RBSE Class 8 Science Important Questions Chapter 10 Reaching the Age of Adolescence

Rajasthan Board RBSE Class 8 Science Important Questions Chapter 10 Reaching the Age of Adolescence Questions and Answers.

RBSE Class 8 Science Chapter 10 Important Questions Reaching the Age of Adolescence

Objective Questions

Question 1.    
The male hormone is
(a) Estrogen    
(b) Progerostron
(c) Testosterone    
(d) All of the above
Answer:
(c) Testosterone

Question 2.    
The female hormone is
(a) Estrogen    
(b) Testosterone
(c) Thyroxine    
(d) Insulin
Answer:
(a) Estrogen    

Quesstion 3.
Menopause means
(a) Puberty
(b) Deficiency of thyroxine
(c) Increase of thyroxine
(d) Increase of insulin
Answer:
(c) Increase of thyroxine

Question 4.    
If a sperm containing X chromosome fertilises the egg, then the developed child will be
(a) Female    
(b) Male
(c) No male, no female 
(d) Twins
Answer:
(a) Female 

Question 5.
Goitre is caused due to
(a) Deficiency of insulin
(b) Deficiency of thyroxine
(c) Increase in thyroxine level
(d) Increase in insulin level 
Answer:
(b) Deficiency of thyroxine

Fill in the blanks

1. Adolescents are also called ........................
Answer:
teenagers

2. Puberty and maturation of reproductive organs are controlled by ........................ 
Answer:
hormone

3. ........................ is a female hormone.
Answer:
Estrogen

4. Pancreas produce the ........................ hormone.
Answer:
insulin.

True/False

Indicate whether the following statements are true (T) or false (F)

1. Changes during adolescence mark the onset of puberty.
Answer:
True

2. In adolescent boys the voice is high pitched.
Answer:
False

3. Hormones are chemical substances.
Answer:
True

4. Testes secretes the estrogen hormon.
Answer:
False

5. Stop of menstruation is called menarche.
Answer:
False

6. Y containing chromosome sperm fertilized to egg develop into male child.
Answer:
True

Match the words given in 'Column-A' with 'Column-B'

Question 1. 

Column-A	Column-B
(i) Testosterone	(a) Thyroid gland
(ii) Estrogen	(b) Pancreas
(iii) Thyroxine	(c) Testes
(iv) Insulin	(d) Ovaries

Answer:

Column-A	Column-B
(i) Testosterone	(c) Testes
(ii) Estrogen	(d) Ovaries
(iii) Thyroxine	(a) Thyroid gland
(iv) Insulin	(b) Pancreas

Question 2.

Column-A	Column-B
(i) Goitre	(a) Insulin
(ii) Diabetes	(b) Thyroxine
(iii) Metamorphosis	(c) Insect hormone
(iv) Stress	(d) Adrenaline

Answer:

Column-A	Column-B
(i) Goitre	(b) Thyroxine
(ii) Diabetes	(a) Insulin
(iii) Metamorphosis	(c) Insect hormone
(iv) Stress	(d) Adrenaline

 
Question.3

Column-A	Column-B
(i) Secondary sexual characters	(a) Fertility development
(ii) Metamorphosis	(b) Stoppage of menstruation
(iii) Puberty	(c) Growth of facial hairs
(iv) Menopause	(d) Change from larva to adult

Answer:

Column-A	Column-B
(i) Secondary sexual characters	(c) Growth of facial hairs
(ii) Metamorphosis	(d) Change from larva to adult
(iii) Puberty	(a) Fertility development
(iv) Menopause	(b) Stoppage of menstruation

Very Short Answer Type Questions

Question 1. 
Write the formula to calculate the full height in human.
Answer:
Full height = \(\frac{\text { Present height }(\mathrm{cm})}{\% \text { of full height at this stage }}\) x 100

Question 2. 
In which years of age boys - girls attain the maximum height?
Answer:
About 18 years of age.

Question 3. 
What is meant by ductless glands? 
Answer:
Endocrine glands are called ductless glands because their chemicals are directly released in the blood stream.

Question 4. 
What do you mean by secondary sexual characters?
Answer:
Such features which help to distinguish the male from the female are called secondary sexual characters.

Question 5. 
Which hormone is helpful in the development of milk secreting glands in breasts? 
Answer:
The hormone secreted by pituitary gland is helpful in this work.

Question 6. 
What is meant by menarche? 
Answer:
The first menstrual flow begins at puberty is termed as menarche.

Question 7. 
What is menopause?
Answer:
Stoppage of menstruation is termed as menopause. In ladies at 40 to 45 years of age, the menstrual cycle stops.

Question 8. 
Which controls the menstruation cycle? 
Answer:
Menstruation cycle is controlled by hormone.

Question 9. 
Write the activities taking place in menstruation cycle.
Answer:

1. Ova begins to mature 
2. Release of ova 
3. wall of uterus becomes thick
4. If fertilization does not occur, it is shed off. 

Question 10. 
Is mother responsible for the sex of her child?
Answer:
Sex chromosome of the father determines the boy or girl. Mother is not responsible for this.

Question 11. 
Where is thyroid gland present? Write the name of its secretory hormone.
Answer:
Thyroid gland is present in neck. It secretes the thyroxine hormone.

Question 12. 
Which hormone maintains the correct salt balance in the blood?
Answer:
By means of adrenalin hormone.

Short Answer Type Questions

Question 1. 
What do you mean by teenagers? 
Answer:
Adolescents are also called teenagers since this perioid covers the teen (13 to 18 or 19 years of age). Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age. In girls adolescence may begin a year or two earlier than in boys.

Question 2. 
How does their height grow at the time of puberty? Explain.
Answer:
In boys and girls several changes takes place at the time of puberty. Among them increase in height is also a change. During this there is sudden increase in height which we can see. At this time the long bones, that is, the bones of the arms and the legs elongate and make a person tall. Initially, girls grow faster than boys but by about 18 years of age, both reach their maximum height. The rate of growth in height varies in different individuals. Some may grow suddenly at puberty and then slow down, while others may grow gradually.

Question 3. 
What are the changes takes place in body shape at the time of puberty?
Answer:
At the time of puberty fast changes take place in shoulders and chest. Shoulders generally broaden. In girls, the region below the waist becomes wider. In boys, the muscles of the body grow more prominenty than in the girls. 

Question 4. 
Voice change at the time of puberty. Why?
Answer:
At puberty, the voice box or the larynx begins to grow. Boys develop larger voice boxes. The growing voice box in boys can be seen as a protruding part of the throat called Adam's apple. In girls the voice box comparatively small so hardly visible. Generally, girls have a high pitched voice, whereas boys have a deep voice. In adolescent boys, sometimes, the muscles of the growing voice box go out of control and the voice becomes hoarse. This state may remain for a few days or weeks and after that the voice becomes normal.

Question 5. 
How does development in reproductive organs occur during puberty? 
Answer:
At the beginning of puberty, the male genital organs such as the testes and penis develop. The production of sperm from the testes also starts in girls, the size of the ovaries increases and the eggs begin to mature. Release eggs from the ovaries also starts.

Question 6. 
How do the adolescents feel in adolescence? 
Answer:
Adolescence is also a period of changes in a person’s way of thinking. Adolescents are more independent than before and are also self conscious. Intellcutual development takes place and they tend to spend considerable time thinking. In fact, it is often the time in one’s life when the brain has the greatest capacity for learning. Sometimes, however, an adolescent may feel insecure while trying to adjust to the changes in the body and mind, but as adolescent learners, they should know that there is no reason to feel insecure. These changes are natural for their growth.

Question 7. 
Clearly differentiate between menstruation and menarche.
Answer:
Menstruation:
In ladies if egg is not fertilized, the released egg, and the thickened lining of uterus along with its blood vessels are shed off. This causes bleeding in women which is called menstruation.
Menarche:
Menstruation occurs once in about 28 to 30 days. The first menstrual flow begins at puberty and is termed menarche.

Question 8. 
"If any girl looks a boy at the time of menstruation she becomes pregnant." Give your clear opinion on this statement. Answer:
Above statement is false. We know that in reproduction process there is help of male reproductive organ and female reproductive organ. During reproduction sperm comes in contact with an egg and fuse, which we say fertilization. In absence of this any girl can't be pregnant. So above statement is totally false. 

Question 9. 
Name the male sexual hormone and explain two important functions.
Answer:
The name of male sexual hormone is testosterone. It is secreted by testes. Its main functions are:

1. Production of male gamete 'sperms'.
2. It controls in male accessory sexual organs and secondary sexual characters as moustaches, beard and voice develop.

Question 10. 
Name the female sexual hormone and explain its functions.
Answer:
Estrogen is the female sexual hormone. 

Functions of estrogen:

1. Control on production of female gamete (egg).
2. Control on accessory sexual organ and secondary sexual characters as - breast glands, hair formation and voice.

Question 11. 
When and how the reproductive period is decided in humans?
Answer:
In human adolescents become capable of reproduction when their testes and ovaries begin to produce gametes. In females, the reproductive phase of life begins at puberty (10 to 12 years of age) and generally lasts till the age of approximately 45 to 50 years. The ova begins to mature with the onset of puberty. One ovum matures and is 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 fertilised it begins to develop. It results in pregnancy. The capacity for maturation and production of gametes lasts for a much longer time in males than in females.

Question 12. 
What is the role of hormones in completing the life cycle of insects and frogs?
Answer:
We know that in life cycle of insects and frog there are many stages. Similarly, the tadpole passes through certain stages to become a frog. This change from larva to adult is called metamorphosis. Metamorphosis in insects is controlled by insect hormones. In a frog, it is controlled by thyroxine, the hormone produced by thyroid. Thyroxine production requires the presence of iodine in water. If the water in which the tadpoles are growing does not contain sufficient iodine, the tadpoles cannot become adults.

Question 13. 
Differentiate between estrogen and testosterone. 
Answer:

Estrogen	Testosterone
1. This is the female hormone, secreted by ovary.	1. This is the male hormone, secreted by testes.
2. This hormone develops the secondary female characters, as development of breasts.	2. This hormone develops the secondary male characters, as beard, moustaches grow.

Question 14. 
What is the significance of personal hygiene and physical exercise in our life? 
Answer:
To pay attention on personal hygiene in our life is very necessary. Everyone should have a bath atleast once everyday to increase activity of sweat glands. They sometimes make the body smelly. All parts of the body should be washed and cleaned everyday. If cleanliness is not maintained there are chances of catching bacterial infection. Girls should take special care of cleanliness during the time of menstrual flow. They should keep track of their menstrual cycle and be prepared for the onset of menstruation.

Physical exercise: Walking and playing in fresh air keeps the body fit and healthy. All young boys and girls should take walks, exercises and play outdoor games.

Question 15. 
Write about the myths and notions of adolescents.
Answer:
In adolescents some below mentioned false notions, are myths and not facts:

1. A girl becomes pregnant if she looks at boys during menstruation.
2. The mother is responsible for the sex of her child.
3. A girl should not be allowed to work in the kitchen during menstruation.

Question 16. 
Adolescent should say 'No' to drugs, why?
Answer:
Adolescence is a period of much activity in the body and mind which is a normal process of growth. So do not feel confused or insecure. If anybody suggests that you wall get relief if you take some drugs, just say ‘No’ unless it is prescribed by the doctor. Drugs are addictive. If you take them once, you feel like taking them again and again. They harm the body in the long run. They ruin health and happiness. 

Question 17. 
What is AIDS? How is spread? 
Answer:
Acquired Immuno Deficiency Syndrome is the full name of AIDS. Due to this there is the loss of immunity of our body. AIDS is caused by HTV virus. This virus can pass on to a normal person from an infected person by sharing the syringes used for injecting drugs. It can also be transmitted to an infant from the infected mother through her milk. The virus can also be transmitted through sexual contact with a person infected with HIV.

Question 18. 
What will be the effect on the body if pituitary gland is removed before puberty?
Answer:
Pituitary gland secretes many hormones. One of these hormones also stimulates testes and ovaries to produce their hormones, which are essential for fertility development. It also secretes growth hormone which is necessary for the normal growth of the body. Such hormones are also secreted by the pituitary gland which control the function of other endocrine glands. Therefore, if the pituitary gland is removed before puberty, the normal growth of the body as well as reproductive capacity will be blocked.

Essay Type Questions

Question 1. 
How is the sex determination process in offspring? Explain.
Answer:
Inside the fertilized egg or zygote is the instruction for determining the sex of a baby. In this process sex chromosome helps. We know that all human beings have 23 pairs of

chromosomes in the nuclei of their cells. Two chromosomes (1 pair) out of these are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only one set of chromosomes. The unfertilized egg always has one X chromosome. But sperms are of two kinds. One kind has a X chromosome, and the other kind has a Y chromosome. When a sperm containing X chromosome fertilises the egg, the zygote would have two X chromosomes and develop into a female child. If the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote would develop into a male child.

Question 2. 
Draw a diagram showing the position of different endocrine glands in the human. Describe the function of hormones which are secreted by these glands.
Answer:
Endocrine Glands:
1. Pituitary gland:
It is situated at the lower part of our head. Its size is like the grain of pea. Hormone secreted by it controls the function of other endocrine glands.


2. Thyroid glands:
This gland is situated at the base on the both sides of respiratory tube. It secrete the thyroxine hormone, it is formed by iodine. By deficiency of this hormone 'goitre' disease develop, by this throat become bulged.

3. Adrenal gland:
This gland is situated on upper part of kidney. It secretes adrenalin hormone. It maintains the correct salt balance in the blood. It helps the body adjust stress when one is very angry, embarrassed or worried.

4. Pancreas gland:
It is situated below stomach. It secretes insulin hormone. It controls the quantity of glucose in blood. Due to deficiency of this hormone glucose comes out with urine, to which we call diabetes disease.

5. Reproductive glands:
They produce reproductive hormones which are responsible for maturation of sex organs and secondary sexual characters.
They are of two types:
(a) Female reproductive glands 
(b) Male reproductive glands.

(a) Female reproductive glands:
Ovary: it produces estrongen and progesteron hormones, which is responsible for female secondary sexual characters.

(b) Male reproductive glands: It secrete testosterone hormone, which is responsible for male secondary sexual characters.

Question 3. 
What is the nutritional requirement of adolescents? Explain.
Answer:
Adolescence is a state of rapid growth and development. Hence the diet for an adolescent has to be carefully planned. In this stage we should take balanced diet in which proteins, carbohydrates, fats, vitamins and minerals are present in requisite proportions. Our Indian meal of roti, rice, dal and vegetables is a balanced meal. Milk is a balanced food in itself.

Fruits also provide nourishment. Iron builds blood and iron rich food such as leafy vegetables, jaggery, meat, citrus, Indian gooseberry (amla) are good for adolescents. Our lunch and dinner include cereals which give energy. We can also include milk, meat, nuts and pulses. Besides them it is also essential to include fats and sugar which are the source of energy. Use of fruits and vegetables is essential as protective foods. We should avoid the use of packed or tinned food materials because they do not have adequate nutritional value.