Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

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Tamilnadu Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

Samacheer Kalvi 8th Science Reaching the Age of Adolescence Text Book Exercises

I. Choose the best answer.

Question 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

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

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

Question 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

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

Question 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

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

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

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

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

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

Question 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

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

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

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

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

Question 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.

Question 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

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

Question 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.

Question 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.

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

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

Question 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.

Question 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.

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

Question 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.

Question 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.

VI. Answer in detail

Question 1.
What are the physical changes that occur in boys and girls during adolescence?
Answer:
Secondary sex characteristics are the physical features which distinguish male from female. The Physical changes that occur is boys and girls during adolescence are:

Girls:

  1. Height and weight increase.
  2. Fatty and subcutaneous tissues develop.
  3. Hip broadens.
  4. Hair grows in arm pits and pubic area.
  5. Voice becomes shrill.
  6. Breast develops.

Boys

  1. Height and weight increase.
  2. Muscles develop.
  3. Shoulder broadens.
  4. Hair grows in the arm pits and pubic area, and facial hair also appears.
  5. Voice break takes place due to lengthening of vocal cord and enlarging of larynx.
  6. Size of the penis increases.

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

Question 2.
Explain the role of hormones in reproduction.
Answer:

  1. The primary hormones that regulate reproduction are the steroids such as androgens, estrogens and progesterone. which have masculinizing, feminizing and gestational effects respectively.
  2. These hormones are secreted from the gonads which are regulated by the anterior pituitary (adenohypophysis).

Follicle Stimulating Hormone (FSH):
FSH in a female influences the development of the Graafian follicle and secretion of estrogens. In a male, it is necessary for the development of seminiferous tubules, and for spermatogenesis.

Luteinizing Hormone (LH):
In a female, it is the hormone necessary for ovulation, and the secretion of the luteal hormone progesterone, and for the final maturation of the Graafian follicle. In a male, it stimulates the interstitial (Leydig) cells of testes and the secretion of testosterone, and is referred to as the Interstitial Cell Stimulating Hormone (ICSH).

Prolactin (PRL) or Lactogenic Hormone:
The main function of this hormone is milk secretion during lactation.

Oxytocin Hormone:
Oxytocin causes expulsion of milk from the breast and it is also involved in the contraction of smooth muscles of uterus during child birth.

Question 3.
Briefly describe the menstrual cycle.
Answer:
The beginning of the menstrual cycle marks the onset of puberty in human females. Menstruation occurs if an ovum released by the ovary of a woman is not fertilized during ovulation. This is described below.

1. When a girl reaches puberty at the age of about 10, the sex hormones released into her blood cause some of the ova (or egg cells) in her ovaries to become mature (or ripe).

2. Usually one mature ovum (or egg) is released ff(jm one of the ovaries into the oviduct once in every 28 days. This is called ovulation.

3. Before ovulation (or release of ovum), the inner wall of uterus becomes thick and spongy, and full of tiny blood vessels to receive the fertilized ovum.

4. If the ovum does not get fertilized then the thick and soft inner lining of uterus breaks. So, the thick and soft inner lining of uterus along with the blood vessels and the dead ovum comes out of the vagina in the form of a bleeding called menstruation.

5. Menstruation usually occurs 14 days after ovulation and usually lasts for about 3 to 5 days.

6. After menstruation is over, the inner lining of the uterus starts building up again so that it may become ready to receive the next ovum.

7. If the ovum does not get fertilized even now, then menstruation takes place again. This cycle of menstruation is repeated again and again in women after every 28 days. The menstrual cycle is controlled by hormones.

Menstruation stops temporarily when the ovum gets fertilized and the women gets pregnant. Menstruation also stops due to nutritional deficiencies, low body weight, stress, eating disorder, excessive weight gain etc.

Question 4.
Briefly explain the nutritional needs of adolescence.
Answer:

  1. Adolescence is a stage of rapid growth and development.
  2. Balanced diet is very much important during adolescence. Balanced diet includes proteins, carbohydrates, fats and vitamins in requisite proportions.
  3. A very good amount of proteins and carbohydrates is necessary during this growth period. Apart from that, adolescents need the following dietary components.

Minerals:

  1. Since there is an increase in skeletal mass and blood volume during adolescence, the body needs calcium, phosphorus and iron.

Calcium:

  1. Calcium intake needs to be increased to prevent osteoporosis in later life.
  2. It is present in milk and milk products or other equivalents.

Iodine:

  1. It helps to prevent thyroid gland related diseases.

Iron:

  1. Iron builds blood and iron-rich foods such as green leafy vegetables, jaggery, meat, dates, fish, chicken, citrus, Indian gooseberry (Nelli) and whole pulses are good for adolescents.
  2. Lack of iron in the diet results in anemia.
  3. In boys, iron deficiency occurs due to muscle spurt whereas in girls it occurs due to menstruation in addition to the muscular growth.

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

VII. Higher Order Thinking Questions.

Question 1.
What can you suggest to your classmates to keep himself / herself clean and healthy?
Answer:

  1. Shower or bath daily.
  2. Always wash your hands before and after meals.
  3. Keep fingernails clean and dipped.
  4. Wash your teeth and mouth before and after each meal.
  5. Avoid touching your face, nose or mouth while preparing food.
  6. Avoid coughing or sneezing around food and close your mouth by using hand kerchief while you cough in public places.
  7. If you want to taste the food, use a clean spoon.
  8. Change your clothes regularly and wash them cleanly, especially undergarments.
  9. Do not defecate in open field. Use clean toilets for defecation.
  10. If you are not well, avoid self-medication, consult a doctor.
  11. In case of girls, menstrual hygiene can be explained to them.

Question 2.
Adolescence is the energistic stage. What health and good habits you want to develop?
Answer:
Healthy and good habits that we should develop during adolescence are:

  1. Eat balanced diet and avoid junk food to prevent obesity.
  2. Regular physical exercise which helps to build our body.
  3. Keep ourselves clean by bathing twice a day, cutting hair, trimming nails, wearing clean cloths.
  4. Keep away from abusive substances, drugs smoking and any other bad habits.
  5. Observe menstrual hygiene.
  6. Be aware of problems related to adolescence and take care of one’s physical and mental health.

Samacheer Kalvi 8th Science Reaching the Age of Adolescence Additional Questions

I. Choose the correct answer

Question 1.
………………. is not a source of iron.
(a) Gooseberry
(b) Fish
(c) Milk
(d) Jaggery
Answer:
(c) Milk

Question 2.
FSH is produced by ………………..
(a) pituitary gland
(b) thyroid gland N
(c) uterus
(d) testes
Answer:
(a) pituitary gland

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

Question 3.
ICSH refers to ………………..
(a) FSH
(b) LH
(c) oxytocin
(d) testosterone
Answer:
(b) LH

Question 4.
Menstruation normally occurs once in ……………….
(a) 25 days
(b) 35 days
(c) 28 days
(d) 19 days
Answer:
(c) 28 days

Question 5.
Normally pregnancy lasts for ………………. days.
(a) 300
(b) 280
(c) 320
(d) 260
Answer:
(b) 280

II. Fill in the Blanks

  1. Oil glands are called ………………. glands.
  2. The primary sex organs of the male and female are called ………………. and ………………. respectively.
  3. ………………. hormone stimulates the testes to produce androgens.
  4. ……………….. is the male sex hormone.
  5. The hormone ………………. is involved in the contraction of uterine muscles during child birth.
  6. The release of ovum from the ovary is called ………………..
  7. The wall of ………………. becomes thick to receive the fertilized egg.
  8. Fertilization takes place in the ………………..
  9. ………………. is a temporary endocrine gland formed during pregnancy.
  10. Stoppage of menstruation is called ………………..

Answer:

  1. sebaceous
  2. Testes, ovary
  3. Leutinizing
  4. Androgen
  5. oxytocin
  6. ovulation
  7. uterus
  8. Fallopian tube
  9. Corpus luteum
  10. menopause

III. True or False – if false give the correct statement.

Question 1.
The male sex hormone is called estrogen.
Answer:
False.
Correct statement:
The male sex hormone is called androgen.

Question 2.
Prolactin is also known as lactogenic hormone.
Answer:
True.

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

Question 3.
The FSH is required for spermatogenesis in males.
Answer:
True.

Question 4.
Milk is rich in calcium.
Answer:
True.

Question 5.
In take of iodine is necessary to prevent anemia.
Answer:
False.
Correct statement:
In take of iron is necessary to prevent anemia.

Question 6.
Corpus luteum grows during menstruation.
False.
Correct statement:
Corpus luteum degenerates during menstruation.

Question 7.
Egg is released from fallopian tube.
Falsw.
Correct statement:
Egg is released from ovary.

IV. Match the following

Question 1.

1. Calcium (a) Salt
2. Iron (b) Fruits
3. Iodine (c) Jaggery
4. Minerals (d) Pulses
5. Protein (e) Milk

Answer:

  1. e
  2. e
  3. a
  4. b
  5. d

V. Answer briefly

Question 1.
Name the sex organs and their hormones.
Answer:
The male sex glands testes release the testosterone and the female sex gland, the ovaries release the estrogen.

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

Question 2.
Name the pituitary hormones which influence the gonads (sex organs).
Answer:
Follicle stimulating hormone, Luteinizing hormone and oxytocin.

Question 3.
Define ovulation.
Answer:
The release of ovum from the ovary is called ovulation.

Question 4.
When does the corpus luteum degenerate?
Answer:
If the ovum is not fertilized the corpus luteum begins to degenerate.

Question 5.
What is menopause?
Answer:
Menopause marks the end of the reproductive phase of a woman’s life. At 45 to 50 years of age, the menstrual cycle stops.

Question 6.
What is menstruation?
Answer:

  1. If the ovum is not fertilized, the corpus luteum begins to degenerate and the production of hormones progesterone and estrogen ceases.
  2. The unfertilized egg and the thickened lining of the uterus along with its blood vessels are shed off.
  3. This causes bleeding in woman’s reproductive tract which is called menstruation.

VI. Answer in detail.

Question 1.
Explain the Secondary sex characteristics of Boys.
Answer:
the following are the secondary sex characteristics of boys.

  1. Hair – Immediately after the development of primary sex characteristics, pubic hair appears followed by axillary and facial hair.
  2. Skin – The skin becomes coarse and the pores in the skin enlarge.
  3. Glands – The oil producing glands in the skin enlarge and due to this acne may appear of the faces.
  4. Muscle – The strength of the muscle increases and it gives shape to arms, legs and shoulders.
  5. Voice – During this period voice changes occur and the voice becomes husky. Then its pitch drops and the volume increases.

Samacheer Kalvi 8th Science Solutions Term 2 Chapter 6 Reaching the Age of Adolescence

Question 2.
Explain the Secondary sex characteristics of Girls.
Answer:
Girls show the following secondary sex characteristics at the time of puberty.

  1. Hips – Due to the enlargement of the pelvic bone and the development of subcutaneous fat, the hip becomes wider and rounder.
  2. Breast – After the enlargement of hips, the breasts begin to develop during this time.
  3. Hair – Pubic hair appears followed by axillary and body hair on the limbs.
  4. Skin – The skin becomes coarser and the pores enlarge as in the case of boys.
  5. Gland – Oil producing glands become active causing acne on the face.
  6. Muscles – Increase in muscles takes place which gives shape to shoulders, arms and legs.
  7. Voice – Voice becomes shrill and voice breaks are rare among girls.

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