10. Reaching the age of adolescence Science class 8 exercise Additional Questions With Solutions
10. Reaching the age of adolescence Science class 8 exercise Additional Questions With Solutions ncert book solution in english-medium
NCERT Books Subjects for class 8th Hindi Medium
Chapter Review
Chapter Review:
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Growing up is a natural process. The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence.
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The human body undergoes several changes during adolescence. These changes mark the onset of puberty.
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The period covers the ‘teens’ (13 to 18 or 19 years of age), adolescents are also called ‘teenagers’.
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Height depends on the genes inherited from parents.
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During puberty the secretion of sweat glands and sebaceous glands (oil glands) increases.
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Endocrine glands release hormones directly into the bloodstream. So, they are also termed ductless glands.
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In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, moustaches and beard.
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The changes which occur at adolescence are controlled by
hormones. -
The male hormone is testosterone and the female
hormone is estrogen. -
Development of sexual organ as well as they produce sperm and ovum. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, moustaches and beard. Hair grows under the arms and in the region above the thighs or the pubic region.
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The ovary releases eggs for fertilization. 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 bleeding in women which is called menstruation.
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Testes and ovary are even exocrine glands, which secrete sex hormone. These are responsible for secondary sexual characters so these are called sex hormones. The sex hormones are under the control of hormones from pituitary gland.
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The chromosomes which determine the sex in the human beings are called sex- chromosomes. These are two ane is ‘X’ and another ‘Y’. A female has two X chromosomes, while a male has one X and one Y chromosome.
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First The first menstrual flow begins at puberty and is termed menarch .
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At 45 to 50 years of age, the menstrual cycle stops. Stoppage of menstruation is termed menopause.
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The reproduction period in lady Starts in age of 10 – 12th years and ends in age of 40 – 45th .
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Endocrine glands release hormones into the bloodstream to reach a
particular body part called target site. -
The growing voice box in boys can be seen as a protruding part of the throat called Adam’s apple.
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Pituitary also secretes growth hormone which is necessary for the normal growth of a person.
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All human beings have 23 pairs of chromosomes in the nuclei of their cells.
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A female has two X chromosomes, while a male has one X and one Y chromosome.
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This change from larva to adult is called metamorphosis.
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Metamorphosis in insects is controlled by insect hormones. In a frog, it is controlled by thyroxine, the hormone produced by thyroid.
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A balanced diet means that the meals includs proteins,carbohydrates,fats and vitamins in requisite proportions.
Text Book Exercise
Exercise
1. What is the term used for secretions of endocrine glands responsible for changes taking place in the body?
Answer : The term used for secretions of endocrine glands is hormoane which is responsible for various changes taking place in the body.
2. Define adolescence.
Answer : The period of life when the body undergors changes, leading to reproductive maturity, is called adolescence.
3. What is menstruation? Explain.
Answer : When the uterus receives the egg and it is fertilized, pregnacy occurs. If fertilization does not occur, the released egg and the thickened lining of the uterus along with its blood vesssels are shed off. This causes bleeding in women which is called menstruation.
4. List changes in the body that take place at puberty.
Answer : The onset of puberty brings about :
(i) Growth of the reproductive organs which begin to function. (ii) Hair grows at various places of the body. Breasts develop in girl and facial hair (moustache and beard) apper in boys.
(iii) Voice of the boys becomes hoarse as voice box enlarges during adolescence.
5. Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.
Answer:
Name of endocrine glands | Hormones secreted |
testes | Testosterone |
Ovary | Estrigen |
Adrenal | Adrenalin |
Thyroid glands | Thyroxine |
Pituitary | FSH or Fillicle atimulating hormonre |
Pancreas | Insulin |
6. What are sex hormones? Why are they named so? State their function.
Answer:
Hormones secreted by testes and ovaries are termed as sex-hormones.
They are named so because they are secreted by the reproductive organs.
Function of sex-hormones:
They hormones are responsible for the secondary sexual charaters of male and female.
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.
Answer:
(a) (ii), (b) (i), (c) (ii).
8. Write notes on—
(a) Adam’s apple.
(b) Secondary sexual characters.
(c) Sex determination in the unborn baby.
Answer:
(a) Adam's apple: In human males, the larynx grows larger during puberty and can be seen as a protruding part of the throat. This protrusion is known as the Adam's apple. In boys, under the influence of sex hormones, the larynx becomes prominent, As a result, the vocal cords become longer and thicker, causing the voice to become hoarse.
Concept insight: At puberty, boys develop a larger voice box called Adam's apple.
(b) Secondary sexual characters are those features that help in distinguishing the male and the female body from each other. They are physical or behavioral characteristics that appear in humans at the time of puberty.
Secondary sexual characters in boys:
(i) Appearance of moustache and beard.
(ii) Appearance of chest hair.
(iii) Growth of hair in genital area and other parts of the skin.
Secondary sexual characters in girls:
(i) Increase in breast size and darkening of the skin of nipples present at the tip of the breasts.
(ii) Growth of hair in genital area and other body parts.
Concept insight: Secondary sexual characters are developed during puberty.
(c) Sex determination in an unbom baby:
The sex of a baby is determined by the type of male gamete that fuses with the female gamete.
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 hormons
10. female hormone
Down
1. Male hormone
2. Secretes thyroxine
3. Another therm for teenage
5. Hormone reaches here through blood stream
6. Voice box
7. Term for changes at adolescence
Answer:
Text Book Exercise
Addtional - Question
Additional Questions With Solutions
Ques: What is adolescence?
Ans: Growing up is a natural process. The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence.
Ques: What is the most important change of puberty?
Ans: Boys and girls become capable of reproduction.
Ques: What is the most conspicuous change during puberty?
Ans: The most conspicuous change during puberty is the sudden increase in height.
Ques: Why are endocrine glands called ductless glands?
Ans: Endocrine glands release their hormone directly through the bloodstream not through any duct (pipe), hence these are called ductless glands.
Ques: Why do many people get more acne and pimples on the face during puberty?
Ans: During puberty the secretion of sweat glands and sebaceous glands (oil glands) increases. Many young people get acne and pimples on the face at this time because of the increased activity of these glands in the skin.
Ques: List changes in the body that take place at puberty.
Ans:
(i) Increase in height.
(ii) Change in the body shape – In Boys, shoulders generally broaden as a result of growth. In girls, the region below the waist becomes wider.
(iii) Heaviness in voice.
(iv) Increased Activity of Sweat and Sebaceous Glands.
(v) Development of sex organ – male sex organs like the testes and penis develop completely. In girls, the ovaries enlarge and eggs begin to mature. Also ovaries start releasing mature eggs.
(vi) Reaching Mental, Intellectual and Emotional Maturity.
(vii) Secondary sexual characters – Development of sexual organ as well as they produce sperm and ovum. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, moustaches and beard. Hair grows under the arms and in the region above the thighs or the pubic region.
Ques: What is Secondary sexual characters?
Ans: Development of sexual organ as well as they produce sperm and ovum. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, moustaches and beard. Hair grows under the arms and in the region above the thighs or the pubic region.
Ques: Name the substances which are responsible for physical changes in the body secreted by exocrine glands.
Ans: Hormone.
Ques: What is menstruation?
Ans: The ovary releases eggs for fertilization. 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 bleeding in women which is called menstruation.
Ques: What are the sex hormones? Why are they named so? State their function.
Ans: Testes and ovary are even exocrine glands, which secrete sex hormone. These are responsible for secondary sexual characters so these are called sex hormones. The sex hormones are under the control of hormones from pituitary gland.
Ques: What are sex- chromosomes?
Ans: The chromosomes which determine the sex in the human beings are called sex- chromosomes. These are two ane is ‘X’ and another ‘Y’. A female has two X chromosomes, while a male has one X and one Y chromosome.
Ques: How does sex-determination take place in human being?
Ans: 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.
Ques: Name a male hormone.
Ans: Testosterone.
Ques: Name a Female hormone.
Ans: Estrogen.
Ques: Which gland is called as master gland?
Ans: Pituitary
Ques: Name the hormone which is responsible for sexual changes in boy.
Ans: Testosterone.
Ques: Name the hormone which is responsible for sexual changes in girls.
Ans: Estrogen.
Ques: what is the reproduction period in lady.
Ans: The reproduction period in lady Starts in age of 10 – 12th years and ends in age of 40 – 45th .
Ques: What is menarche?
Ans: The first The first menstrual flow begins at puberty and is termed menarche.
Ques: What is menstruation?
Ans: The egg release from ovary for fertilisation. 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 bleeding in women which is called menstruation.
Ques: What is menopause?
Ans: At 45 to 50 years of age, the menstrual cycle stops. Stoppage of menstruation is termed menopause.
Additional Questions With Solutions
Additional Questions With Solutions
Ques: What is adolescence?
Ans: Growing up is a natural process. The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence.
Ques: What is the most important change of puberty?
Ans: Boys and girls become capable of reproduction.
Ques: What is the most conspicuous change during puberty?
Ans: The most conspicuous change during puberty is the sudden increase in height.
Ques: Why are endocrine glands called ductless glands?
Ans: Endocrine glands release their hormone directly through the bloodstream not through any duct (pipe), hence these are called ductless glands.
Ques: Why do many people get more acne and pimples on the face during puberty?
Ans: During puberty the secretion of sweat glands and sebaceous glands (oil glands) increases. Many young people get acne and pimples on the face at this time because of the increased activity of these glands in the skin.
Ques: List changes in the body that take place at puberty.
Ans:
(i) Increase in height.
(ii) Change in the body shape – In Boys, shoulders generally broaden as a result of growth. In girls, the region below the waist becomes wider.
(iii) Heaviness in voice.
(iv) Increased Activity of Sweat and Sebaceous Glands.
(v) Development of sex organ – male sex organs like the testes and penis develop completely. In girls, the ovaries enlarge and eggs begin to mature. Also ovaries start releasing mature eggs.
(vi) Reaching Mental, Intellectual and Emotional Maturity.
(vii) Secondary sexual characters – Development of sexual organ as well as they produce sperm and ovum. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, moustaches and beard. Hair grows under the arms and in the region above the thighs or the pubic region.
Ques: What is Secondary sexual characters?
Ans: Development of sexual organ as well as they produce sperm and ovum. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, moustaches and beard. Hair grows under the arms and in the region above the thighs or the pubic region.
Ques: Name the substances which are responsible for physical changes in the body secreted by exocrine glands.
Ans: Hormone.
Ques: What is menstruation?
Ans: The ovary releases eggs for fertilization. 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 bleeding in women which is called menstruation.
Ques: What are the sex hormones? Why are they named so? State their function.
Ans: Testes and ovary are even exocrine glands, which secrete sex hormone. These are responsible for secondary sexual characters so these are called sex hormones. The sex hormones are under the control of hormones from pituitary gland.
Ques: What are sex- chromosomes?
Ans: The chromosomes which determine the sex in the human beings are called sex- chromosomes. These are two ane is ‘X’ and another ‘Y’. A female has two X chromosomes, while a male has one X and one Y chromosome.
Ques: How does sex-determination take place in human being?
Ans: 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.
Ques: Name a male hormone.
Ans: Testosterone.
Ques: Name a Female hormone.
Ans: Estrogen.
Ques: Which gland is called as master gland?
Ans: Pituitary
Ques: Name the hormone which is responsible for sexual changes in boy.
Ans: Testosterone.
Ques: Name the hormone which is responsible for sexual changes in girls.
Ans: Estrogen.
Ques: what is the reproduction period in lady.
Ans: The reproduction period in lady Starts in age of 10 – 12th years and ends in age of 40 – 45th .
Ques: What is menarche?
Ans: The first The first menstrual flow begins at puberty and is termed menarche.
Ques: What is menstruation?
Ans: The egg release from ovary for fertilisation. 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 bleeding in women which is called menstruation.
Ques: What is menopause?
Ans: At 45 to 50 years of age, the menstrual cycle stops. Stoppage of menstruation is termed menopause.
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