Samacheer Kalvi 8th Science Book Back Answers Chapter 20

Samacheer Kalvi 8th Science Book Back Question and Answers:

Samacheer Kalvi 8th Standard Science Book Back 1 Mark and 2 Mark Question & Answers PDF uploaded and available below. Class 8 New Syllabus 2022 to 2023 Book Back Questions & Answers/solutions available for both English and Tamil Medium. Class 8 std Science Book Chapter 20 – Reaching the Age of Adolescence Science Answers/Solutions Guide are uploaded on this page. 8th standard Science Book is consists of 23 Units. All 23 chapters of Science Book Back One, and Two Mark Solutions are given below.

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8th Science Book Back Chapter 20 Solutions Guide PDF:

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8th Science Chapter – 20

Reaching the Age of Adolescence – Book Back Answers

I. Choose the best answer.

1. Adolescence is the period of life between ……………… years of age.
(a) 10 to 16
(b) 11 to 17
(c) 11 to 19
(d) 11 to 20
Answer: (c) 11 to 19

2. The period at which an organism attains sexual maturity is called ………………
(a) puberty
(b) adolescence
(c) growth
(d) maturity
Answer: (a) puberty

3. During puberty, the region below the waist become wider in ………………
(a) boys
(b) girls
(c) Both a and b
(d) None of these
Answer: (c) Both a and b

4. Adam’s apple is the growth of the ………………
(a) pharynx
(b) thyroid
(c) larynx
(d) parathyroid
Answer: (c) larynx

5. Many adolescent boys and girls get pimples on face, due to the secretions of ……………… gland.
(a) sweat
(b) sebaceous
(c) sweat and sebaceous
(d) None of these
Answer: (b) sebaceous

6. The sperm is produced by ………………
(a) penis
(b) ovary
(c) uterus
(d) testes
Answer: (d) testes

7. …………. are the chemical substances, secreted by endocrine glands.
(a) Hormones
(b) Enzymes
(c) Proteins
(d) Fatty acids
Answer: (a) Hormones

8. Androgen production is regulated by ………………
(a) GH hormone
(b) LH hormone
(c) TSH hormone
(d) ACTH hormone
Answer: (b) LH hormone

9. During menstruation, the progesterone level is ………………
(a) decreased
(b) increased
(C) ceased
(d) normal
Answer: (a) ceased

10. ……………… intake needs to be increased to prevent osteoporosis in later life.
(a) Potassium
(b) Phosphorus
(c) Iron
(d) Calcium
Answer: (d) Calcium

II. Fill in the blanks:

……………… is secreted by the ovaries of female.
The hormones secreted by the gonads are controlled by ………………
Milk secretion during lactation is controlled by ……………… hormone.
The male and the female gamete fuse together and form ……………….
The first menstrual flow begins at puberty and it is termed as ………………
……………… usually occurs 14 days after ovulation.
……………… includes protein, carbohydrates, fats and vitamins in requisite proportion.
……………… helps to prevent thyroid gland related diseases.
Iron deficiency leads to ………………
In women, fertilization takes place at ……………….

Answer:

Estrogen
Anterior pituitary
prolactin
zygote
menarche
Menstruation
Balanced diet
iodine
Anaemia
Fallopian tube

III. State True or False. If false, correct the statement

1. There is a sudden increase in the height of both boys and girls during puberty.
Answer: True.

2. The release of ovum from the uterus is called ovulation.
Answer: False

3. During pregnancy, the corpus luteum continues to grow and produces large amount of estrogen and progesterone.
Answer: True

4. Making use of disposable napkins or tampons may increase the chances of infections.
Answer: False
Correct statement:
Making use of disposable napkins or tampons may reduce the chances of infections.

5. Using clean toilets for defecation is a good practice.
Answer: True

IV. Match the following

Question 1.

Puberty – Testosterone
Adam’s apple – Muscle development
Androgen – at 45 to 50 years of age
ICSH – Sexual maturity
Menopause – Change in voice

Answer:

Puberty – Sexual maturity
Adam’s apple – Change in voice
Androgen – Muscle development
ICSH – Testosterone
Menopause – at 45 to 50 years of age

V. Answer briefly

1. What is adolescence?
Answer:

The term adolescence is derived from the Latin word ‘adolescere’ meaning ‘to grow’ or ‘grow to maturity’.
Biologically it is a physical transition marked by the onset of puberty and termination of physical growth in an individual.

2. List out the changes which occur during puberty.
Answer:
Puberty transform the body of a child into that of an adult. These changes are:

Changes in body size
Changes in body proportion
Development of primary sex characteristics
Development of secondary sex characteristics.

3. What is secondary sex characteristics?
Answer:
Secondary sex characteristics are the physical features which distinguish male from female.

4. What is fertilization?
Answer:
The fusion of the sperm and egg is called fertilization.

5. Explain Menarche.
Answer:

The first menstrual flow begins at puberty and is termed menarche.
It is the beginning of adolescence, during which mental and emotional maturation occurs and physical growth becomes pronounced.

6. Explain the process of pregnancy.
Answer:

After ovulation, the ovum reaches the fallopian tube and fertilization takes place.
The fertilized egg undergoes development and it is implanted in the uterus.
The corpus luteum continues to grow and produces large amount of progesterone.
This results in pregnancy. Normally, it lasts for 280 days, at the end of which parturition (child birth) takes place.

7. Explain the importance of cleanliness during the time of menstrual cycle in girls.
Answer:

Girls should take special care of cleanliness during the time of menstrual cycle.
Making use of disposable napkins or tampons may reduce chances of infections. It should be changed frequently depending upon the menstrual flow.

8. How is adolescence different from childhood?
Answer:

The period of life from birth till 12 years is also childhood. Adolescence begins from age of 12 -13 years.
Lot of changes in height, weight, sex organs, muscle mass etc, occur in adolescence.