Solved examples for class 8 science : Chapter 10

    Reaching the Age of Adolescence

    I. Multiple Choice Questions (MCQs).
    Q.1. A stage of physical and mental development that occurs between childhood and adulthood, is
    a) Adolescence
    b) teenagers
    c) growing up children
    d) ( d) none of these
    Answer. a) adolescence

    Q.2. In boys the protruding part of the throat is known as
    a) larynx
    b) voice box
    c) Adam’s Apple
    d) none of these
    Answer. c) Adam’s Apple

    Q.3. The end of menstrual cycle in human female is called
    a) puberty
    b) adolescents
    c) menarche
    d) menopause
    Answer. ( d) menopause

    Q.4. Which of the following combination of chromosomes leads to the birth of a baby girl?
    a) XY
    b) XX
    c) YY
    d) X
    Answer. (b) XX

    Q.5. The right diet for adolescents consists of
    a) chips, chapati and noodles
    b) rice, burger and coke
    c) vegetable cutlet, chips and soft drinks
    d) Chapati, dal and vegetables

    Answer. d) Chapati, dal and vegetables

    II. Fill in the blanks by selecting appropriate words from the given list : List : adolescence, emotional, larynx, hormones, goitre

    Q.1. Adolescence and puberty bring with a lot of ……………………. baggage.
    Q.2. In girls the………………………. is not clearly visible from outside.
    Q.3. The changes are different in girls and boys during ……………………
    Q.4. The…………………………… are responsible for the excess release of oil glands and sweat glands.
    Q.5. Due to insufficient secretion of thyroxine a person can suffer from a disease called……………………………..
    Answer.
    1- emotional,
    2- larynx,
    3- adolescence,
    4- hormones,
    5- goitre

    III. Match the items of Column A with those of Column B.


    Answer. 1-, 2-a, 3-d, 4-b, 5-c

    IV. Write ‘T’ for the true and ‘F’ for the false statements.
    Q.1. Puberty is a biological process characterised by the maturation of secondary sexual organs and
    characteristics.
    Q.2. Adolescence stage in girls may begin a year or two earlier than in boys.
    Q.3. Hormones are the chemical substances secreted by the endocrine glands.
    Q.4. All the hormones are secreted under the control of hormone secreted by thyroxine gland.
    Q.5. Scientifically the chromosome of father determines the sex of a baby.

    Answer. 1-T, 2-T, 3-T, 4-F, 5-T

    V. Very Short Answer Questions.

    Q.1. Write the average ages for girls and boys of puberty.

    Answer: The average age for girls of puberty is 10-12 years while for boys it is 12-14 years.

    Q.2. What hormones are responsible for rapid growth and secondary sexual characteristics?
    Answer: The hormones responsible for rapid growth and secondary sexual characteristics are the growth hormones and the sex hormones respectively.

    Q.3. How do hormones released by the glands reach a particular part or organ?
    Answer: Glands release hormones direct to the blood so that to reach a particular part or organ.

    Q.4. Name the master gland.
    Answer: The pituitary gland also known as master gland.

    Q.5. Name the hormone secreted during stress or when a person feels very angry.

    Answer: During the stress or when a person feels very anger, adrenal gland secretes a hormone called adrenaline.

    VI. Short Answer Questions.
    Q.1. What are the changes in body shape of boys and girls during adolescence?
    Answer. During adolescence the shoulders of boys become broader and the chest become wider. This is because they have entered the age of puberty. On the other hand in girls the region below the waist becomes broader. The changes are different in girls and boys that occur during adolescence.
    The muscles grow more prominently in boys.
    Q.2. What will happen if egg is fertilised?
    Answer: If the egg is fertilised, it begins to develop, this is called pregnancy, but if the fertilisation of egg fails, the thick lining of the uterus along with blood shed off.

    Q.3. What is AIDS? How does it affect our immune system?

    Answer. AIDS is a chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV). HIV attacks on our immune system so that immune system becomes weak.

    Q.4. Discuss development of secondary sexual characters during adolescence stage.

    Answer: In females, the ovariesrelease the female hormone i.e., estrogen, which enhances the breast development. The mammary glands (milk secreting glands) develop inside the breasts. In males, the testes release the male hormone i.e. testosterone which is responsible for the development of secondary sexual characters. All these hormones are secreted under the control of another hormone secreted by pituitary gland.

    Q.5. Describe reproductive functions of hormones in human.

    Answer. The testes release sex hormone testosterone in male while in female the ovaries release estrogen. The sex hormones are responsible for male and female secondary sexual characters. The hormones secreted by pituitary gland stimulate the secretion and activity of sex hormones. Both the sex hormones released in the blood stream, reach different parts of the body or target sites. As a result they stimulate the changes in the body at onset of puberty.

    Q.6. How is sex determined? Explain with examples.
    Answer. An unfertilized egg has 22 chromosomes (autosomes) and one sex chromosome (X) while a sperm has 22 chromosomes (autosomes) and one Y or X chromosome. So all the eggs are similar but the sperms are of two kinds. When an egg is fertilised by a sperm containing X chromosome, the zygote will have two X chromosomes and it will develop into a baby girl. But if the egg is fertilized by a sperm containing Y chromosome, the zygote will have XY chromosomes and it will develop into a baby boy.

    VII. Long Answer Questions.

    Q.1. What do you mean by adolescence and puberty?
    Answer: Adolescence is a stage of physical and mental development that occurs between childhood and adulthood. This development involves biological, social and psychological changes. During this period a person’s body undergoes dramatic changes. In girls adolescence stage may begin one year or two years earlier than in boys. The period of adolescence differs from person to person.

    Puberty is a biological process characterised by the maturation of secondary sexual organs and characteristics. The average age for girls of puberty is 10-12 years while for boys it is 12-14 years. In simple words, puberty is the time when a child’s body starts changing into an adult body. Adolescence and puberty bring with a Lot of emotional baggage.

    Q.2. What do you understand by reproductive phase in humans? Explain briefly.

    Answer: The adolescent boys become capable of reproduction when their testes begin to produce sperms and the girls capable of reproduction when their ovaries begin to produce ova. In males, the capacity for maturation and production of gametes (sperms) lasts for a longer time (duration) than in females. In females (girls) the reproductive phase begins at the age of 1 0 to 12 years and generally lasts upto the age of nearly 45 to 50 years. At the onset of puberty, the ova begin to mature and once in 28 days a mature ova is released. The uterus wall becomes thick to prepare itself for receiving the egg. If the egg is fertilised, it begins to develop, this is called pregnancy, but if the fertilisation of egg fails, the thick lining of the uterus along with blood shed off. This process is called menstruation and occurs once in 28. days. The first menstrual flow begins at puberty, called menarche. It stops at the age of 45 to 50 years and is called menopause.

    Q.3. Discuss reproductive health of adolescents. Explain some requirements for them.

    Answer: The term ‘Reproductive health’ refers to healthy reproductive organs by structurally and functionally. According to World Health Organisation (WHO), reproductive health is defined as the complete physical and mental well-being of an individual in all aspects of reproduction. To remain healthy, a balanced diet is needed for an individual at all stages of life. During adolescence, a nutritious or balanced diet become more essential to remain healthy in all aspects of reproduction because it is a stage of rapid growth and development. A woman during menstruation loses blood and for that they need more iron in the balanced diet. Even during pregnancy, women need balanced diet for a healthy baby.

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