Reaching the Age of Adolescence — Class 8 Science NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 8 Science chapter "Reaching the Age of Adolescence" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 8 Science chapter "Reaching the Age of Adolescence" — 8 important questions with detailed answers for CBSE…
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NCERT Solutions for Class 8 Science — Reaching the Age of Adolescence. Step-by-step answers to all 8 textbook questions from this chapter, written for CBSE board preparation and free to use.
Reaching the Age of Adolescence — All 8 Questions Solved
Q1. What is adolescence?
Adolescence is the transitional stage of physical and psychological development between childhood and adulthood, typically occurring from 11-18 years. Marked by rapid growth, development of secondary sexual characteristics, and emotional changes.
Q2. What are primary sex characteristics?
Primary sex characteristics are organs directly involved in reproduction: testes and penis in males, ovaries and uterus in females. They are present at birth and are essential for sexual reproduction.
Q3. Define secondary sex characteristics and list five in males.
Secondary sex characteristics are physical features that develop during puberty, not directly involved in reproduction. Five in males: 1) Facial hair growth, 2) Deep voice due to larynx enlargement, 3) Increased muscle mass, 4) Broadened shoulders, 5) Body hair on chest and limbs.
Q4. What are the secondary sex characteristics in females?
Secondary sex characteristics in females: 1) Breast development, 2) Broadening of pelvis/hips, 3) Appearance of body hair (axilla, pubic area), 4) Higher-pitched voice remains, 5) Menstruation begins, 6) Increased fat deposition in breasts/hips.
Q5. What is the role of testosterone and estrogen?
Testosterone: male hormone produced by testes, stimulates development of male secondary characteristics, increases muscle growth, deepens voice. Estrogen: female hormone produced by ovaries, stimulates development of female secondary characteristics, regulates menstrual cycle, maintains pregnancy.
Q6. What is menstruation and what is its significance?
Menstruation is the monthly shedding of the uterine lining (endometrium) in females, occurring approximately every 28-30 days. It prepares the uterus for pregnancy; if fertilization doesn't occur, the lining is shed. Average duration: 3-5 days.
Q7. What are the common health issues during adolescence?
Health issues: 1) Acne and skin problems (hormonal), 2) Body odor (increased sweat), 3) Mood swings and emotional stress, 4) Insomnia or irregular sleep, 5) Poor nutrition habits, 6) Body image concerns. Proper hygiene, balanced diet, and sleep address most issues.
Q8. What is personal hygiene during adolescence?
Personal hygiene practices: 1) Daily bathing with clean water and soap, 2) Wash hands before eating and after toilet, 3) Trim nails regularly, 4) Brush teeth twice daily, 5) Wash hair regularly, 6) Change underclothes daily, 7) Maintain clean surroundings. Prevents infections and disease transmission.
Reaching the Age of Adolescence — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. What is the period of life, when the body undergoes changes, leading to reproductive maturity, called?
- A. Childhood
- B. Adolescence
- C. Adulthood
- D. Infancy
Answer: B. Adolescence — Adolescence is the period during which the body undergoes changes leading to reproductive maturity, typically beginning around 10-11 years of age.
MCQ 2. In humans, adolescence generally begins around the age of:
- A. 5-6 years
- B. 10-11 years
- C. 20-22 years
- D. 30-35 years
Answer: B. 10-11 years — Adolescence typically starts around 10-11 years of age and lasts up to 18 or 19 years of age.
MCQ 3. Which of the following is a primary change that marks the onset of puberty in boys?
- A. Deepening of voice
- B. Growth of hair under armpits
- C. Development of testes and production of sperm
- D. Increase in height
Answer: C. Development of testes and production of sperm — The development of reproductive organs and the production of gametes (sperm in males) are the primary changes indicating reproductive maturity and the true onset of puberty.
MCQ 4. The male hormone responsible for secondary sexual characteristics is:
- A. Estrogen
- B. Insulin
- C. Adrenaline
- D. Testosterone
Answer: D. Testosterone — Testosterone is the male hormone produced by the testes, responsible for the development of male secondary sexual characteristics like facial hair and deepening voice.
MCQ 5. Which gland secretes hormones that stimulate the testes and ovaries to produce their respective hormones?
- A. Thyroid gland
- B. Pancreas
- C. Pituitary gland
- D. Adrenal gland
Answer: C. Pituitary gland — The pituitary gland, often called the master gland, secretes hormones that stimulate the gonads (testes and ovaries) to release their hormones, initiating puberty.
MCQ 6. The female hormone responsible for the development of breasts and other female secondary sexual characteristics is:
- A. Testosterone
- B. Estrogen
- C. Progesterone
- D. Thyroxine
Answer: B. Estrogen — Estrogen is the female hormone produced by the ovaries, primarily responsible for the development of female secondary sexual characteristics.
MCQ 7. The voice box in boys often develops into a prominent part called the:
- A. Larynx
- B. Pharynx
- C. Adam's apple
- D. Trachea
Answer: C. Adam's apple — The growing larynx (voice box) in boys often becomes visible as a protruding part in the neck, known as the Adam's apple.
MCQ 8. What is the process called when a mature ovum is released from the ovary?
- A. Menstruation
- B. Fertilization
- C. Ovulation
- D. Implantation
Answer: C. Ovulation — Ovulation is the process of releasing a mature egg (ovum) from the ovary. Menstruation is the shedding of the uterine lining, and fertilization is the fusion of sperm and ovum.
MCQ 9. The first menstrual flow in a girl is termed as:
- A. Menopause
- B. Menarche
- C. Ovulation
- D. Puberty
Answer: B. Menarche — The first menstrual flow, which occurs at puberty, is termed menarche. Menopause is the cessation of menstruation.
MCQ 10. During adolescence, increased activity of sweat glands can lead to:
- A. Acne
- B. Body odour
- C. Hair growth
- D. Deepening of voice
Answer: B. Body odour — Increased activity of sweat glands during adolescence produces more sweat, which can cause body odour if proper hygiene is not maintained.
MCQ 11. Acne and pimples are common in adolescents due to increased activity of:
- A. Sweat glands
- B. Salivary glands
- C. Sebaceous glands
- D. Thyroid glands
Answer: C. Sebaceous glands — The increased activity of sebaceous (oil) glands during adolescence leads to more oil secretion, which can clog pores and cause acne and pimples.
MCQ 12. An adolescent's diet should ideally include more of:
- A. Fats and refined sugars
- B. Chips and aerated drinks
- C. Proteins, fruits, vegetables, and whole grains
- D. Only carbohydrates
Answer: C. Proteins, fruits, vegetables, and whole grains — Adolescents are in a phase of rapid growth and development, requiring a balanced diet rich in proteins, vitamins, minerals, and complex carbohydrates for optimal health.
MCQ 13. Which chromosomes are present in a female human being?
- A. XY
- B. XX
- C. YY
- D. XYY
Answer: B. XX — A human female has two X chromosomes (XX) in her cells, while a human male has one X and one Y chromosome (XY).
MCQ 14. The sex of the baby is determined by the chromosomes of the:
- A. Mother
- B. Father
- C. Grandparents
- D. Both mother and father equally
Answer: B. Father — The sex of the baby is determined by the father's sperm. If it carries an X chromosome, the baby will be a girl (XX); if it carries a Y chromosome, the baby will be a boy (XY).
MCQ 15. Where does fertilization typically occur in humans?
- A. Uterus
- B. Ovary
- C. Fallopian tube (Oviduct)
- D. Vagina
Answer: C. Fallopian tube (Oviduct) — Fertilization, the fusion of sperm and ovum, typically takes place in the oviduct, also known as the fallopian tube.
MCQ 16. The permanent cessation of menstruation in women is known as:
- A. Menarche
- B. Ovulation
- C. Menopause
- D. Puberty
Answer: C. Menopause — Menopause is the natural biological process that marks the end of a woman's reproductive years, usually occurring around 45-50 years of age.
MCQ 17. Glands that release hormones directly into the bloodstream are called:
- A. Exocrine glands
- B. Salivary glands
- C. Endocrine glands
- D. Digestive glands
Answer: C. Endocrine glands — Endocrine glands are ductless glands that secrete hormones directly into the bloodstream to reach target organs throughout the body.
MCQ 18. Which of the following is the correct sequence of hormone action initiating puberty?
- A. Gonads → Pituitary → Hormones
- B. Pituitary → Gonads → Hormones
- C. Hormones → Pituitary → Gonads
- D. Gonads → Hormones → Pituitary
Answer: B. Pituitary → Gonads → Hormones — The pituitary gland secretes hormones that stimulate the testes and ovaries (gonads) to release their respective hormones (testosterone and estrogen), initiating puberty.
MCQ 19. During adolescence, individuals often experience periods of insecurity and self-consciousness because:
- A. They are suddenly very strong.
- B. Their body is undergoing rapid physical changes.
- C. They are no longer growing.
- D. They have too many friends.
Answer: B. Their body is undergoing rapid physical changes. — The rapid and sometimes uneven physical changes during adolescence can make individuals feel awkward or insecure about their changing appearance, leading to self-consciousness.
MCQ 20. Which of these is a secondary sexual characteristic in girls?
- A. Growth of facial hair
- B. Deepening of voice
- C. Development of breasts
- D. Broadening of shoulders
Answer: C. Development of breasts — Development of breasts is a prominent secondary sexual characteristic that develops in girls during puberty, due to the action of estrogen.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.