Reaching the Age of Adolescence Class 8 Extra Questions Science Chapter 10

Reaching the Age of Adolescence Class 8 Extra Questions Very Short Answer Questions

Class 8 Science Chapter 10 Extra Questions Question 1.
What is Adam’s apple?
Answer:
The protruding part of the throat in males is called Adam’s apple.

Class 8 Science Ch 10 Extra Questions Question 2.
Name the hormone in female that is produced by ovaries and helps in development of mammary glands.
Answer:
Estrogen

Reaching The Age Of Adolescence Class 8 Extra Questions Question 3.
Whose height grow faster initially—boys or girls?
Answer:
Girls

Ncert Class 8 Science Chapter 10 Extra Questions Question 4.
Name a gland which transports secretions through ducts.
Answer:
Sweat glands/salivary glands/ oil gland (any one).

Reaching The Age Of Adolescence Class 8 Extra Questions Answers Question 5.
What is puberty?
Answer:
The age at which boys and girls become capable of reproduction.

Ch 10 Science Class 8 Extra Questions Question 6.
What are hormones?
Answer:
The chemical substances produced by endocrine glands are called hormones.

Chapter 10 Class 8 Science Extra Questions Question 7.
How long is a woman’s reproductive life lasts?
Answer:
Menarche to menopause.

Extra Questions For Class 8 Science Chapter 10 Question 8.
Name the female hormone.
Answer:
Estrogen

Reaching The Age Of Adolescence Extra Questions Question 9.
Which gland is called master gland?
Answer:
Pituitary gland

Questions On Reaching The Age Of Adolescence Question 10.
What is a balanced diet?
Answer:
The meal that includes all nutrients is called a balanced diet.

Reaching The Age Of Adolescence Class 8 Worksheets With Answers Question 11.
What is menstruation?
Answer:
Extrusion of uterus lining and blood along with the unfertilised egg from the vagina is called menstruation.

Chapter 10 Science Class 8 Extra Questions Question 12.
What is menarche?
Answer:
The first menstrual flow begins at puberty and is termed as menarche.

Class 8 Chapter 10 Science Extra Questions Question 13.
What is menopause?
Answer:
Stoppage of menstruation is called menopause.

Question 14.
What causes goitre?
Answer:
Deficiency of thyroxine hormone.

Question 15.
Which gland secretes thyroxine?
Answer:
Thyroid gland

Question 16.
What are chromosomes?
Answer:
The thread-like structures in the nucleus are called chromosomes.

Question 17.
How many chromosomes are present in human cell?
Answer:
23 pairs or 46 chromosomes.

Question 18.
How many sex chromosomes are there in human cell?
Answer:
Two, i.e., one pair.

Question 19.
Which hormone is necessary for normal growth of a person?
Answer:
Growth hormone.

Question 20.
Which gland secretes insulin?
Answer:
Pancreas

Question 21.
What causes diabetes?
Answer:
Deficiency of insulin.

Question 22.
Name the chromosome present in a female.
Answer:
X chromosome

Question 23.
Name the chromosome present in a male.
Answer:
X and Y chromosomes

Question 24.
Which chromosome does the unfertilised egg contain?
Answer:
X chromosome

Question 25.
Which hormone balances the proportion of salts in the blood?
Answer:
Adrenaline

Question 26.
What decides the sex of an unborn child?
Answer:
Sex chromosome of father.

Question 27.
Name the glands other than the pituitary gland.
Answer:
Thyroid, pancreas and adrenals.

Question 28.
When does the puberty ends?
Answer:
uberty ends when an adolescent reaches reproductive maturity.

Question 29.
Do the boys and girls undergo same physical changes at puberty?
Answer:
No

Question 30.
Why do we need to have a balanced diet?
Answer:
To keep the body healthy.

Reaching the Age of Adolescence Class 8 Extra Questions Short Answer Questions

Question 1.
What is meant by adolescence?
Answer:
Growing up is a natural process. The period of life, when the body undergoes several changes leading to reproductive maturity, is cabled adolescence. The adolescence period is 11 to 19 years of age.

Question 2.
What is puberty?
Answer:
The period during which adolescent boys and girls attain sexual maturity and become capable of reproduction is called puberty. Puberty age of female is 10 to 12 years while male puberty age is 12 to 14 years.

Question 3.
What is vital change which marks puberty in boys and girls?
Answer:
During puberty, the human body undergoes several changes, but the most important changes which marks puberty is that boys and girls become capable of reproduction.

Question 4.
Why do boys have a hoarse voice at puberty?
Answer:
The voice box or larynx begins to grow at the onset of puberty. This growing voice box in boys can be seen as a protruding part of the throat called Adam’s apple. This leads to voice becoming hoarse.

Question 5.
How does the body shape change at puberty?
Answer:
Body shape changes differently in boys and girls at puberty. Boys have broader shoulders and wider chests. Their muscles grow more prominently than girls. In girls, the region below the waist becomes wider.

Question 6.
Why is adolescence also called teenage?
Answer:
Adolescence period is generally 11 to 19 years of age. Because the period covers the teens, i.e., 13 to 19 years of age, adolescents are also called teenagers.

Question 7.
Why do many young people have acne and pimples during adolescence?
Answer:
During puberty the secretion of sweat glands and sebaceous glands (oil glands) increases. It develops acne and pimples on the face of young boys and girls.

Question 8.
Why are endocrine glands also called ductless glands?
Answer:
Endocrine glands release hormones directly into the blood stream. So, they are termed as ductless glands. For example, pituitary, thyroid, pancreas, etc.

Question 9.
What are secondary sexual characters?
Answer:
At puberty, in girls, breasts begin to develop, the region below the waist become wider, voice become shriller. Boys begin to grow facial hair, i.e., moustache and beard. Boys also develop hair on their chest, the muscles of the body grow more prominently, develop larger voice box which can be seen as a protruding part of the throat called Adam’s apple. In both boys and girls, hair grows under the arms and in the pubic region. As these features distinguish the male from the female they are called secondary sexual characters.

Question 10.
Explain the development of sex organs in male and female.
Answer:
The male and the female sex organs develop completely at puberty. Male sex organ like testes and penis develop completely. The testes begin to produce the male gametes or sperm. Similarly in girls the ovaries enlarge and egg begins to mature. Ovaries start releasing matured eggs or ovum.

Question 11.
Why do changes occur in human body at puberty?
Answer:
The changes in human body at puberty occur due to release of hormones by different types of glands. Hormones are chemical substances secreted from endocrine glands or endocrine system. Male hormone or testosterone are responsible for changes in male whereas female hormone or estrogen are responsible for changes in female.

Question 12.
What is a pituitary gland?
Answer:
Different types of hormones are secreted by different types of glands. The product of all these hormones is under the control of another hormone secreted from an endocrine gland called pituitary gland.

Question 13.
How do hormones work in human body?
Answer:
Endocrine glands release hormones into the blood stream to reach a particular body part called target site. The target responds to the hormone. There are many endocrine glands or ductless glands in the body.

Question 14.
What are sex hormones? How do they work in the human body?
Answer:
Sex hormones help boys and girls develop sex organs to enable them for reproduction. These hormones lead them to reproductive maturity.

In girls, estrogen makes the breasts develop. Milk secreting glands or mammary glands develop inside the breasts. Ovaries begin to produce eggs. In boys, testosterone is released by testes. Testes begin to release sperms. Changes in boys is also seen due to this hormone.

Question 15.
What is menstruation?
Answer:
At puberty, in girls the ovaries get enlarged and start producing eggs (ovum). One egg matures and is released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus becomes thick so as to receive the egg. If the egg is fertilised then it begins to develop and results in pregnancy. If this egg is not fertilised, the released egg and thickened lining of the uterus along with its blood vessels are shed off causing bleeding in female which is called menstruation. It occurs once in about 28 to 30 days.

Question 16.
What are the changes in female at the onset of puberty?
Answer:
There are several changes in females at the onset of puberty. They are:

growth of hair in armpit and pubic region.
development of breasts and mammary glands.
ovaries get enlarged and begin producing eggs.
menstruation cycle starts; and
increased activity of sweat and sebaceous glands.

Question 17.
Explain the terms menarche and menopause.
Answer:
The first menstrual flow begins at puberty and is termed as menarche.
At 45 to 50 years of age, the menstrual cycle stops. Stoppage of menstruation is called menopause.

Question 18.
What happens when the egg is fertilised?
Answer:
When the egg is fertilised, it begins to divide and then gets embedded in the uterus for further development. Finally the fertilised egg develops into a foetus.

Question 19.
What are the changes in males at puberty?
Answer:
There are various changes in males at puberty. They are:

sudden increase in height.
growth of hair at different parts of body like face, armpit and pubic region, development of moustache and beard.
development of Adam’s apple in throat, voice becomes hoarse.
shoulders become broader and chest wider.
growth of size of reproductive organs like penis, testes begin to produce sperms, etc.

Question 20.
What do you mean by reproductive health?
Answer:
The physical and mental well being of an individual is regarded as an individual’s health. To keep the body healthy, every human being, at any age, needs to have a balanced diet. The person must also observe personal hygiene and undertake adequate physical exercise.

Thus, reproductive health refers to the diseases, disorders and conditions that affect the functioning of the male and female reproductive system during all stages of life.

Question 21.
What is the role of hormones in completing the life history of insects and frogs?
Answer:
Hormones play an important role in the completion of life cycle of insects and frogs. Metamorphosis in insects is controlled by insect hormones. In a frog, it is controlled by thyroxine, the hormone produced by thyroid gland. Thyroxine production requires the presence of iodine in water. Water in which iodine is not, present, the tadpoles cannot become adult.

Question 22.
Which hormone is released by pancreas? What is its function?
Answer:
Insulin is released by pancreatic gland. It regulates sugar metabolism. If insulin is deficient in the body, sugar level becomes high in blood causing diabetes.

Reaching the Age of Adolescence Class 8 Extra Questions Long Answer Questions

Question 1.
What changes occur in human at puberty?
Answer:
There are various changes in human at puberty. They are as follows:

Change in height: During puberty, there is sudden increase in height in boys and girls. Initially, girls grow faster in height than in boys. But both reach their maximum height at the age of 18 years.
Change in voice: Boys develop larger voice box or larynx to form protruding part of throat called Adam’s apple making their voice hoarse, girls have high pitched voice.
Change in body shape: In boys, shoulders broaden and muscles grow more prominently than in girls. In girls the region below the waist becomes wider.
Secretion of sweat and sebaceous glands (oil glands) in both boys and girls increases and acne or pimples grow on faces of many youths.
Development of sex organs: In males, testes and penis develop completely. Testes begin producing sperms. In girls, ovaries are enlarged and begin to produce eggs. Both boys and girls reach reproductive maturity.
In girls, menstruation or periods starts.
All human beings attain mental, intellectual and emotional maturity at puberty.
Facial hair like moustache and beard are grown in boys. Hair are grown in armpit and pubic region in both boys and girls. Breasts are developed in girls. These characters are called secondary sexual characters as they distinguish a male from a female.

Question 2.
Explain the reproductive phase of life in humans.
Answer:
Boys and girls become capable of reproduction at puberty because their testes and ovaries begin to release gametes, i.e., sperms and ova respectively. In girls, reproductive phase of life begins at puberty from 10 to 12 years of age and generally lasts till the age of 45 to 50 years. The ova begin to mature with the onset of puberty. The ovum matures and is released by one of the ovaries once in 28 to 30 days.

During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilised and begins to develop. This results in pregnancy.
If fertilisation does not occur, the released egg, and the thickened lining of the uterus along with its blood vessels are shed off. This causes menstruation. It occurs once in about 28 to 30 days. The first menstrual flow begin at puberty and is termed as menarche. The menstruation stops at the age of 45 to 50. This stage is known as menopause.
In male, the reproductive phase begins at puberty at the ages 14-15 and lasts as long as he is healthy.

Question 3.
Mention different types of glands, their functions and hormones secreted by them.
Answer:
There are different types of glands in our body and they secrete different types of hormones which control groftoth, behaviour, development and reproduction. The following table shows different types of glands, hormones secreted by them and their functions:

Question 4.
Explain sex determination in human.
Answer:

Sex determination of a baby is done at the time of fertilisation when a male gametes fuse with a female gamete. It depends on male partner whether the baby will be a male child or female child. The chances of child to be male or female actually depend on the chromsomes present in the fertilised eggs or ova. There are 23 pairs of chromosomes in the nuclei of all human beings out of which two are sex chromosomes named X and Y. A male has one X and one Y chromosome and a female has two X chromosomes. The gametes (egg and sperm) have only one set of chromosomes. The unfetilised egg always has one X chromosome. But sperms are of two kinds. One kind has an X chromosome, and the other kind has a Y chromosome.

When a sperm containing X chromosome fertilises the egg, the zygote would have two X chromosomes and develop into a female child. If the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote would develop into a male child. Fig. 10.5 shows sex determination in humans.

Question 5.
Explain the term reproductive health. What should we do to maintain reproductive health?
Answer:
The state of physical, mental and social well being of an individual is regarded as an individual’s health. A healthy person is free from disease, tension and anxiety. Reproductive health refers to a state of physical, mental and social well-being in all matters relating to the reproductive system, at all stages of life. We should take following measures to maintain reproductive health:

To have a balanced diet: As far as practicable, we should have a balanced diet, i.e., a diet contain¬
ing proteins, vitamins, carbohydrates, fats and minerals. We can have our food which contain these nutrients.
To take physical exercise: We should take physical exercise like morning walk, running, etc., daily.
To maintain personal hygiene: We should maintain personal hygiene to stay fit and healthy. We should wash our body especially pubic region, armpit, etc., properly.
Avoid harmful drugs: We should avoid taking harmful drugs and alcohol.

Reaching the Age of Adolescence Class 8 Extra Questions Higher Order Thinking Skills

Question 1.
One day Seema’s uncle visited her place. Seema prepared dinner for him. When she was about to put rock salt on the salad, her uncle interrupted her and asked to put iodised salt instead of rock salt. He also advised her to prefer iodised salt instead of rock salt. Why do you think Seema’s uncle advised her to have iodised salt instead of rock salt?
Answer:
Deficiency of iodine causes goitre disease in our body. This is why Seema’s uncle advised her to have iodised salt.

Question 2.
It is said that height of a child depends upon the genes inherited from the parents. Are there factors other than genes that causes variation in height?
Answer:
Other factors like nutrition, release of growth hormones, exercises, diseases, etc., also have impact on the height of a growing child.

Question 3.
Is a woman responsible for the birth of a girl child? Explain.
Answer:
No, because a woman has eggs of only X chromosomes but a male has sperms of both X and Y chromosomes. It is the type of male chromosome (X or Y) which fuses with the egg and determine the sex of the foetus, i.e., whether it will be male (XY) or female (XX) child.

Question 4.
John and Radha were classmates since childhood. When Radha became eleven years old, she developed a little swelling on her neck. She visited the doctor who started medication for her. After a few years, John also developed a slight protrusion on his throat. He got worried and went to the doctor. But, the doctor assured him that it was a normal feature in boys while they are growing up. Can you think of any reasons for the difference in diagnoses?
Answer:
The swelling on the neck of Radha may be because of insufficient production of thyroxine which results in goitre. However slight protrusion in John’s throat may be due to enlargement of voice box, also known as Adam’s apple, in adolescent boys.

Question 5.
Why we should not take medicines or drugs unless prescribed by a doctor?
Answer:
Certain medicines have specific dosage levels and adverse side effects which if not followed may be proved lethal to us. Drugs can be addictive too and can ruin our health and happiness.

Reaching the Age of Adolescence Class 8 Extra Questions Value-Based Questions

Question 1.
Salma had a very soft and smooth skin during her childhood. As she entered adolescence, she developed pimples on her face, her body became taller compared to her face. She got worried of all of the sudden changes. Her mother explained that all these changes are normal and advised her to wash her face at regular intervals.

Why Salma’s mother advised Salma to wash her face at regular intervals?
What is the reason for appearance of pimples on her face?
Why Salma experienced disproportionate growth of the body?
What values do we get from this?

Answer:

Regular face wash keeps the face clean and dry and helps to reduce the pimples.
During adolescence, secretion of sweat glands and sebaceous glands increases leading to formation of acne and pimples.
During adolescence, all parts of the body do not grow at the same rate. Sometimes the arms and legs or hands and feet of adolescents look oversized and out of proportion with the body.
We must be self-aware, must take proper care and diet during the growing period, not get worried or lose our self-esteem.

Activities and Projects
Question 1.
Find out from your elder relatives about their awareness of the legal status of early marriage. You yourself may get information on it from your teacher, parents, a doctor or the internet. Write a two minute speech explaining why early marriage is not good for the couple.
Answer:
Our law does not permit the marriages of girls below 18 years of age and the boys below 21 years.
Biologically also, it is not good for both boys and girls. Early marriages are not good for the couple due , to following reasons:

Girls below the age of 18 are not biologically mature enough to produce a baby.
Boys also are not mature enough to take such a major responsibility to look after their child properly
and it creates many hurdles in the socio-economic development, education, maintaining livelihood, etc., of both the boys and girls. .
The newly born babies also have to suffer many problems regarding their proper care, etc.

Question 2.
Collect newspaper cuttings and information in magazines about HIV/AIDS. Write a one page article of 15 to 20 sentences on HIV/AIDS.
Answer:
Introduction: Acquired Immune Deficiency Syndrome (AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV). It may also be referred to as HIV disease or HIV infection. Following initial infection, a person may experience a brief period of influenza-like illqess. This is typically followed by a prolonged period without symptoms. As the infection progresses, it interferes more and more with the immune system, making the person much more susceptible to common infections, like tuberculosis, as well as opportunistic infections and tumors that do not usually affect people who have working immune systems. The late symptoms of the infection are referred to as AIDS. This stage is often complicated by an infection of the lung known as pneumocystis pneumonia, severe weight loss, skin lesions, or other AIDS-defining conditions.

Transmission: HIV is transmitted primarily via unprotected sex, contaminated blood transfusions,- hypodermic needles, and from mother to child during pregnancy, delivery, or breastfeeding. Some bodily fluids, such as saliva and tears, do not transmit HIV.

Prevention: Common methods of HIV/AIDS prevention include encouraging and practicing safe sex, needle-exchange programs, and treating those who are infected. There is no cure or vaccine; however, antiretroviral treatment can slow the course of the disease and may lead to a near-normal life expectancy.

Question 3.
In our country, according to 2011 census, there are 940 adolescent females for every 1000 males. Find out
(a) the concerns of the community regarding this low ratio. Remember that the chance of having a boy or a girl is equal.
(b) what amniocentesis is and how useful this technique is. Why is its use for identification of sex of the unborn child banned in India?
Answer:
(a) For a long, our society has been male dominated. There is also a belief that only the son can contin¬ue the lineage and the daughter is other’s property (paraya dhan). This belief leads to girl foeticide as in most cases, people want a son. This results in low sex ratio.
(b) Amniocentesis is a medical procedure used in prenatal diagnosis of chromosomal abnormalities, foetal infections and sex determination. For this a small amount of amniotic fluid, which contains foetal tissues, is sampled from the amniotic sac surrounding a developing foetus using a needle.
In India, selective abortion of female foetuses due to preference of male child has enforced Indian Government to ban sex-determination through amniocentesis.

Question 4.
Put your ideas together and write a short note on the importance of knowing facts about reproduction.
Answer:
Sex education or knowing facts about reproduction is very important due to the following reasons:

To know about the proper age of reproduction.
To become aware of safe sex, health and hygiene.
To maintain proper gap between two children because we come to know about different methods of family planning.
To be aware of myths, superstition, do’s or don’t.

I.Multiple Choice Questions (MCQs)
Choose the correct option.
Question 1.
The adolescence period is
(a) 14 – 20 years
(b) 10 – 18 years
(c) 11 – 19 years
(d) none of these

Question 2.
Larynx is called
(a) music box
(b) voice box
(c) respiratory organ
(d) sound box

Question 3.
Most adolescents attain their maximum height around the age of
(a) 22 – 25 years
(b) 13-15 years
(c) 11 – 12 years
(d) 18 – 19 years

Question 4.
Initially girls grow
(a) slower than boys
(b) faster than boys
(c) both of these
(d) none of these

Question 5.
Puberty age in females is
(a) 10 – 12 years
(b) 12 – 14 years
(c) 8-10 years
(d) 5-6 years

Question 6.
Puberty age in males is
(a) 12 – 14 years
(b) 13 – 15 years
(c) 10 – 12 years
(d) 18 -20 years

Question 7.
Thyroxine hormone is produced by
(a) adrenal gland
(b) testes
(c) pituitary gland
(d) thyroid gland

Question 8.
The male hormone is called
(a) estrogen
(b) testosterone
(c) thyroxine
(d) insulin

Question 9.
The female hormone is called
(a) estrogen
(b) testosterone
(c) adrenaline
(d) none of these

Question 10.
Menstruation occurs once in about
(a) 28 to 30 days
(b) 25 to 30 days
(c) 45 to 50 days
(d) none of these

Question 11.
The number of chromosomes present in human cell are
(a) 25 pairs
(b) 22 pairs
(c) 23 pairs
(d) none of these

Question 12.
The number of sex chromosomes are
(a) three
(b) two
(c) four
(d) none of these

Question 13.
The age of menopause stage is
(a) 45 to 50 years
(b) 40 to 45 years
(c) 50 to 55 years
(d) none of these

Question 14.
The unfertilised egg always has __________ chromosome
(a) X
(b) Y
(c) XY
(d) XX

Question 15.
A female has
(a) XY chromosomes
(b) YY chromosomes
(c) XX chromosomes
(d) none of these

Question 16.
The gametes have only
(a) one set of chromosomes
(b) two sets of chromosomes
(c) three sets of chromosomes
(d) none of these

Question 17.
Which of the following is male gonads?
(a) Moustache
(b) Chest
(c) Testes
(d) Hair

Question 18.
Production of thyroxine requires
(a) magnesium
(b) iodine
(c) sodium
(d) bromine

Question 19.
Which of the following determines the sex of the baby?
(a) Chromosomes
(b) Chloroplast
(c) Hormones
(d) Pituitary gland

Question 20.
Pancreas is responsible for maintaining
(a) blood pressure
(b) fat metabolism
(c) blood glucose level
(d) electrolyte balance
Answer:
1. (c)
2. (b)
3. (d)
4. (b)
5. (a)
6. (a)
7. (d)
8. (b)
9. (a)
10. (a)
11. (c)
12. (b)
13. (a)
14. (a)
15. (c)
16. (a)
17. (c)
18. (b)
19. (a)
20. (c)

II. Fill in the Blanks
Fill in the blanks with suitable word/s.
1. ___________ means to grow into maturity.
2. Children gain height during ___________.
3. The boys and girls passing through the adolescence period are called ___________ or ___________.
4. During puberty, a change in voice takes place due to the increase in the size of ___________ or ___________.
5. The stage when the menstrual cycle stops is called ___________.
6. The ___________ gland helps in controlling the production of both testosterone and estrogen hormones.
7. Diabetes is caused due to the deficiency of ___________ in the body.
8. ___________ is caused due to deficiency of thyroxine hormone.
9. Endocrine glands are also called ___________ glands.
10. ___________ secrets male sex hormones.
11. ___________ secrets female sex hormones.
12. Sex of the unborn child depends on whether the ___________ has ___________ or ___________ chromosomes.
13. Metamorphosis in insects is controlled by ___________ hormone.
14. Metamorphosis in frog is controlled by ___________ hormone.
15. If the water in which tadpoles are growing does not contain sufficient ___________, the tadpoles cannot become adults.
16. In females, the uterine wall thickens to receive the ___________.
17. Endocrine glands release hormones directly into the ___________ for transportation to the ___________.
18. ___________ helps the body to adjust and fight the stress.
19. The development of a caterpillar to an adult butterfly is termed as ___________.
20. The first menstrual flow begins at ___________ and is termed as ___________.
Answer:
1. Adolescence
2. puberty
3. adolescents, teenagers
4. voice box, larynx
5. menopause
6. pituitary
7. insulin
8. Goitre
9. ductless
10. Testes
11. Ovary
12. zygote, XX, XY
13. insect
14. thyroxine
15. iodine
16. zygote
17. blood stream, target site
18. Adrenaline
19. metamorphosis
20. puberty, menarche 18. Adrenaline

III. Match the following
Match the items given in column I suitably with those given in column II.

Answer:
1. (j)
2. (i)
3. (f)
4. (e)
5. (b)
6. (c)
7. (h)
8. (d)
9. (g)
10. (a)

IV, True or False
State whether the given statements are true or false.
1. The age of adolescence is 15 to 20 years.
2. The female puberty starts at the age of 12 to 14 years.
3. Boys have enlarged and well developed Adam’s apple.
4. Insulin is secreted by pituitary gland.
5. The chemical substances secreted by endocrine glands are called hormones.
6. . Estrogen is female hormone.
7. Testosterone is male hormone.
8. There are 23 pairs of chromosomes in the nuclei of human cell.
9. Menstruation stops in men permanently around the age of 45 to 50 years.
10. The estrogen hormone develops deeper voice in males at puberty.
11. The sex of an unborn child is determined after a foetus is formed.
12. Initially girls grow faster than boys.
13. Thyroxine hormone is released by thyroid gland.
14. Diabetes is caused due to the deficiency of adrenaline hormone.
15. Menstrual cycle in women is controlled by enzyme.
16. Growth hormones are secreted by pituitary glands.
17. Metamorphosis in insects are controlled by growth hormone.
18. Menstruation occurs once in about 28 to 30 days.
19. There are 3 sex chromosomes present in the nuclei of human being.
20. A male has two X chromosomes.
21. The gametes have only one set of chromosomes.
22. The unfertilised egg has two X chromosomes.
23. At puberty, the voice box or the larynx begins to grow.
24. When the zygote has one X and one Y chromosome, a male child is developed.
25. Menopause is the stage when menstruation starts.
Answer:
1. False
2. False
3. True
4. False
5. True
6. True
7. True
8. True
9. False
10. False
11. False
12. True
13. True
14. False
15. False
16. True
17. False
18. True
19. False
20. False
21. True
22. False
23. True
24. True
25. False

Reaching the Age of Adolescence Class 8 Extra Questions Science Chapter 10