Class 8 Science Chapter 7 Important Question Answers - Reaching the Age of Adolescence

Q1: What is the significance of the age of 10 or 11 in human growth and development, and why is it an important milestone for reproduction?
Ans: The age of 10 or 11 marks puberty, a period when significant physical and hormonal changes occur, leading to reproductive maturity. Before this age, the body is not ready for reproduction.

Q2: Define adolescence and explain when it typically begins and ends.
Ans: Adolescence is the period of life during which the body undergoes changes leading to reproductive maturity. It generally begins around the age of 11 and lasts until 18 or 19 years of age.
Q3: Why do some adolescents experience a sudden spurt in growth during puberty while others grow gradually?
Ans: Growth during puberty varies from person to person due to genetic factors and hormonal differences. Some may experience a sudden growth spurt, while others grow more gradually.

Q4: Explain how genes and nutrition influence an individual's height during adolescence.
Ans: Height is influenced by genetics inherited from parents, but proper nutrition during adolescence is essential for bones and muscles to receive adequate nourishment for growth.

Q5: Describe the changes in body shape that occur in adolescent boys and girls during puberty.
Ans: Boys experience broader shoulders and wider chests, while girls develop a wider region below the waist as part of their body shape changes during puberty.
Q6: What causes the voice change in adolescent boys, and what is the significance of Adam's apple in this context?
Ans: The voice change in boys is caused by the growth of the voice box or larynx. Adam's apple is a visible protrusion of the voice box during this change.

Q7: How does increased activity of sweat and sebaceous glands during puberty lead to issues like acne and pimples?
Ans: Increased gland activity can result in clogged pores and the development of acne and pimples on the skin.

Q8: Explain the development of sex organs in boys and girls during puberty.
Ans: In boys, the testes and penis develop, and the testes start producing sperm. In girls, the ovaries enlarge, and eggs begin to mature.

Q9: What changes in mental, intellectual, and emotional maturity occur during adolescence?
Ans: Adolescents become more independent and self-conscious and experience intellectual development. It is a time when the brain has the greatest capacity for learning.

Q10: Define secondary sexual characters and provide examples of such characteristics in both boys and girls.
Ans: Secondary sexual characteristics are physical traits that help distinguish males from females. Examples include facial hair in boys and breast development in girls.

Q11: How do hormones control the changes that occur during adolescence, and what role does the pituitary gland play in this process?
Ans: Hormones, such as testosterone and estrogen, control adolescent changes. The pituitary gland secretes hormones that stimulate the production of these sex hormones.

Q12: When do adolescents become capable of reproduction, and how does this capacity differ between males and females?
Ans: Adolescents become capable of reproduction when their testes and ovaries start producing gametes (sperm and eggs). Males have a longer reproductive phase than females.
Q13: Explain the menstrual cycle and its significance in females' reproductive health.
Ans: The menstrual cycle includes the maturation of eggs, their release, thickening of the uterine wall, and breakdown if pregnancy does not occur. It is essential for female reproductive health.

Q14: How is the sex of a baby determined, and why is it incorrect to blame the mother for the baby's sex?
Ans: The sex of a baby is determined by the combination of sex chromosomes from the father's sperm and the mother's egg. Blaming the mother for the baby's sex is unjustified, as the father's sex chromosomes play a crucial role.

Q15: What role do hormones play in completing the life history of insects and frogs during metamorphosis?
Ans: Hormones, such as thyroxine, control the metamorphosis of insects and frogs. In frogs, thyroxine production requires iodine in the water, and its absence can hinder metamorphosis.