"Reaching the Age of Adolescence" for Class 8 Science CBSE:-
Extra 20 important long questions and answers from the chapter:7
1. What is adolescence? Explain the physical changes that occur during this period.
Ans: Adolescence is the transitional period between childhood and adulthood, usually between 10-19 years. During this period, the body undergoes several physical changes:
Increase in height – Rapid growth in bones and muscles.
Change in body shape – Boys develop broader shoulders, and girls develop wider hips.
Development of reproductive organs – Testes and ovaries mature.
Growth of hair – Facial hair in boys, and underarm & pubic hair in both genders.
Voice change – Boys develop a deeper voice due to voice box enlargement.
Increased activity of sweat and oil glands – Leading to acne and pimples.
2. What is puberty? Mention the changes that occur in boys during puberty.
Ans: Puberty is the stage of life when an individual becomes capable of reproduction due to hormonal changes. In boys, puberty leads to:
Growth of facial and body hair (on the face, chest, armpits, and pubic region).
Deepening of voice due to the enlargement of the voice box (larynx).
Increase in height and muscle mass, making boys stronger.
Testes start producing sperm, making boys reproductively mature.
Oil and sweat glands become more active, leading to acne.
Emotional changes like mood swings and increased independence.
3. What changes occur in girls during puberty?
Ans: Girls undergo the following changes during puberty:
Breast development due to the release of estrogen.
Widening of hips to prepare for childbirth.
Menstruation (menarche) begins, signaling reproductive maturity.
Ovaries start releasing eggs (ovulation).
Growth of hair in the underarms and pubic region.
Increase in height and weight, with fat deposition in certain areas.
4. Explain the role of hormones in human growth and development.
Ans: Hormones are chemical messengers that control various body functions, including growth and puberty. Important hormones include:
Growth hormone (Pituitary gland) – Controls height and body growth.
Testosterone (Male hormone) – Develops male reproductive organs and secondary sexual characteristics.
Oestrogen (Female hormone) – Controls female reproductive development and menstrual cycle.
Thyroxine (Thyroid gland) – Regulates metabolism and energy production.
Adrenaline (Adrenal glands) – Helps the body respond to stress.
Insulin (Pancreas) – Regulates blood sugar levels.
5. What is the menstrual cycle? Describe its phases.
Ans: The menstrual cycle is a 28-day cycle in females where the body prepares for pregnancy. It has the following phases:
Menstrual phase (1-5 days) – The uterus lining sheds, causing bleeding (menstruation).
Follicular phase (6-13 days) – An egg matures in the ovary, and the uterine lining starts rebuilding.
Ovulation phase (14th day) – The ovary releases a mature egg.
Luteal phase (15-28 days) – If fertilization does not occur, the uterus prepares to shed its lining.
If fertilization occurs, the menstrual cycle stops, and pregnancy begins.
6. What is the importance of a balanced diet during adolescence?
Ans: A balanced diet is essential for growth and development in adolescents. It:
Provides energy for daily activities and body functions.
Helps in bone growth by supplying calcium and vitamin D.
Builds muscle mass with proteins.
Boosts immunity with vitamins and minerals.
Prevents deficiency diseases like anaemia (iron deficiency).
Supports brain function and concentration.
7. What is personal hygiene? Why is it important during adolescence?
Ans: Personal hygiene refers to keeping the body clean to prevent diseases. During adolescence, it is important because:
Sweat glands become more active, leading to body odour.
Oil glands produce more sebum, causing acne.
Regular bathing and washing hair prevent infections.
Wearing clean clothes helps prevent skin diseases.
Menstrual hygiene is crucial for preventing infections.
Brushing teeth regularly prevents cavities and bad breath.
8. Explain the importance of exercise during adolescence.
Ans: Exercise is crucial for adolescents because:
Helps in proper growth and muscle development.
Keeps bones strong and prevents diseases like osteoporosis.
Improves mental health by reducing stress and anxiety.
Boosts immunity by improving blood circulation.
Prevents obesity and lifestyle diseases.
Enhances overall fitness and energy levels.
9. What is the role of the pituitary gland in growth and puberty?
Ans: The pituitary gland is the master gland of the body and plays a major role in growth and puberty by:
Releasing growth hormone, which controls height.
Stimulating testes in boys to produce testosterone.
Stimulating ovaries in girls to produce oestrogen.
Regulating other endocrine glands.
Controlling metabolism and development.
Influencing reproductive functions.
10. What are the emotional and behavioural changes seen in adolescents?
Ans: Adolescents experience various emotional and behavioural changes, such as:
Mood swings due to hormonal changes.
Increased need for independence.
Curiosity and exploration about new things.
Stronger peer influence and friendships.
Developing self-identity and confidence.
Increased stress due to academic pressure.
11. What is meant by the term "sex determination" in humans?
Ans: Sex determination is the process by which a baby's gender is decided at the time of fertilization.
Humans have 46 chromosomes (23 pairs).
One pair (sex chromosomes) determines gender: XX for females, XY for males.
The mother always contributes an X chromosome.
The father can contribute either X or Y chromosome.
If the sperm carries X, the child is female (XX).
If the sperm carries Y, the child is male (XY).
12. What are endocrine glands? Name any three endocrine glands and their functions.
Ans: Endocrine glands are glands that release hormones directly into the blood. Three important endocrine glands are:
Pituitary gland – Controls growth, puberty, and other glands.
Thyroid gland – Produces thyroxine, which controls metabolism.
Adrenal glands – Produce adrenaline for emergency responses.
13. What is adolescence? Mention the important characteristics of this stage.
Ans: Adolescence is the period of transition between childhood and adulthood, usually between 10-19 years. The important characteristics of this stage are:
Rapid physical growth – Increase in height, weight, and muscle development.
Hormonal changes – Release of sex hormones like testosterone (in boys) and oestrogen (in girls).
Development of secondary sexual characteristics – Growth of body hair, voice changes, etc.
Emotional and psychological changes – Mood swings, self-awareness, and emotional instability.
Cognitive development – Improved reasoning and problem-solving skills.
Increased independence and self-identity formation.
14. What are the major differences between primary and secondary sexual characteristics?
Ans: The differences between primary and secondary sexual characteristics are:
|
Primary Sexual Characteristics |
Secondary Sexual Characteristics |
|---|---|
|
Present from birth |
Develop during puberty |
|
Related to reproductive organs |
Related to physical changes |
|
Examples: Testes in males, Ovaries in females |
Examples: Growth of body hair, voice change, breast development |
|
Directly responsible for reproduction |
Not directly involved in reproduction |
15. Explain the role of hormones in human reproduction.
Ans: Hormones play a crucial role in human reproduction by controlling puberty and reproductive functions.
Testosterone (Male hormone) – Controls sperm production, deepens voice, and promotes facial hair growth.
Oestrogen (Female hormone) – Responsible for the menstrual cycle, breast development, and egg maturation.
Progesterone – Supports pregnancy by maintaining the uterus lining.
Follicle-Stimulating Hormone (FSH) – Stimulates egg production in females and sperm production in males.
Luteinizing Hormone (LH) – Triggers ovulation in females and testosterone production in males.
Oxytocin – Helps in childbirth and milk ejection in mothers.
16. What is the importance of reproductive health during adolescence?
Ans: Reproductive health refers to maintaining hygiene, awareness, and care of reproductive organs. Its importance includes:
Prevention of infections and diseases – Maintaining hygiene prevents UTIs and reproductive infections.
Awareness about menstruation and puberty – Helps in managing physical and emotional changes.
Balanced diet and nutrition – Essential for proper growth and development.
Avoiding substance abuse – Smoking, alcohol, and drugs can harm reproductive health.
Understanding safe reproductive practices – Prevents early pregnancies and sexually transmitted diseases (STDs).
Encouraging open communication – Talking to parents and teachers about changes and concerns.
17. Explain why menstruation occurs and how it is related to reproduction.
Ans: Menstruation is the shedding of the uterine lining when fertilization does not occur. It is related to reproduction in the following ways:
Occurs due to hormonal changes – Estrogen and progesterone control the menstrual cycle.
Prepares the uterus for pregnancy – Every month, the uterus lining thickens for implantation of a fertilized egg.
Egg release (Ovulation) – If sperm fertilizes the egg, pregnancy occurs; otherwise, menstruation happens.
Cycles every 28 days – Menstruation usually repeats every 28-30 days.
Indicates reproductive health – A regular menstrual cycle is a sign of good reproductive health.
Stops during pregnancy – If fertilization occurs, menstruation ceases until childbirth.
18. Why is adolescence considered a critical stage for personal hygiene?
Ans: Adolescence is a critical stage for hygiene because of increased body changes and gland activities. Importance includes:
Increased sweating – Sweat glands become more active, leading to body odour.
Oil gland secretion – Causes pimples and acne on the face.
Menstrual hygiene in girls – Important to prevent infections.
Risk of fungal and bacterial infections – Due to improper hygiene habits.
Good hygiene builds confidence – Prevents embarrassment and promotes self-care.
Oral hygiene – Prevents cavities and bad breath.
19. How does gender influence growth patterns during adolescence?
Ans: Boys and girls grow at different rates and develop unique characteristics during adolescence:
Height increase – Boys generally experience a growth spurt later than girls.
Muscle vs. fat distribution – Boys develop more muscle mass, while girls gain fat in hips and thighs.
Voice changes – Boys' voices deepen, while girls’ voices remain relatively high-pitched.
Body hair growth – Boys develop facial and chest hair, while girls grow less visible body hair.
Menstruation in girls – Girls develop the menstrual cycle, whereas boys develop sperm production.
Hormonal variations – Testosterone in boys and oestrogen in girls cause different body changes.
20. What precautions should adolescents take to maintain good mental and physical health?
Ans: Adolescents should follow these precautions to ensure overall well-being:
Eat a balanced diet – Essential nutrients support body growth and brain development.
Maintain proper hygiene – Prevents infections and keeps the body healthy.
Engage in regular exercise – Helps in muscle and bone development.
Avoid stress and anxiety – Engage in hobbies and social interactions to reduce stress.
Avoid drugs and alcohol – Substance abuse can negatively affect physical and mental health.
Have open communication – Talking to parents, teachers, or counselors can help in managing emotions.
