ADOLESCENCE: A STAGE OF GROWTH AND CHANGE : Class 7 : Science
1. Meaning of Adolescence
Adolescence = the stage between childhood and adulthood.
It begins around 11–12 years and continues till 18–19 years.
During this period, boys and girls undergo physical, mental, emotional, and social changes.
2. Puberty
Puberty = the time when the body undergoes changes to become capable of reproduction.
In girls → puberty starts between 10–12 years.
In boys → starts between 12–14 years.
Visible changes occur in height, weight, body shape, and behavior.
3. Changes During Adolescence
a) Physical Changes
Rapid increase in height and weight.
Broadening of shoulders in boys; widening of hips in girls.
Growth of muscles, bones, and reproductive organs.
Development of secondary sexual characters (like facial hair in boys, breasts in girls).
b) Hormonal Changes
Controlled by endocrine glands (pituitary, thyroid, adrenal, testes, ovaries).
Pituitary gland secretes growth hormone and stimulates other glands.
Testes produce testosterone (boys), ovaries produce estrogen (girls).
c) Emotional & Mental Changes
Mood swings, attraction to opposite gender.
Increased ability to think, reason, and make decisions (cognitive growth).
4. Reproductive Maturity
Boys: production of sperm starts.
Girls: start of menstruation and production of eggs.
Marks the ability to reproduce.
5. Secondary Sexual Characters
Boys: facial and body hair, deep voice, broad shoulders.
Girls: growth of breasts, broader hips, menstruation, hair growth in underarms.
6. Nutritional Needs
Adolescents need a balanced diet with proteins, carbohydrates, fats, vitamins, and minerals.
Calcium & iron are very important for strong bones and healthy blood.
7. Personal Hygiene
More sweat and oil secretion → causes body odor and pimples.
Need for daily bathing, clean clothes, proper dental care, and hygiene during menstruation.
8. Role of Hormones
Hormones act as "chemical messengers".
Pituitary gland (master gland) controls secretion of testosterone (boys) & estrogen (girls).
9. Sex Determination
Father’s sperm decides the sex of the baby:
X chromosome (from sperm) + X chromosome (from egg) = Girl (XX).
Y chromosome (from sperm) + X chromosome (from egg) = Boy (XY).
10. Adolescents and Health
Avoid junk food, drugs, alcohol.
Follow exercise and sports for physical & mental growth.
Maintain proper sleep and stress-free lifestyle.
SHORT QUESTION ANSWERS
1. What is adolescence?
Adolescence is the period of life between childhood and adulthood, usually from 11 to 18 years.
2. What is puberty?
Puberty is the phase during which reproductive organs mature and secondary sexual characters appear.
3. At what age does puberty usually start in boys and girls?
Boys: 12–14 years, Girls: 10–12 years.
4. Name two secondary sexual characters in boys.
Growth of facial hair (mustache, beard), deepening of voice.
5. Name two secondary sexual characters in girls.
Development of breasts, broadening of hips.
6. Which gland is known as the master gland? Why?
Pituitary gland, because it controls other endocrine glands.
7. Name the hormone responsible for puberty in boys.
Testosterone.
8. Name the hormone responsible for puberty in girls.
Estrogen.
9. Which hormone controls growth in height?
Growth hormone secreted by the pituitary gland.
10. Why do adolescents have mood swings?
Due to hormonal changes and emotional development during puberty.
11. Why do adolescents need more calcium and iron?
Calcium helps in bone growth; iron is needed for blood and girls lose iron during menstruation.
12. What is menstruation?
The monthly discharge of blood and unfertilized egg in girls.
13. What is menarche?
The first menstrual cycle in a girl’s life.
14. What is menopause?
The natural stopping of menstrual cycle in women (around 45–50 years).
15. Which chromosome decides the sex of the child?
The father’s sperm (X = girl, Y = boy).
16. What changes occur in the voice of boys at puberty?
Voice becomes deep due to growth of voice box (larynx).
17. What changes occur in the voice of girls at puberty?
Girls’ voice becomes slightly shrill but not as deep as boys.
18. Why do pimples appear during adolescence?
Due to increased activity of sweat and oil glands.
19. Why should adolescents maintain personal hygiene?
To prevent body odor, skin infections, and diseases.
20. Give two examples of physical changes during puberty.
Increase in height, change in body shape.
21. Give two examples of emotional changes during adolescence.
Mood swings, attraction to opposite gender.
22. What are endocrine glands?
Glands that secrete hormones directly into the blood.
23. Name two endocrine glands other than pituitary.
Thyroid gland, adrenal gland.
24. Which hormone is produced by the thyroid gland?
Thyroxine.
25. Which hormone is produced by adrenal glands?
Adrenaline.
26. What is reproduction?
The process by which living organisms produce offspring.
27. Why is adolescence also called the stage of mental growth?
Because reasoning power, logical thinking, and decision-making develop.
28. What are chromosomes?
Thread-like structures in the cell nucleus that carry hereditary information.
29. How many chromosomes are present in human cells?
46 chromosomes (23 pairs).
30. Define secondary sexual characters.
Features that differentiate males and females but are not directly linked with reproduction.
31. Why should adolescents avoid junk food?
Junk food lacks nutrients and may cause obesity and poor growth.
32. Why should adolescents exercise regularly?
Exercise keeps body fit, improves blood circulation, and strengthens bones & muscles.
33. What is ovulation?
Release of an egg from the ovary in girls.
34. What is fertilization?
Fusion of male (sperm) and female (egg) gametes.
35. What is reproduction maturity?
The stage when organisms can reproduce sexually.
36. Which hormone is produced by testes?
Testosterone.
37. Which hormone is produced by ovaries?
Estrogen.
38. What are sex chromosomes?
X and Y chromosomes which determine the sex of an individual.
39. Why should adolescents get proper sleep?
Sleep helps in body growth and brain development.
40. List any two challenges faced during adolescence.
Emotional instability, peer pressure.
LONG QUESTION–ANSWERS
1. Define adolescence. Explain the age range and major changes seen in this stage.
Adolescence is the transitional stage between childhood and adulthood, usually from 11–18 years. In this stage, physical, emotional, mental, and social changes occur. Major changes include rapid growth in height and weight, development of reproductive organs, appearance of secondary sexual characters, mood swings, and increased reasoning ability.
2. What is puberty? Describe the main features of puberty.
Puberty is the period during which reproductive organs mature and the body becomes capable of reproduction. Main features include:
Growth spurt (increase in height and weight).
Development of secondary sexual characters.
Production of gametes (sperms in boys, eggs in girls).
Hormonal changes controlled by endocrine glands.
3. Write differences between adolescence and puberty.
Adolescence is the broad stage of growth (11–18 years) that includes physical, mental, and social changes. Puberty is a short phase within adolescence during which reproductive organs mature and physical changes occur. Adolescence is wider, while puberty is specific to sexual maturity.
4. List and explain five physical changes during adolescence.
Increase in height and weight.
Change in body shape (shoulders broaden in boys, hips widen in girls).
Growth of reproductive organs.
Development of secondary sexual characters.
Increased secretion of sweat and oil glands.
5. List and explain five emotional changes during adolescence.
Mood swings due to hormonal changes.
Attraction towards opposite sex.
Need for independence.
Development of self-identity.
Increased curiosity and questioning attitude.
6. What are secondary sexual characters? Give examples in boys and girls.
Secondary sexual characters are features that differentiate males and females but are not directly related to reproduction.
Boys: facial hair, deep voice, broad shoulders.
Girls: development of breasts, wider hips, start of menstruation.
7. Describe the role of hormones during adolescence.
Hormones act as chemical messengers. Pituitary gland secretes growth hormone and controls other glands. Testes secrete testosterone (responsible for male puberty), ovaries secrete estrogen (responsible for female puberty). Thyroid and adrenal glands also help in growth and metabolism.
8. Explain the role of the pituitary gland.
The pituitary gland is called the master gland because it controls all other endocrine glands. It secretes growth hormone (for height and body growth) and stimulates testes and ovaries to produce testosterone and estrogen.
9. What changes occur in boys during puberty?
Broadening of shoulders.
Growth of facial and chest hair.
Deepening of voice due to enlarged larynx.
Development of reproductive organs and production of sperms.
Rapid increase in height and muscle growth.
10. What changes occur in girls during puberty?
Development of breasts.
Broadening of hips.
Start of menstruation.
Development of reproductive organs and production of eggs.
Slight change in voice.
11. Describe the menstrual cycle.
Menstrual cycle is the monthly discharge of blood and unfertilized egg in females. It begins at menarche and continues till menopause. It usually lasts 28 days. If fertilization does not occur, the thickened lining of uterus breaks down and flows out as blood.
12. What is menarche and menopause?
Menarche is the first menstrual cycle in girls (10–14 years). Menopause is the natural stopping of menstruation around 45–50 years of age.
13. Explain the process of sex determination in humans.
Human cells have 23 pairs of chromosomes. Out of these, 22 pairs are normal and 1 pair are sex chromosomes. The mother contributes an X chromosome. The father contributes either an X (girl) or Y (boy) chromosome. Hence, the father’s sperm decides the sex of the child.
14. Why do adolescents need a balanced diet?
Adolescents need extra energy and nutrients for growth. Proteins help in body building, carbohydrates and fats provide energy, calcium strengthens bones, iron builds blood, vitamins and minerals help immunity. Junk food should be avoided.
15. What hygiene measures should adolescents follow?
Adolescents should bathe daily, wear clean clothes, wash hands before and after meals, brush teeth regularly, keep nails trimmed, and maintain menstrual hygiene. This prevents infections, skin problems, and bad odor.
16. Why do adolescents suffer from acne and pimples? How can they prevent it?
During puberty, oil and sweat glands become overactive, causing acne and pimples. Preventive measures: wash face regularly, maintain hygiene, avoid oily food, drink plenty of water.
17. Why should adolescents exercise regularly?
Exercise strengthens muscles and bones, improves blood circulation, controls body weight, reduces stress, and helps in proper growth and brain development.
18. Why is sleep important for adolescents?
Sleep gives rest to body and brain, helps in growth hormone secretion, improves concentration, memory, and learning. Lack of sleep causes stress and poor performance.
19. What is reproductive maturity? Explain in boys and girls.
Reproductive maturity is the stage when an individual can reproduce. Boys achieve it when they start producing sperms (13–16 years). Girls achieve it when ovulation and menstruation begin (10–14 years).
20. Explain the difference between primary and secondary sexual characters.
Primary sexual characters are directly related to reproduction (testes in boys, ovaries in girls). Secondary sexual characters are external features like beard, breasts, body shape, and voice changes.
21. What is fertilization? Explain internal fertilization in humans.
Fertilization is the fusion of male and female gametes. In humans, it occurs inside the female’s body (internal fertilization) when sperm fuses with egg in the fallopian tube to form a zygote.
22. Why is adolescence also called a stage of mental development?
Because during adolescence, reasoning power, logical thinking, decision-making, problem solving, and social awareness improve.
23. Why should adolescents avoid drugs and alcohol?
Drugs and alcohol damage brain and liver, cause addiction, reduce concentration, spoil studies and future, and may lead to social problems.
24. How do boys and girls differ in growth spurt during adolescence?
Girls usually grow faster than boys at the beginning of adolescence. Boys catch up later and often become taller and stronger.
25. Explain the role of testosterone.
Testosterone is the male sex hormone secreted by testes. It controls development of secondary sexual characters like beard, mustache, deep voice, broad shoulders, and sperm production.
26. Explain the role of estrogen.
Estrogen is the female sex hormone secreted by ovaries. It controls development of secondary sexual characters like breasts, menstruation, and ovulation.
27. What is the role of the thyroid gland?
Thyroid gland produces thyroxine which controls body metabolism, growth, and development.
28. What is the role of the adrenal gland?
Adrenal gland produces adrenaline (“fight or flight hormone”), helps body cope with stress, increases heartbeat, and prepares body for emergencies.
29. Explain why adolescence is a stage of social change.
Adolescents form new friendships, develop social awareness, start caring about others’ opinions, feel peer pressure, and learn responsibility as future adults.
30. How should society support adolescents?
By providing guidance, counseling, emotional support, balanced diet, proper education, and safe environment to grow into healthy adults.
31. Why is adolescence called the stage of growth spurt?
Because during this stage, bones and muscles grow rapidly, height increases suddenly, and weight also increases.
32. What is the importance of education during adolescence?
Education helps adolescents understand changes, avoid myths, develop career goals, and make informed decisions about health and future.
33. Describe briefly the reproductive system in boys and girls.
Boys: Testes produce sperms, penis helps transfer sperms.
Girls: Ovaries produce eggs, uterus provides place for fetus development, vagina receives sperms.
34. What is peer pressure? How can adolescents deal with it?
Peer pressure is the influence of friends to behave in a certain way. Adolescents should stay confident, avoid bad habits, and choose positive company.
35. Summarize the main challenges faced by adolescents.
Physical changes, emotional instability, mood swings, peer pressure, lack of guidance, addiction risks, and nutritional needs. With proper support and education, these can be overcome.
MCQS
1. The period between childhood and adulthood is called:
a) Infancy
b) Adolescence
c) Puberty
d) Maturity
✅ Answer: b) Adolescence
2. The stage when the body becomes capable of reproduction is called:
a) Fertilization
b) Puberty
c) Menarche
d) Menopause
✅ Answer: b) Puberty
3. Puberty begins in girls around the age of:
a) 8 years
b) 10–12 years
c) 14–16 years
d) 18 years
✅ Answer: b) 10–12 years
4. Puberty begins in boys around the age of:
a) 10 years
b) 11 years
c) 12–14 years
d) 16 years
✅ Answer: c) 12–14 years
5. Which gland is called the “master gland”?
a) Thyroid
b) Adrenal
c) Pituitary
d) Pancreas
✅ Answer: c) Pituitary
6. The hormone secreted by testes is:
a) Estrogen
b) Progesterone
c) Testosterone
d) Insulin
✅ Answer: c) Testosterone
7. The hormone secreted by ovaries is:
a) Testosterone
b) Estrogen
c) Thyroxine
d) Adrenaline
✅ Answer: b) Estrogen
8. The female reproductive cell is:
a) Sperm
b) Egg (ovum)
c) Zygote
d) Embryo
✅ Answer: b) Egg (ovum)
9. The male reproductive cell is:
a) Egg
b) Zygote
c) Sperm
d) Ovary
✅ Answer: c) Sperm
10. Fertilization in humans is:
a) External
b) Internal
c) Both
d) None
✅ Answer: b) Internal
11. The chromosome pair in a girl is:
a) XY
b) XX
c) YY
d) None
✅ Answer: b) XX
12. The chromosome pair in a boy is:
a) XX
b) XY
c) YY
d) XYX
✅ Answer: b) XY
13. Which parent determines the sex of the child?
a) Mother
b) Father
c) Both
d) Neither
✅ Answer: b) Father
14. The age at which menstruation starts is called:
a) Menopause
b) Menarche
c) Ovulation
d) Puberty
✅ Answer: b) Menarche
15. Stoppage of menstruation occurs at:
a) Menarche
b) Menopause
c) Puberty
d) Adolescence
✅ Answer: b) Menopause
16. The voice of boys deepens due to enlargement of:
a) Nose
b) Larynx
c) Tongue
d) Brain
✅ Answer: b) Larynx
17. Which of these is a secondary sexual character in boys?
a) Production of sperm
b) Growth of beard and mustache
c) Presence of testes
d) Broadening of hips
✅ Answer: b) Growth of beard and mustache
18. Which of these is a secondary sexual character in girls?
a) Production of eggs
b) Development of breasts
c) Presence of ovaries
d) Formation of uterus
✅ Answer: b) Development of breasts
19. The hormone responsible for male puberty is:
a) Estrogen
b) Testosterone
c) Progesterone
d) Thyroxine
✅ Answer: b) Testosterone
20. The hormone responsible for female puberty is:
a) Estrogen
b) Testosterone
c) Insulin
d) Adrenaline
✅ Answer: a) Estrogen
21. Growth spurt during adolescence is due to:
a) Estrogen
b) Testosterone
c) Growth hormone
d) Thyroxine
✅ Answer: c) Growth hormone
22. The thyroid gland produces:
a) Adrenaline
b) Insulin
c) Thyroxine
d) Testosterone
✅ Answer: c) Thyroxine
23. The adrenal gland produces:
a) Thyroxine
b) Adrenaline
c) Estrogen
d) Testosterone
✅ Answer: b) Adrenaline
24. Which of the following is NOT a part of personal hygiene?
a) Regular bathing
b) Eating junk food
c) Brushing teeth
d) Washing hands
✅ Answer: b) Eating junk food
25. Acne and pimples in adolescents are caused by overactivity of:
a) Salivary glands
b) Oil and sweat glands
c) Pituitary gland
d) Thyroid gland
✅ Answer: b) Oil and sweat glands
26. Which of the following nutrients is important for blood?
a) Calcium
b) Iron
c) Protein
d) Carbohydrate
✅ Answer: b) Iron
27. Which nutrient helps in growth and body building?
a) Protein
b) Carbohydrate
c) Fat
d) Vitamin
✅ Answer: a) Protein
28. The zygote is formed by:
a) Egg + Egg
b) Sperm + Sperm
c) Sperm + Egg
d) Egg + Chromosome
✅ Answer: c) Sperm + Egg
29. How many pairs of chromosomes are present in human cells?
a) 22
b) 23
c) 44
d) 46
✅ Answer: b) 23
30. The master control of puberty lies in:
a) Liver
b) Pituitary gland
c) Heart
d) Kidney
✅ Answer: b) Pituitary gland
31. Which of the following is an example of emotional change during adolescence?
a) Growth of hair
b) Mood swings
c) Development of breasts
d) Broadening of shoulders
✅ Answer: b) Mood swings
32. The stage when adolescents become capable of reproduction is called:
a) Childhood
b) Adulthood
c) Reproductive maturity
d) Infancy
✅ Answer: c) Reproductive maturity
33. The duration of menstrual cycle is approximately:
a) 7 days
b) 15 days
c) 28 days
d) 40 days
✅ Answer: c) 28 days
34. The union of sperm and egg forms a:
a) Embryo
b) Zygote
c) Fetus
d) Baby
✅ Answer: b) Zygote
35. The organ where the fetus develops is:
a) Ovary
b) Fallopian tube
c) Uterus
d) Vagina
✅ Answer: c) Uterus
36. Which is NOT advised for adolescents?
a) Exercise
b) Adequate sleep
c) Junk food
d) Balanced diet
✅ Answer: c) Junk food
37. Peer pressure means:
a) Support from teachers
b) Influence of friends
c) Love from parents
d) Guidance from elders
✅ Answer: b) Influence of friends
38. Which factor decides the sex of a child?
a) Mother’s egg
b) Father’s sperm
c) Both
d) Uterus
✅ Answer: b) Father’s sperm
39. The sudden increase in height during adolescence is called:
a) Growth spurt
b) Fertilization
c) Menarche
d) Hormonal change
✅ Answer: a) Growth spurt
40. Adolescents should avoid drugs and alcohol because:
a) They increase energy
b) They are healthy
c) They damage brain and body
d) They improve studies
✅ Answer: c) They damage brain and body
