparous and viviparous animals.
Q.10.Why do fish and frogs lay eggs in hundreds whereas a hen lays only one egg at a time?

CHAPTER – 9(CROP PRODUCTION AND ITS MANAGEMENT) 

Q1 What is crop production?
Q2 Define agriculture and agricultural practices.
Q3 What are rabi crops?
Q4 Write agricultural practices required for growing crops.
Q5 What is soil made up of ?
Q6 Write short note on ”SOWING”and “SEED DRILL”.
Q7 What is manuring? Why is it important?
Q8 How do farmers prepare manure?
Q9 What are the advantages of manure?
Q10 Why is overuse of fertilizer harmful?
Q11 How do leguminous plants help in increasing the nitrogen content of the soil?
Q12 Define irrigation. How is it done ?
Q13 Why is the minimum use of pesticides advised?
Q14 What is harvesting? What are its different methods?
Q15 What is winnowing? How is it done?
Q16 Why do we sundried the grains before storing?
Q17 What is green revolution?
Q18 Why were Mexican wheat introduced in India?
Q19 Define – Hybridization , Emasculation .
Q20 Why is cross breeding done?
Q21 Where is hybridization done?
Q22 How can we provide food to a large number of people in our country?
Q23 Why can paddy not be grown in the winter season?
Q24 Why do some plants grow better than others?
Q25 Explain how fertilizers and manures are different from each other.

Source :www.davblb.ac.in

Reaching the age of adolescence for class 8 Assigments

SET-I
Reaching the Age of Adolescence
1. Define puberty, Adolescence, Menstruation, Ovulation, Menopause
2. What is the function of endocrine glands?
3. Give the function of followings a, Adrenal glands b. Pancreas c. Thyroid glands d. Pituitary glands
4. What changes occur in puberty?
5. Why is pituitary glands called “master glands”?
6. What is menstrual cycle?
7. Explain what determine the sex of baby?
8. What causes pimple ton appear in the adolescence?
9. What are the things needed for the adolescents to maintain proper health?
10. What is menarche?
SET-II
Section-A

1. Define the following terms:-
    (a)Infancy (b)Childhood (c)Adolescence (d)Adulthood (e)Puberty

2. Give the suitable term for the follwing:-
     (a) Protruding voice box in human males
     (b) Glands without ducts
     (c) Endocrine gland attached to brain
     (d) Secretion of endocrine glands
     (e) Pancreatic hormone
     (f) Male hormone
    (g) Female hormone
    (h) Secretes Thyroxine
    (i) Another term for Teenage
    (j) Term for changes at Adolescence
   (k) Voice box
3. What are Secondary sexual characters?
4. What are hormones?
5. Define Metamorphosis.
Section-B
1. List the various changes that take place in the body at Puberty.
2. Explain how the following conditions occur & which gland is responsible for them:-
(a)Dwarfism (b)Gigantism (c)Diabetes (d)Goitre
3. Give reasons for the following:-
(a)Pituitary is called the master endocrine gland
(b)We must consume iodised salt
(c)Diabetics are given insulin injections
(d)Adrenalin is also called the “stress hormone”
(e)Personal hygiene & regular physical exercise are essential for our well being
4. What are sex hormones? Why are they named so? State their functions.
5. What is Metamorphosis & how is it controlled?
6. What are the major events that occur during Menstruation?
7. Chips & tinned/packed snacks, though tasty should never replace regular meals. Why?
8. Justify the statement-“Say NO to drugs, tobacco & alcohol”.
9. What are some ways in which HIV is transmitted from an infected person to a normal one?
10. How is menarche different from menopause?
LONG ANSWER TYPE QUESTIONS:-
1. What are Chromosomes? What is their significance in our body?
2. How is the gender/sex of a baby determined in humans?
3. List down the major pubertal changes in human males (any 5).
4. List down the major pubertal changes in human females (any 5).
5. Tabulate the various Endocrine glands, their hormones & their functions

Reaching the age of adolescence CBSE VIII-BIOLOGY

8ts Reaching the age of adolescence
Growth begins from the day one is born. But upon crossing the age of 10 or 11, there is a sudden spurt in growth which becomes noticeable. The changes taking place in the body are part of
growing up. They indicate that you are no longer a child but are on the way to becoming an adult.

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.

Questions:1. What is adolescence?

Ans: It is the period of life when the body undergoes changes, leading to reproductive maturity.
Questions:2. Define puberty.
Ans: The stage when human body becomes sexually mature.
Questions:3. Enlist the changes occurring in males and females during puberty.
Ans: Type of change               In girls                  In boys
Increase in height         Sudden in crease        Sudden in crease
Body shape                  Waist widens             Shoulders broadens
Voice change               High pitched             Voice becomes deeper
Development               Ovaries mature           Testes matures and
of sex organs               and releases eggs.       produces sperms
Questions:4. 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.
Questions:5. What are secondary sexual characters?
Ans: These are the features that help to distinguish males from females.
Questions:6. Define the following terms.
Ans:  1. Hormone- they are chemical messengers for various processes and activities in the body
          2. Endocrine glands- the ductless glands which secrete hormones directly into blood.
Questions:7. 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.
        2. These sex hormones reach to target sites via blood.
        3. Then stimulate changes in the body at the onset of puberty.
Questions:8. 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.
Questions: 9. Give reasons for the following :
1. 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.
2. Voice becomes hoarse in adolescent boys.
Ans: Sometimes the muscles of the growing voice box go out of control and the voice becomes
hoarse.
3. Adolescents experience acne and pimples.

Ans: This is dues to increased activity of sebaceous (oil) glands in the skin.
4. 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 the
sperms are of two types, having either X or Y chromosome.
Questions: 10. Name the hormone secreted by the following glands, write their functions as well.
Ans: Gland            Hormone             Function
Pituitary          Growth hormone        Controls the activities of other
                                                           glands and helps in growth
Thyroid              Thyroxine               Metabolism of carbohydrates,fats
Pancreas               Insulin                  Regulates sugar metabolism of
                                                          sugar, deficiency causes diabetes.
Adrenal              Adrenaline              Helps body to fight stress
Questions: 11. Write short note on reproductive health of adolescents.
Ans:1. Nutritional needs of adolescents 

2. personal hygiene
3. physical exercise
Questions:12. What are the causes of AIDS?
Ans: 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.