NCERT Solutions Class 8 Science Chapter 10

NCERT Solutions for Class 8 Science Chapter 10

Science is a broad discipline that studies the structure and behaviour of the physical and natural world through observation and experimentation. Biology, chemistry, and physics are the three subjects of science education studied most often. Science is a human undertaking that spans the globe. The scientific process involves people from across the world. And you, unknowingly, are a part of it.

NCERT Class 8 Science Chapter 10 is about Reaching the Age of Adolescence. This chapter help students learn about adolescence, puberty changes, hormones in youth, sexual maturity in males and females, and menstrual cycles. Puberty, sexual characteristics, the roles of hormones in females, sex determination, and reproductive health care are covered in the chapter.

Extramarks NCERT solutions provide detailed and authentic answers to all the textbook questions. Through those, the students can understand, remember and retain answers to NCERT questions and thus, perform well in exams.

Class 8 Science Chapter 10 is built with many concepts, and to grasp each of those, students should go through the NCERT Solutions. As a result, Extramarks has developed Class 8 Science Chapter 10 Solutions. NCERT Solutions Class 8 Science Chapter 10 has been created exclusively by Extramarks experts.

Apart from NCERT Solutions for Class 8 Science Chapter 10, Extramarks is full of study material for all classes. In addition to these, students can use the Extramarks website to access several other study tools. For example, NCERT books, CBSE revision notes, CBSE sample papers, CBSE previous year question papers, and other materials are available to students.

Key Topics Covered in NCERT Solutions for Class 8 Science Chapter 10

To make it convenient for the students, Extramarks has listed below are key topics that are covered in NCERT Solutions for Class 8 Science Chapter 10:

Introduction to Adolescence and Puberty
Changes during Puberty
Talking about the Glands
Secondary sexual characteristics
Menstrual Cycle
Reproductive Phase in Human Lives
Sex Determination
Nutrition, Hygiene and Balanced Diet
Saying NO to Drugs

Let us look at Extramarks in-depth information on each subtopic in NCERT Solutions for Class 8 Science Chapter 10- Reaching the Age of Adolescence.

Introduction to Adolescence and Puberty

Extramarks NCERT Solutions for Class 8 Science Chapter 10 describes adolescence as the stage of life when the body experiences changes that lead to reproductive maturity. This is the period during which a youngster matures into an adult.

  • Adolescence starts at the age of 11 and lasts until 18 or 19.
  • Teenagers are another term for adolescents.
  • Puberty is defined by significant changes in the body that occur throughout this time.

Puberty is when the human body and reproductive systems undergo several changes that ultimately lead to sexual maturity.

  • The most notifiable change throughout puberty is that boys and girls become competent reproductively.
  • Puberty can start a year or two later in males than in girls.

Changes during Puberty

NCERT Solutions for Class 8 Science Chapter 10 by Extramarks explains the different changes everybody undergoes during puberty:

  • Increase in Height: When a child approaches puberty, their height starts increasing. Long bones develop quickly, resulting in a rise in height. By the age of 18, a person has reached their maximum height.
  • Change in Body Shape: Boys develop muscularity. Their shoulders expand, and their waist narrows. The girls’ waists broaden, and their shoulders shrink.
  • Change in Voice: The boys’ voices become thick and harsh. This occurs as the voice box grows in size. The females’ voices are generally high-pitched.
  • Increased activity of Sebaceous and Sweat Glands: Because perspiration and sebaceous gland secretions rise during this period, many teens get acne.
  • Development of Sex Organs: The testes and penis of boys grow, and sperm production begins. Girls’ ovaries develop and begin to release mature eggs.

Talking about the Glands

Extramarks NCERT Solutions for Class 8 Science Chapter 10 discusses the types of Glands and their functions in the human body.

Endocrine Gland

An endocrine system can be defined as a collection of ductless glands that secrete chemical molecules called hormones to regulate body processes and functions.

  • They immediately push their secretions into circulation.
  • Hormones frequently have a long distance between their source and the location of the action.

Hormones

Endocrine glands release hormones, which are chemical messengers. They oversee bodily functions, physiology, and behaviour.

Pituitary Gland

The master of all glands is the pituitary gland. This pea-sized structure is found at the base of the brain. Other glands in the body are controlled and regulated by them. For example, growth hormone, thyroid-stimulating hormone, LH, FSH, and other hormones are secreted by this gland.

  • The pituitary gland produces growth hormones, regulating a person’s general growth.
  • Growth hormone secretion is at its peak throughout adolescence.

Testosterone 

  • The predominant male sex hormone is testosterone.
  • This is also one of the key hormones responsible for the development of male secondary sexual traits as well as for the development of male reproductive organs and sperm production.
  • Only during puberty do the testes begin secreting testosterone.

Oestrogen

  • The predominant female sex hormone is estrogen/oestrogen.
  • Oestrogen oversees the development of female reproductive organs, creating female gametes (ova), secondary sexual traits, and the menstrual cycle.
  • After puberty, the ovaries release this hormone.

Thyroid Gland

  • In the neck, it is a butterfly-shaped gland.
  • It produces the hormone thyroxine.
  • This hormone is essential because it keeps all metabolic functions in control.
  • A lack of this hormone can cause thyroid gland enlargement, resulting in goitre.

Pancreas 

Insulin is a hormone produced by the pancreas that controls blood sugar levels. Diabetes is caused by insulin deficiency.

Adrenal Glands

  • The adrenal glands reside just above the kidneys.
  • They change form during a person’s life and shrink as they get older.
  • They emit the hormone adrenaline and regulate salt and pH levels.
  • Because it acts in emergency conditions, the hormone adrenaline is sometimes known as the “fight or flight” hormone.

Secondary sexual characteristics

NCERT Solutions for Class 8 Science Chapter 10 describes Sexual characteristics are physical or behavioural features identifying a living being’s biological sex. These are the characters:

  • Primary Sexual Characteristics: The sex organs utilised for reproduction with which a person is born are known as primary sexual characteristics. Testes in men and ovaries in females, for example.
  • Secondary Sexual Characteristics: Secondary sexual characteristics are traits that distinguish the sexes of a group of organisms that emerge throughout puberty.

The following are some of the sexual characteristics that males and females develop:

Boys grow beards, moustaches, and hair beneath their armpits, chests, and genital areas. They gain muscular mass and broaden their shoulders. They gain weight, and their voices become hushed.

In girls, the size of breasts grows. Their hips expand, and their vaginal region expands. Girls’ voices rise high-pitched throughout their menstrual cycle. They grow hair in their armpits and pubic areas as well.

Extramarks NCERT Solutions have defined secondary Sexual Characteristics for Class 8 Science Chapter 10 in the above passage. To get more details on it, refer to the Extramarks website.

Menstrual Cycle

NCERT Solutions for Class 8 Science Chapter 10 by Extramarks describes all aspects of the Menstrual cycle in females in the following:

  • Menstruation is a female-only reproductive cycle.
  • Menarche, also known as the start of the menstrual cycle, occurs during puberty.
  • Both the ovaries and the uterus go through cyclic alterations during the process.
  • An ovum grows and develops in the ovaries before being moved out.
  • A thick spongy inner lining extends inside the uterus in preparation for pregnancy.
  • Pregnancy happens when the egg is fertilised. If fertilisation does not occur, the free egg and the thicker uterine lining and blood vessels are lost if fertilisation does not occur.
  • In women, this results in menstruation or bleeding. Women’s menstrual cycles tend to end between 45 and 52.
  • Menopause is the stoppage of the menstrual cycle.
  • Between menarche and menopause, a woman’s reproductive age can be determined by her ability to have children.

Reproductive Phase in Human Lives

NCERT Solutions for Class 8 Science Chapter 10 highlights that the Adolescents’ testes and ovaries begin to create gametes after they enter puberty, therefore capable of reproduction.

When a girl hits puberty, usually between the ages of 10 and 12, she enters the reproductive period of her life. It lasts until a female is 45-50 years old.

The ova in a woman’s ovaries begin to develop at the start of adolescence, and one mature ovum is discharged once every 28-30 days. When an ovary releases an egg, this process is called ovulation. The uterine wall thickens currently to receive the fertilised egg. After fertilisation, the fertilised egg is implanted in the thick uterine wall, resulting in pregnancy.

For the cycles when fertilisation does not occur, the released egg and the uterine wall lining are released through the blood flow known as menstruation.

A woman’s reproductive life begins with menarche (her first menstrual flow) and concludes with menopause (when the menstrual cycle stops at 45-50 years of age).

Sex Determination

To comprehend how sex is determined, we must first understand the following procedure:

  • Humans have 23 chromosome pairs. Out of these 23 pairs, all 22 are Autosomes, and only one is what we refer to as the ‘Sex Chromosome,’ which is majorly involved in the sex determination process.
  • Both genders have two-sex chromosomal sets.
  • Males have one chromosome each of the X and Y chromosome (XY), both active.
  • Females have two X (XX) chromosomes, one of which is active.
  • Humans, mammals, insects, and a few plant species have the XY sex-determination mechanism.
  • Whether they are boys or girls, all children get one X chromosome from their mother. The kind of chromosome acquired from their father will decide the sex of the offspring.
  • A male will inherit the Y chromosome, whereas a girl will receive the X chromosome.

Balanced Diet, Hygiene and Physical Exercise

Balanced Diet

Adolescence is a period of rapid physical growth. As a result, all the nutrients are required by a developing person. As a result, all teens should eat a well-balanced diet rather than junk food.

A balanced diet contains the right amounts of proteins, carbs, fats, and vitamins. Junk food hurts a person’s development.

Personal Hygiene

Aside from consuming a healthy diet, it’s critical to keep our bodies and surroundings clean to avoid infections and illness. Adolescents must embrace personal hygiene practices such as bathing every day, washing hands before and after meals, avoiding defecating in the open, and girls keeping cleanliness during their menstrual cycle.

If teenage males and girls do not maintain personal hygiene, they risk contracting bacterial diseases.

Physical Exercise

Extramarks NCERT Solutions for Class 8 Science Chapter 10 highlights that Exercise can be the primary reason that keeps the body and mind in good shape. Physical activity can be of numerous forms, including walking, playing, and practicing yoga.

NCERT Solutions have briefly described the concept of a Balanced Diet, Hygiene, and Physical Exercises for Class 8 Science Chapter 10. To get more information about the same, refer to the Extramarks website. The website is home to numerous study materials.

Saying NO to Drugs

  • Drugs are addictive and cause long-term damage to the body.
  • Drugs can sometimes cause irreparable damage.
  • All youngsters should avoid drugs.
  • By sharing syringes used to inject drugs, HIV can be transmitted from an infected person to a healthy person.
  • It can also be passed on to a newborn through the mother’s milk if she is infected.
  • The virus could also be spread due to sexual contact with an HIV-positive individual.
  • People who are addicted to drugs have a higher risk of contracting HIV.

NCERT Solutions for Class 8 Science Chapter 10 Exercise and Solutions

Extramarks is a hub of quality study material. Students can use the study material prepared exclusively by Extramarks experts to excel in their examinations. Resources such as Past Year’s Question Paper, extra Notes, Question Answers, and many more are abundant. Click on the below links to view NCERT Solutions for Class 8 Science Chapter 10:

  • Class 8 Civics Chapter 10: Very Short Answer Type Questions
  • Class 8 Civics Chapter 10: Short Answer Type Questions
  • Class 8 Civics Chapter 10: Long Answer Type Questions

Students can access  NCERT Solutions for Class 8 Science Chapter 10 and other chapters by clicking here. In addition, students can also explore NCERT Solutions for other classes below.

By getting access to NCERT Solutions for Class 8 Chapter 10, students can easily understand all the concepts relating to adolescence.

NCERT Solutions Class 8 Science Chapter-wise List

Chapter 1 – Crop Production and Management
Chapter 2 – Microorganisms : Friend and Foe
Chapter 3 – Synthetic Fibres and Plastics
Chapter 4 – Materials : Metals and Non-Metals
Chapter 5 – Coal and Petroleum
Chapter 6 – Combustion and Flame
Chapter 7 – Conservation of Plants and Animals
Chapter 8 – Cell – Structure and Functions
Chapter 9 – Reproduction in Animals
Chapter 10 – Reaching The Age of Adolescence
Chapter 11 – Force and Pressure
Chapter 12 – Friction
Chapter 13 – Sound
Chapter 14 – Chemical Effects of Electric Current
Chapter 15 – Some Natural Phenomena
Chapter 16 – Light
Chapter 17 – Stars and The Solar System
Chapter 18 – Pollution of Air and Water

Key Features of NCERT Solutions for Class 8 Science Chapter 10

NCERT solutions provide detailed and authentic answers to all the textbook questions. Through those, the students can understand, remember and retain answers to NCERT questions and thus, perform well in exams

Extramarks NCERT Solutions are popular among students, as these help them achieve their goal of getting better grades. Based on the benefits, it is advised for students to go through the Extramarks NCERT Solutions for Class 8 Science Chapter 10 to obtain good results. Extramarks has done a commendable job by creating these NCERT Solutions. But why choose Extramarks? Here’s why:

  • Extramarks experts have exclusively created the NCERT Solutions after careful research and as per the needs of the students.
  • The language in these Solutions has been made is straightforward and easy to understand.
  • Based on the NCERT standards, Extramarks has compiled the most important material on this topic.

Q.1 What is the term used for chemical secretions of endocrine glands responsible for changes taking place in the body?

Ans-

The term used for secretions of endocrine glands responsible for changes taking place in the body is hormones. Hormones are the chemical substances that are directly released into blood steam by the endocrine glands.

Q.2 Define adolescence.

Ans-

Adolescence is the period in human life cycle that occurs after childhood and before adulthood, between the age 10 and 19. Adolescence is defined as the period of life when the body undergoes changes, leading to reproductive maturity.

Q.3 What is menstruation? Explain.

Ans-

Menstruation is the periodic discharge of thickened lining of uterus along with blood through vagina. It begins during puberty. Every month, female’s body releases an ovum and prepares itself for pregnancy by thickening the uterine walls. If pregnancy does not occur, then the thickened lining of uterus shed off along with the blood vessels. This discharge of blood is called menstruation.

Q.4 List changes in the body that take place at puberty.

Ans-

Certain changes that take place in the body of boys at puberty are:

  1. Sudden increase in height, during the age 13-14 years, that slows down around 18.
  2. Voice changes as the larynx begins to grow. The growing larynx can be seen as Adam’s apple.
  3. Change in body shape, like broadening of shoulders and muscular growth, also takes place.
  4. Organs, like testicles and penis, starts growing in size and attains their full size by the age of 17-18 years.
  5. Growth of pubic hair, facial hair, leg, chest and armpit hair starts in boys during puberty.
  6. Sweat glands and sebaceous glands become more active and result into pimples and acne.

Changes that take place in the body of girls at puberty are:

  1. Sudden increase in height, during the age of 11 years that slows down around 16.
  2. A drastic change in the shape of the body takes place due to the growth of breasts and widening of the region below the waist.
  3. Organs, like ovaries and uterus, start growing in size. Ovaries start releasing mature eggs.
  4. Pubic hair growth, as well as armpit and leg hair start growing in girls during puberty.
  5. Sweat glands and sebaceous glands become more active and result into pimples and acne.
  6. Onset of menstruation also takes place during puberty.

Q.5 Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.

Ans-

Endocrine Gland Hormone Secreted
Pituitary Growth hormone
Thyroid Thyroxine
Pancreas Insulin
Adrenal Adrenalin
Testes Testosterone
Ovaries Estrogen

Q.6 What are sex hormones? Why are they named so? State their function.

Ans-

The hormones that are produced by sex organs are termed as sex hormones. For example, testes release sex hormone called testosterone and ovary releases sex hormone called estrogen. They are named so because of their affect on the sexual behaviour of an organism.

Functions of sex hormones are:

  1. Testosterone: It is responsible for the development of secondary sexual characters in males, such as growth of facial hair and body hair, deepening of voice, broadening of shoulder, growth and development of reproductive organs, production of sperms, etc.
  2. Estrogen: It is responsible for the development of secondary sexual characters in females, such as breast enlargement, widening of region below waist, growth and development of reproductive organs, production of ova, etc.

Q.7 Choose the correct option.

(a) Adolescents should be careful about what they eat, because

(i) proper diet develops their brains.
(ii) proper diet is needed for the rapid growth taking place in their body.
(iii) adolescents feel hungry all the time.
(iv) taste-buds are well developed in teenagers.

(b) Reproductive age in women starts when their

(i) menstruation starts.
(ii) breasts start developing.
(iii) body weight increases.
(iv) height increases.

(c) The right meal for adolescents consists of

(i) chips, noodles, coke.
(ii) chapati, dal, vegetables.
(iii) rice noodles and burger.
(iv) vegetable cutlets, chips and lemon drink.

Ans-

(a) (ii) proper diet is needed for the rapid growth taking place in their body.

(b) (i) menstruation starts.

(c) (ii) chapati, dal, vegetables.

Q.8 Write notes on-

(a) Adam’s apple.

(b) Secondary sexual characters.

(c) Sex determination in the unborn baby.

Ans-

(a) Adam’s apple: In boys, during puberty, the voice box grows in size. This growing voice box can be seen as a protruding part of the throat called Adam’s apple. Due to this, boys have a deep voice.

(b) Secondary sexual characters: These are the features that help in distinguishing a male body from a female body. The secondary sexual characters appear at the time of puberty. Characters, like growth of hair in genitals and other body parts such as face, armpit, legs, chest etc., deepening of the voice, broadening of shoulder, and growth of muscles are male secondary sexual characters. On the other hand, characters, like growth of breasts, growth of hair in genitals and other body parts such as armpits, etc., widening of the region below waist are some of the female secondary sexual characters.

(c) Sex determination in the unborn baby: The sex of the unborn baby is determined by the type of male gamete that fuses with the female gamete. Human beings possess 23 pairs of chromosomes in the nucleus of their cells. Out of these 23 pairs, the last pair is known as the sex chromosome. The human males have 23 pairs of chromosomes including XY sex chromosomes. Therefore, the male gamete has 22 chromosomes and either an X or Y sex chromosome. Male gametes can be of two types: 22 + X and 22 + Y.

Females have 23 pairs of chromosomes including XX sex chromosomes. Therefore, their gametes can only have 22 chromosomes and one X chromosome i.e. 22 + X.

When a male gamete carrying X chromosome fuses with a female gamete, then a female child will be born after the gestation period. When a male gamete carrying Y chromosome fuses with a female gamete, then a male child will be born after the gestation period.

Q.9 Word game : Use the clues to work out the words.

Across

3. Protruding voice box in boys

4. Glands without ducts

7. Endocrine gland attached to brain

8. Secretion of endocrine glands

9. Pancreatic hormone

10. Female hormone

Down

1. Male hormone

2. Secretes thyroxine

3. Another term for teenage

5. Hormone reaches here through blood stream

6. Voice box

7. Term for changes at adolescence

Ans-

Q.10 The table below shows the data on likely heights of boys and girls as they grow in age. Draw graphs showing height and age for both boys and girls on the same graph paper. What conclusions can be drawn from these graphs?

Ans-

Following conclusions can be drawn from the graphs:

  1. At the time of birth, the height of girls and boys remain same.
  2. Up to the age of 8 years, the height of boys is more than that of the girls.
  3. After the age of 8 years, the height of girls outpaces the height of boys.
  4. After the age of 12 years, the height of boys speedily increases and reaches up to the height of girls at 16th year.
  5. After 16 years to 20 years, height of girls and boys increase but boys’ height is much more than that of the girls.

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FAQs (Frequently Asked Questions)

All the ideas in the chapter should be well understood by students. They should prioritise key exam topics before moving on to other issues. Students must thoroughly comprehend all ideas to respond to any question. It’s also a good idea to use diagrams wherever possible. To determine how well they have prepared for the exam, students should complete all the questions at the finish of Chapter 10 of Class 8 Science. They can also refer to NCERT Solutions for Class 8 Chapter 10 to understand better.

Age, reproductive health, stress, and mental health are all factors that influence sex hormones. Male and female sex hormones are the two types. Progesterone, oestrogen, and testosterone are female sex hormones. Male sex hormones, on the other hand, involve androgens, pituitary glands, and the hypothalamus.