Samacheer Kalvi 8th Science Unit 20 Book Back Answers:

Samacheer Kalvi 8th Standard New Science Book Back 1 Mark and 2 Mark Question & Answers PDF uploaded and available below. Class 8 New Syllabus 2021 to 2022 Book Back Question & Answer available for both English and Tamil Mediums. Class 8th Science Book Unit 20 – Reaching the age of Adolescence Answers/Solutions are provided on this page. 8th Std Science Book consists of 23 units, All Science Book Back One, and Two Mark Solutions are given below.

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Samacheer Kalvi 8th Science Book Back Solutions PDF:

8th Science Subject 1 Mark and 2 Mark Solutions PDF available below. Click the Download option to download the book back 1 Mark & 2 Mark questions and answers. Take the printout and use it for exam purposes. Samacheer Kalvi 8th Science Unit 20 Answers are given below.

Science Book Back Answers

Unit 20 – Reaching the Age of Adolescence

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:

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

Answer:

1. Estrogen
2. Anterior pituitary
3. prolactin
4. zygote
5. menarche
6. Menstruation
7. Balanced diet
8. iodine
9. Anaemia
10. 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.

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

Answer:

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

V. Answer briefly

1. What is adolescence?
Answer:

1. The term adolescence is derived from the Latin word ‘adolescere’ meaning ‘to grow’ or ‘grow to maturity’.
2. 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:

1. Changes in body size
2. Changes in body proportion
3. Development of primary sex characteristics
4. 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:

1. The first menstrual flow begins at puberty and is termed menarche.
2. 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:

1. After ovulation, the ovum reaches the fallopian tube and fertilization takes place.
2. The fertilized egg undergoes development and it is implanted in the uterus.
3. The corpus luteum continues to grow and produces large amount of progesterone.
4. 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:

1. Girls should take special care of cleanliness during the time of menstrual cycle.
2. 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:

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

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