Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
I. Choose the Best Answer (MCQs)
Q1. Adolescence is the period between
- (a) Birth and childhood (b) Childhood and adulthood (c) Infancy and childhood (d) Adulthood and old age
Q2. The hormone that causes changes in boys during puberty is
- (a) Estrogen (b) Progesterone (c) Testosterone (d) Thyroxine
Q3. Menstruation occurs once in about
- (a) 15 days (b) 28 days (c) 35 days (d) 40 days
Q4. The pituitary gland is located at the base of the
- (a) Heart (b) Brain (c) Kidney (d) Liver
Q5. Dwarfism is caused by the under-secretion of
- (a) Thyroxine (b) Growth hormone (c) Insulin (d) Adrenaline
Q6. Adam's apple is caused by the enlargement of
- (a) Thyroid gland (b) Larynx (c) Pharynx (d) Trachea
Q7. Which of the following is a secondary sexual characteristic in girls?
- (a) Broad shoulders (b) Deep voice (c) Breast development (d) Facial hair
Q8. Goitre is caused by the deficiency of
- (a) Calcium (b) Iodine (c) Iron (d) Vitamin D
Additional MCQs
Q9. Which gland is called the master gland?
- (a) Thyroid (b) Adrenal (c) Pituitary (d) Pancreas
Q10. Insulin is secreted by
- (a) Thyroid gland (b) Pituitary gland (c) Adrenal gland (d) Pancreas
Q11. The sex of the foetus is determined by
- (a) Mother's egg (b) Father's sperm (c) Both mother and father (d) Hormones
Q12. The hormone adrenaline is secreted by
- (a) Pituitary gland (b) Thyroid gland (c) Adrenal gland (d) Pancreas
II. Fill in the Blanks
1. Adolescence is the period of life when the body undergoes changes leading to reproductive maturity. 2. The onset of reproductive maturity is called puberty. 3. Testosterone is the male hormone responsible for secondary sexual characteristics in boys. 4. Estrogen is the female hormone responsible for secondary sexual characteristics in girls. 5. The pituitary gland is called the master gland. 6. The thyroid gland produces the hormone thyroxine. 7. Deficiency of iodine causes goitre. 8. Insulin is secreted by the pancreas. 9. In females, the menstrual cycle occurs once in about 28 days. 10. Chromosomes are thread-like structures that carry genes. 11. The sex chromosomes in males are XY and in females are XX. 12. The voice box or larynx becomes larger in boys during puberty, forming the Adam's apple.
III. True or False
IV. Match the Following
Match 1:
| Column A | Column B | Answer |
|---|---|---|
| 1. Pituitary gland | (a) Emergency hormone | 1 — (e) Master gland |
| 2. Thyroid gland | (b) Diabetes | 2 — (d) Goitre |
| 3. Adrenal gland | (c) Growth hormone | 3 — (a) Emergency hormone |
| 4. Pancreas | (d) Goitre | 4 — (b) Diabetes |
| 5. Testes | (e) Master gland | 5 — (f) Testosterone |
Match 2:
| Column A | Column B | Answer |
|---|---|---|
| i. Testosterone | (a) Breast development | i — (c) Facial hair |
| ii. Estrogen | (b) Deep voice in boys | ii — (a) Breast development |
| iii. Thyroxine | (c) Facial hair | iii — (d) Metabolism regulation |
| iv. Insulin | (d) Metabolism regulation | iv — (e) Blood sugar regulation |
| v. Adrenaline | (e) Blood sugar regulation | v — (b) Fight-or-flight response |
Match 3:
| Column A | Column B | Answer |
|---|---|---|
| i. XX | (a) Male sex chromosomes | i — (c) Female sex chromosomes |
| ii. XY | (b) Menstrual cycle | ii — (a) Male sex chromosomes |
| iii. 28 days | (c) Female sex chromosomes | iii — (b) Menstrual cycle |
| iv. Larynx | (d) Master gland | iv — (e) Adam's apple |
| v. Pituitary | (e) Adam's apple | v — (d) Master gland |
V. Short Answer Questions
Q1. What is adolescence? Answer: Adolescence is the transitional period of growth and development between childhood and adulthood. It typically covers the ages from 11 to 19 years. During this period, the body undergoes significant physical, emotional, and hormonal changes that lead to reproductive maturity.
Q2. What is puberty? At what age does it begin in boys and girls? Answer: Puberty is the stage during adolescence when the reproductive organs become functional and secondary sexual characteristics begin to develop. In girls, puberty typically begins around 10-12 years of age. In boys, it usually starts around 12-14 years of age.
Q3. List any three secondary sexual characteristics in boys. Answer: 1. Growth of facial hair (beard and moustache) 2. Deepening of voice (voice box/larynx enlarges) 3. Development of broad shoulders and increased muscle mass
Q4. List any three secondary sexual characteristics in girls. Answer: 1. Development of breasts 2. Widening of hips 3. Onset of menstruation (menarche)
Q5. Why is the pituitary gland called the master gland? Answer: The pituitary gland is called the master gland because it controls and regulates the activity of most other endocrine glands in the body, including the thyroid, adrenal glands, and gonads (testes and ovaries). It secretes hormones like growth hormone, TSH, ACTH, FSH, and LH that direct other glands to release their hormones.
Q6. What is menstruation? Answer: Menstruation is the periodic discharge of blood, mucus, and the inner lining of the uterus (endometrium) through the vagina in females. It is part of the menstrual cycle, which repeats approximately every 28 days. The first occurrence of menstruation is called menarche, and the permanent stoppage is called menopause.
Q7. How is the sex of a baby determined? Answer: The sex of a baby is determined by the sex chromosomes present in the sperm that fertilizes the egg. Females have XX chromosomes (all eggs carry X), while males have XY chromosomes (sperm can carry X or Y). If an X-carrying sperm fertilizes the egg, the zygote is XX (female). If a Y-carrying sperm fertilizes the egg, the zygote is XY (male). Thus, the father's sperm determines the sex of the baby.
VI. Detailed Answer Questions
Q1. Describe the changes that take place during adolescence in boys and girls. Answer:
Adolescence brings about significant physical, emotional, and hormonal changes:
Changes in Boys: 1. Growth of facial hair (beard, moustache) and body hair (chest, underarms) 2. Deepening of voice due to enlargement of the larynx (Adam's apple forms) 3. Broadening of shoulders and increased muscle mass 4. Growth of the penis and testes 5. Production of sperm and onset of nocturnal emissions (wet dreams) 6. Rapid increase in height and weight 7. Increased activity of sweat and sebaceous glands (may cause acne)
Changes in Girls: 1. Development of breasts 2. Widening of hips 3. Growth of pubic hair and underarm hair 4. Onset of menstruation (menarche) 5. Growth of the uterus and ovaries 6. Deposition of fat in specific areas (hips, thighs) 7. Rapid increase in height and weight
Emotional and Psychological Changes (in both): 1. Mood swings and emotional sensitivity 2. Feeling of self-consciousness about body changes 3. Attraction towards the opposite sex 4. Desire for independence and identity formation 5. Changes in sleep patterns and appetite
Q2. Describe the major endocrine glands and the hormones they secrete. Answer:
| Endocrine Gland | Location | Hormones Secreted | Functions |
|---|---|---|---|
| Pituitary gland | Base of the brain | Growth hormone, TSH, ACTH, FSH, LH, Prolactin | Controls growth and regulates other endocrine glands (master gland) |
| Thyroid gland | Front of the neck, below the larynx | Thyroxine (T4), Triiodothyronine (T3) | Regulates metabolism of carbohydrates, fats, and proteins; requires iodine |
| Adrenal gland | On top of each kidney | Adrenaline (epinephrine), Cortisol | Adrenaline prepares body for fight-or-flight; cortisol regulates stress response |
| Pancreas | Behind the stomach | Insulin, Glucagon | Insulin lowers blood sugar; glucagon raises blood sugar |
| Testes (in males) | In the scrotum | Testosterone | Develops secondary sexual characteristics in boys; regulates sperm production |
| Ovaries (in females) | In the pelvic cavity | Estrogen, Progesterone | Develops secondary sexual characteristics in girls; regulates menstrual cycle |
Key points:
- Endocrine glands secrete hormones directly into the blood (not through ducts).
- Hormones are chemical messengers that travel through the bloodstream to target organs.
- Even tiny amounts of hormones can produce significant effects on the body.
- Over-secretion or under-secretion of hormones leads to disorders (e.g., dwarfism, goitre, diabetes).
Q3. Explain the menstrual cycle. Answer:
The menstrual cycle is a series of changes that occur in the female reproductive system approximately every 28 days. It has four main phases:
Q4. Discuss the role of nutrition and personal hygiene during adolescence. Answer:
Nutrition during Adolescence:
Adolescence is a period of rapid growth, so a balanced diet is essential:
1. Proteins — Required for building muscles and body tissues. Sources: pulses, eggs, meat, fish, milk, paneer. 2. Calcium — Essential for bone growth and strengthening. Sources: milk, curd, cheese, green leafy vegetables. 3. Iron — Needed for haemoglobin formation, especially important for girls due to menstrual blood loss. Sources: green leafy vegetables, jaggery, dates, meat, liver. 4. Iodine — Required for thyroxine production; deficiency causes goitre. Sources: iodized salt, seafood. 5. Vitamins and Minerals — Support overall growth and immunity. Sources: fresh fruits, vegetables, whole grains. 6. Carbohydrates and Fats — Provide energy for increased physical activity. Sources: rice, wheat, ghee, butter.
Dietary precautions:
- Avoid junk food and excessive sugar.
- Do not skip meals, especially breakfast.
- Drink plenty of water.
Personal Hygiene during Adolescence:
1. Bathing daily — Increased activity of sweat and sebaceous glands leads to body odour and acne. Regular bathing prevents infections. 2. Clean clothing — Wear clean, loose-fitting cotton clothes. Change undergarments daily. 3. Dental hygiene — Brush twice daily to prevent tooth decay and bad breath. 4. Menstrual hygiene (for girls):
5. Skin care — Wash face regularly to prevent acne. Avoid squeezing pimples. 6. Physical exercise — Regular exercise improves blood circulation, strengthens muscles, and reduces stress. 7. Adequate sleep — 8-10 hours of sleep is essential for growth and mental well-being.
- Use clean sanitary pads or cloths and change them regularly.
- Dispose of used pads properly.
- Wash the genital area with clean water.
- Avoid using scented products in the genital area.
Higher Order Thinking Questions
Q1. Why do adolescents experience mood swings? Answer: During adolescence, there is a surge in the production of sex hormones (testosterone in boys, estrogen in girls). These hormones affect the brain's neurotransmitter systems, leading to emotional changes. Additionally, the psychological stress of adjusting to physical changes, peer pressure, and identity formation contributes to mood swings.
Q2. Why is it important for adolescent girls to consume iron-rich foods? Answer: During menstruation, girls lose blood which contains haemoglobin (an iron-containing protein). Iron deficiency can lead to anaemia, causing fatigue, weakness, and reduced immunity. Therefore, girls need to consume iron-rich foods like green leafy vegetables, jaggery, dates, and meat to compensate for the monthly blood loss.
Q3. A couple has three daughters. What is the probability that their fourth child will be a son? Answer: The probability is 50% (or 1/2). Each fertilization is an independent event. The sex of each child is determined by whether an X or Y chromosome sperm fertilizes the egg. Since there is an equal chance of X or Y sperm fertilizing the egg, the probability remains 50% regardless of previous children's sex.
Common Mistakes
- Confusing adolescence with puberty: Adolescence is the entire period from childhood to adulthood (11-19 years). Puberty is a specific stage within adolescence when reproductive organs become functional.
- Saying sex of the baby is determined by the mother: The mother always contributes an X chromosome. The father's sperm carries either X or Y, so the father determines the sex.
- Calling menstruation a disease: Menstruation is a normal physiological process, not a disease or illness.
- Confusing growth hormone with thyroxine: Growth hormone (from pituitary) controls overall body growth; thyroxine (from thyroid) regulates metabolism. Deficiency of growth hormone causes dwarfism; deficiency of thyroxine causes goitre.
- Mixing up insulin and adrenaline functions: Insulin (from pancreas) lowers blood sugar; adrenaline (from adrenal gland) prepares the body for emergency action. They are not interchangeable.
- Confusing menarche with menopause: Menarche is the first menstrual cycle; menopause is the permanent end of menstruation.
- Saying adrenal gland is located near the brain: The adrenal glands are located on top of the kidneys, not near the brain. The pituitary gland is at the base of the brain.
Exam Checklist
- [ ] Can you define adolescence and puberty and distinguish between them?
- [ ] Can you list the secondary sexual characteristics in boys and girls?
- [ ] Can you name the major endocrine glands, their hormones, and functions?
- [ ] Can you explain why the pituitary gland is called the master gland?
- [ ] Can you describe the menstrual cycle and its four phases?
- [ ] Can you explain how the sex of a baby is determined (XX/XY chromosomes)?
- [ ] Can you discuss the importance of nutrition during adolescence (protein, calcium, iron, iodine)?
- [ ] Can you explain personal hygiene practices during adolescence, especially menstrual hygiene?
- [ ] Can you identify disorders caused by hormone deficiency (dwarfism, goitre, diabetes)?
- [ ] Can you explain the role of adrenaline as the emergency hormone?