CBSE Class 8 Science Chapter 10: Reaching the Age of Adolescence NCERT Solutions

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NCERT Solutions PDF Class 8 PDF

This chapter delves into the transformative period of adolescence, a crucial stage in human development. The NCERT Solutions for Class 8 Science, Chapter 10, 'Reaching the Age of Adolescence,' provide clear explanations of key concepts. Students will learn about the endocrine glands and the hormones they secrete, which regulate bodily changes. The solutions define adolescence and explain the physiological and psychological changes that occur during puberty, including the onset of menstruation in females and the development of secondary sexual characteristics in both sexes. Understanding these processes is vital for students as they navigate this significant phase of their lives. These solutions offer a detailed breakdown of the chapter's exercises, aiding students in grasping complex biological processes and preparing effectively for their exams.

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Quick info

BoardCBSE
ClassClass 8
SubjectScience
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 10: Reaching the Age of Adolescence

Chapter summary

Chapter 10, 'Reaching the Age of Adolescence,' focuses on the biological changes occurring during puberty. The NCERT Solutions cover the definition of adolescence, the role of hormones secreted by endocrine glands like the pituitary, thyroid, adrenal, pancreas, testes, and ovaries. It explains the process of menstruation and details the physical transformations experienced by both boys and girls, such as voice changes, increased height, and the development of secondary sexual characteristics. The solutions provide a structured approach to understanding these developmental milestones.

Learning outcomes

  • Understand the definition and duration of adolescence.
  • Identify the endocrine glands and the hormones they secrete.
  • Explain the process of menstruation and its biological basis.
  • Describe the physical changes that occur during puberty in boys and girls.
  • Recognize the role of hormones in bringing about changes during adolescence.

Topics covered

Paper topics

  • Adolescence
  • Puberty
  • Hormones
  • Endocrine Glands
  • Pituitary Gland
  • Thyroid Gland
  • Adrenal Gland
  • Pancreas
  • Testes
  • Ovaries
  • Menstruation
  • Secondary Sexual Characteristics

Important topics

  • Definition and onset of Adolescence
  • Role of Hormones and Endocrine Glands
  • Changes during Puberty (Boys and Girls)
  • Process of Menstruation
  • Secondary Sexual Characteristics

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Questions and Solutions

Question 1

What is the term used for secretions of endocrine glands responsible for changes taking place in the body?
Solution: The secretions of endocrine glands that are responsible for bringing about changes in the body are called hormones. Hormones act as chemical messengers, carrying signals from one cell or gland to another to regulate various bodily functions and developmental processes.

Question 2

Define adolescence.
Solution: Adolescence is the transitional stage of human life between childhood and adulthood, during which a person becomes capable of reproduction. This period is marked by significant physical, psychological, and emotional changes. In humans, adolescence typically begins around the age of 11 years and extends up to 18 or 19 years of age.

Question 3

What is menstruation? Explain.
Solution: Menstruation is a natural biological process that occurs in females. It begins around the onset of puberty, typically between the ages of 11 and 13. In the female reproductive system, the ovaries start maturing and releasing an egg (ovum) approximately once every 28 to 30 days. Simultaneously, the lining of the uterus thickens to prepare for the potential implantation of a fertilized egg. If fertilization does not occur, the released egg and the thickened uterine lining, along with its blood vessels, are shed and expelled from the body. This shedding results in bleeding, which is known as menstruation. The menstrual cycle repeats approximately every 28 to 30 days.

Question 4

List changes in the body that take place at puberty.
Solution: Puberty is a phase of rapid growth and development that leads to sexual maturity. Several significant changes occur in the body during this period for both boys and girls:

Common Changes in Boys and Girls:

  • Sudden Increase in Height: There is a rapid growth spurt, making individuals taller.
  • Change in Body Shape: Body proportions change as different parts grow at different rates.
  • Change in Voice: In boys, the voice box (larynx) enlarges, leading to a deeper and sometimes cracking voice. In girls, the voice becomes higher pitched.
  • Increased Activity of Sweat and Sebaceous Glands: These glands become more active, leading to increased sweating and sometimes acne.
  • Maturation of Reproductive Organs: The primary reproductive organs (testes in boys, ovaries in girls) mature and begin to function.
  • Appearance of Secondary Sexual Characteristics: These are features that distinguish males and females but are not directly involved in reproduction.

Specific Changes in Boys:

  • Facial hair, such as a beard and moustache, starts to grow.
  • Hair develops in the armpits, on the chest, and in the pubic region.
  • The voice becomes significantly deeper.
  • Muscles develop, and the shoulders become broader.
  • There is an overall increase in body weight.

Specific Changes in Girls:

  • Breasts begin to develop and enlarge.
  • Hair grows in the armpits and pubic regions.
  • The hips broaden, and the pelvic region widens.
  • The menstrual cycle begins (menarche).
  • Fat is deposited around the hips and thighs, contributing to a curvier body shape.

Question 5

Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.
Solution: Here is a table listing some major endocrine glands and the hormones they secrete:
Endocrine Gland Hormone Secreted
Pituitary Gland Growth Hormone
Thyroid Gland Thyroxine
Adrenal Gland Adrenalin
Pancreas Insulin
Testes (in males) Testosterone
Ovaries (in females) Oestrogen & Progesterone

Common mistakes

  • Confusing the terms puberty and adolescence.
  • Incomplete listing of endocrine glands and their hormones.
  • Not clearly explaining the cyclical nature of menstruation.
  • Failing to differentiate between changes in boys and girls during puberty.

Revision tips

  • Create flashcards for endocrine glands and their corresponding hormones.
  • Draw diagrams illustrating the changes during puberty for boys and girls.
  • Explain the concept of menstruation in your own words to a friend or family member.
  • Review the definitions of key terms like adolescence and puberty regularly.

Practice MCQs

Q1. What is the primary function of hormones secreted by endocrine glands?

Q2. Which period of life is characterized by the onset of reproductive maturity?

Q3. What is the term for the shedding of the uterine lining and blood if fertilization does not occur?

Q4. Which endocrine gland secretes insulin?

Q5. Which of the following is a secondary sexual characteristic typically observed in boys during puberty?

Frequently asked questions

What is adolescence according to NCERT Class 8 Science?

Adolescence is defined as the period of life when the body undergoes changes leading to reproductive maturity. It typically begins around the age of 11 and lasts until 18 or 19 years of age.

What are hormones and where are they secreted from?

Hormones are secretions of endocrine glands that are responsible for the changes taking place in the body. They act as chemical messengers.

What is menstruation?

Menstruation is the process where, if an egg is not fertilized, the thickened uterine lining along with blood vessels is shed, causing bleeding in females. This occurs approximately every 28 to 30 days.

List some common changes that occur during puberty.

Common changes include a sudden increase in height, voice changes, increased activity of sweat and sebaceous glands, maturation of reproductive organs, and the appearance of secondary sexual characteristics.

Which glands secrete hormones related to reproduction in males and females?

In males, the testes secrete testosterone. In females, the ovaries secrete oestrogen and progesterone.

How do these NCERT Solutions help students?

These solutions provide clear, step-by-step explanations for each exercise question, helping students understand complex concepts like puberty, hormones, and menstruation, and aiding in exam preparation.

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