• Adolescence:It is the period of 11 to 19 years of age during which the body undergoes different changes, leading to reproductive maturity.
  • Puberty:The age in which human body undergoes several changes and the boys and girls show their capability to reproduce.
  • Adam's Apple:This is the protruding part of the throat in boys which begin to grow at puberty. This is also known as voice box or the larynx.
  • Hormones:These are chemical substances which are secreted from endocrine glands.
  • Testosterone:This is the male sex hormone released by the testes at the onset of puberty.
  • Estrogen:This is the female sex hormone produced by ovaries which the development of breasts develop.
  • Chromosomes:These are thread like structures that is present inside the nucleus of a cell and meant for carrying information from one generation to next generation.
  • Ductless Glands:A few glands such as sweat glands, oil glands and salivary glands release their secretions through ducts. Endocrine glands release hormones directly into the blood stream. So they are also called Ductless glands.
  • Target Site:Endocrine glands release hormones with the bloodstream to reach a particular body part called Target site.
  • Menstruation:If fertilisation does not occur, the released egg, and the thickened living of the uterus along with its blood vessels are shed off. This causes bleeding in women which is called Menstruation.
  • Menopause:At 45 to 50 years of age the menstrual cycle stops. Stoppage of menstruation is termed called Menopause.
  • Endocrine Glands:There are certain glands that are responsible for the secretion of chemical substance called hormones. They pour their secretion directly into the blood stream are called endocrine gland.
  • Pituitary Gland:It is the gland that secretes hormones which include growth hormone and hormones that make other glands such as the testes, ovaries, thyroids and adrenals, to secrete hormones. It is also called as master gland.
  • Adrenalin:It is the hormone secreted by Adrenalin glands that helps the body to adjust to stress, when one is very hungry, embarrassed or worried.

Q.1. What is the term used for secretions of endocrine glands responsible for changes taking place in the body?
Ans. Puberty.
Q.2. Define adolescence.
Ans.  The period of life, when the body undergoes changes, leading to reproductive maturity is called adolescence.
Q.3. What is menstruation? Explain.
Ans. Adolescents become capable to undergo reproduction when their testes and ovaries begin to produce gametes. The capacity for maturation and production of gametes lasts for a much longer time in males then in females. The ova begins to mature with the on set of puberty. One ovum matures and is released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus become thick and so freshly as to receive the egg. In case it is fertilised and begins to develop. This is known as 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 bleeding in women which is called menstruation.
Q.4. List changes in the body that take place at puberty.
  1. Boys and girls become capable of reproduction.
  2. Sudden increase in height.
  3. The bones of the arms and the legs elongate and make a person tall.
  4. The voice of boys becomes hoarse.
Q.5. Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.
Column AColumn B
Name of endocrine glandsName of hormones
  1. Pituitary gland
  2. Thyroid
  3. Adrenals
  4. Pancreas
Testosterone (male)
Estrogen (female)
Q. 6. What are sex hormones? Why are they named so? State their function.

Ans.The hormones secrete from testes and ovaries are called sex hormones.
           The male hormone or testosterone begins to be released by the testes, and the female hormone or estrogen to be released by the ovaries.

Function of male sex hormones/female sex hormones

The male hormone begin changes in boys like growth of facial hair, that is moustaches and beard. Boys also develop hair on their chest and under the arms. The female hormone or estrogen which develop the breasts. Milk secreting glands or mammary glands develop inside the breasts. Girls also develop hair under the arms.
Q.7. Choose the correct option.

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

  1. proper diet develops their brains.
  2. proper diet is needed for the rapid growth taking place in their body.
  3. adolescents feel hungry all the time.
  4. taste buds are well developed in teenagers
Ans.  ii. proper diet is needed for the rapid growth taking place in their body.
        (b) Reproductive age in women starts when their
  1. menstruation starts
  2. breasts start developing.
  3. body weight increases.
  4. height increases.
Ans.  i. menstruation starts.
       (c) The right meal for adolescents consists of
  1. chips, noodles, coke.
  2. chapati, dal, vegetables.
  3. rice, noodles and burger.
  4. vegetable cutlets, chips and lemon drink.
Ans.   ii.Chapati, dal, vegetables.
Q.8. Write notes on:
  1. Adam’s apple.
  2. Secondary sexual characters.
  3. Sex determination in the unborn baby.
Ans.  a) Adam’s Apple: At puberty, the voice box or the larynx begins to grow. Boys develop larger voice boxes. The growing voice box in boys can be seen as a protruding part of the throat called Adam’s apple. In girls the larynx is hardly visible from the outside because of its small size. Generally, girls have a high pitched voice, whereas the boys have a deep voice.
b) Secondary Sexual Characters: We know that testes and ovaries are the main reproductive organs i.e., the primary sex-organs. They produce the  gametes that is sperms and ova. In girls breasts begin to develop at puberty and boys begin to grow facial hair, that is moustaches and beard. As these features help to distinguish the male from the female, so they are called as secondary sexual characters. Boys develop hair on their chest. In bays and girls, hair grows under the arms and in the region above the thighs or the pubic region.
c) Sex Determination in the Unborn Baby: All human beings have 23 pairs of chromosomes as the names X and Y. A female has two X chromosomes, while male has one X and one Y chromosomes. 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. Now you know that the sex chromosomes of the father determine the sex of a baby.


                                       Boy                                          Girl
Fig. 10.1 Sex determination in humans
Q.9. Word game: Use the clues to work out the words.
  1. Protruding voice box in boys
  2. Glands without ducts
  3. Endocrine gland attached to brain
  4. Secretion of endocrine glands
  5. Pancreatic hormone
  6. Female hormone
  1. Male hormone
  2. Secretes thyroxine
  3. Another term for teenage
  4. Hormone reaches here through blood stream
  5. Voice box
  6. Term for changes at adolescence.

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.Initially boys grow faster than girls from 0-8 year but on the basis of above data girls grow faster than boys from year 8 to 12. But 16 year of age, both reach their maximum height, and after that 20th year boys shows higher height than girls.
Q.1. What indicates that a child is becoming an adult?
Ans.The changes taking place in the body indicate that a child is becoming an adult.
Q.2. What is the period of adolescence?
Ans.Period of adolescence covers the ‘teens’ i.e., 13 to 18 or 19 years of age.
Q.3. Which hormones controlled metamorphosis in insects?
Ans.Insects hormones controlled metamorphosis in insects.
Q.4. How many pairs of chromosomes found in nuclei of their cells?
Ans.23 pairs.
Q.5. Give the name of disease caused by the lack of thyroxine?
Q.6. Define the term “Menarche”?
Ans.The first menstrual flow begins at puberty and is termed as Menarche.
Q.7. At what age does the growth in human body become noticeable?
Ans.Crossing the age of 10 or 11 years, a sudden spurt in growth in human body becomes noticeable.
Q.8. What is puberty?
Ans.Puberty is the beginning of adolescence age when human body undergoes several changes.
Q.9. Is mother is responsible for the sex determination of the baby?
Ans.No, father is responsible for the sex determination 'of the baby as being Heterogametic.
Q.10. Do the boys and girls undergo same physical changes during adolescence?
Ans.The boys and girls undergo different physical changes during adolescence, because it is sexual dimorphism in human.
Q.11. Why do many young people get acne during adolescence?
Ans.During puberty, the secretion of sweat glands and sebaceous glands (oil glands) increases. Which gives rise to acne in many young people.
Q.12. When does ovulation occur during the menstrual cycle in a normal healthy woman?
Ans.Ovulation occurs towards the end of proliferative phase, roughly 12 to 14 days of menstruation cycle.
Q.13. What is the function of adrenalin hormone?
Ans.It helps the body to adjust with the stress when one is in anger, embarrased or worried.
Q.14. What do you mean by balance diet?
Ans. A balanced diet means that the meals include all the nutrients like proteins, carbohydrates, fats and vitamins in requisite proportions.
Q.15. Which type of food are good for adolescents?
Ans.Leafy vegetables, jaggery, meat, citrus, milk, fruits, grains, amla etc. are good for the adolescents.

Fig. 10.3. Nutritious items of food
Q.16. What is the most important change during puberty?
Ans.The most important change which become the marks puberty in boys and girls is that they become capable of the process reproduction.
Q.17. When does a child gain maximum height?
Ans.There is a sudden increase in height during puberty. By the time puberty ends, a child becomes adult and achieves 100% of his/her full height.
Q.18. Why the presence of iodine in water is required for the proper growth of tadpoles?
Ans.Thyroxine production requires the presence of iodine in water. If the water in which the tadpoles are growing does not contain sufficient iodine, the tadpoles cannot become an adults.
Q.19. What factors affect the growth in a person?
Ans.The growth in a person depends on
  1. genes inherited from parents.
  2. the kind of diet eaten during the growing years.
Q.20. Why does boys have a hoarse voice at puberty?
Ans.At puberty, the voice box or larynx begins to grow. This growing voice box in boys can be seen as a protruding part of throat called Adam’s apple. This leads to voice becoming hoarse.
Q.21. Why do some adolescents feel insecure?
Ans.Adolescents become more independent and self-conscious. They spend considerable time thinking. But sometimes they are unable to adjust to the changes in body and mind, hence they feel insecure.
Q.22. What are the functions performed by testes in human beings?
Ans.The testes are responsible for
  1. production of sperms.
  2. secretion of the hormone testosterone.
Q.23. Explain the reproductive health.
Ans.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. During adolescence, however, these become even more essential as the body is growing.
Q.24. What is the rate of increase in height in adolescence?
Ans.The rate of growth in height varies from person to person. Some may grow suddenly at puberty and then the growth rate slow down, but in others, it may shows a gradually increase in height.
Q.25. How can young boys and girls take care of their personal hygiene?
Ans.(1) Everyone should have a bath daily because increased activity of sweat glands makes the body smelly.
(2) Girls should take special care of cleanliness during the time of menstrual flow.
Q.26. Show the endocrine glands in the human body.

Fig.10.4.Position of endocrine glands in the human body
Q.27. Write the name and function of one male and one female sex hormone.
Ans.(i) Male sex hormone is testosterone which is produced by testes. It produces secondary sexual characters in males and supports the production of sperms.
(ii) Female sex hormone is estrogen which is produced by ovaries. It produces secondary sexual characters in female and prepares uterus for receiving the embryo.
Q.28. What are the changes seen in girls at the time of puberty?
Ans.The various changes that occur into girls at the time of puberty are
  1. hair growth in the armpits and pubic region.
  2. development of mammary glands or breasts.
  3. onset of menstruation cycle due to production of eggs or ova by the ovaries.
  4. increased oil secretion in the skin.
Q.29. Explain the change in body shape of boys and girls.
Ans.Boys of higher classes have broader shoulders and wider chests than boys in junior classes because they have entered the age of puberty. During puberty, the shoulders generally broaden as a result of growth. In case of girls, the region below the waist becomes wider, in respect to the other region.
                 In boys, the muscles of the body grow more prominently than in the girls. Thus, the changes that take place in an adolescent boys and girls are different.
Q.1. Fill in the blanks with the appropriate words:
  1. Children gain height during………….. .
  2. The onset of………… and ……….. of reproductive parts are controlled by hormones.
  3. Hormones are secretions …………. glands.
  4. Pancreas secretes ………..., thyroid produces………….. and adrenals produce ……… .
  5. Testosterone is the …………. hormone.
  6.  …………. of the unborn child depends on whether the zygote has XX or XY chromosomes.
  7. It is important to eat ………... and maintain personal hygiene during adolescence.
Q.2. Match the following items given in Column ‘A’ with that in Column ‘B’:
Column ‘A’Column ‘B’
  1. Pituitary glands
  2. Thyroid
  3. Adrenals
  4. Pancreas
  5. XX chromosomes
  6. XY chromosomes
  1. Thyroxine
  2. Adrenalin
  3. Insulin
  4. Testosterone (male)
  5. Boy
  6. Girl
Q.3. State whether the statements given below are True or False:
  1. Hormones are secreted from endocrine gland.
  2. Adolescence period cover 30-35 years of age.
  3. 23 pair of chlorosomes found in nuclei of the cells.
  4. Testes are responsible for production of sperms.
  5. Stoppage of menstruation is called adolescence.
  6. Mother is responsible for the sex determination of the baby.
Q.4. Choose the correct option in the following questions:
  1. Adolescence is the period of
  2. 5 to 10 years                                       b) 11 to 19 years
  3. 22 to 28 years                                     d) 30 to 40 years
  1. Which term used for secretions of endocrine glands responsible for changes taking place in the body?
a) Adolescence                                       b) Puberty
c) Menstruation                                      d) Insulin
  1. How many pairs of Chromosomes found in nuclei of their cells?
a) 22 pairs                                                b) 23 pairs
c) 24 pairs                                                d) 25 pairs
  1. Children gain height during
a) adolescence                                         b) endocrine
c) balance food                                        d) menarche
  1. Testes secrete
a) thyroxin                                               b) estrogen
c) testosterone                                         d) iodine
  1. Adam’s apple is
a) enlarged larynx                                   b) mammary glands
c) apple of adam                                     d) red apple
  1.  The chemical substances which are secreted from endocrine glands are called
a) puberty                                                b) hormones
c) estrogen                                              d) adolescence
  1. Out of these which one determines the sex of the baby?
a) Hormones                                           b) Chloroplast
c) Chromosomes                                    d) Pituitary gland
  1. What is the stoppage of menstruation called?
a) Menarche                                            b) Menopause
c) Gametes                                              d) Insulin
  1. Which hormone is secreted by adrenal glands?
a) Adrenalin                                           b) Insulin
c) Testosterone                                       d) Estrogen
  1. Reproduction age in women starts when their
a) menstruation starts                             b) breasts start developing
c) body weight increases                        d) height increases
  1. Which is male gonads?
a) Hair                                                    b) Chest
c) Mustache                                           d)  Testis
  1. The beginning of menstruation at puberty is called
a) ovulation                                            b) menstruation
c) menarche                                           d) menopause
  1. In males, the sex chromosome consists
a) one X and one Y                               b) both X and X
c) both Y and Y                                     d) one M and one X
  1.  Production of thyroxin requires
a) sodium                                              b) magnesium
c) iodine                                                d) bromine
Q.1.Fill in the blanks:
  1. adolescence                                          ii. puberty, maturity
  2. endocrine                                             iv. insulin, thyroxine, adrenalin
  3. male                                                     vi. Sex
  4. balanced food.
Q.2. Match the items under Column ‘A’ with Column ‘B’:
Column ‘A’Column ‘B’
  1. Pituitary glands
  2. Thyroid
  3. Adrenals
  4. Pancreas
  5. XX chromosomes
  6. XY chromosomes
  1. Testosterone (male)
  2. Thyroxine
  3. Adrenalin
  4. Insulin
  5. Girl
  6. Boy
Q. 3. True or False:
     i) True                 ii) False                iii) True                  iv) True            
    v) False          
Q.4. Choose the correct option:
      (i) (b)                   (ii) (b)                  (iii) (b)                (iv) (a)                   (v) (c)
    (vi) (a)                 (vii) (b)                 (viii) (c)               (ix) (b)                   (x) (a)
    (xi) (a)                 (xii) (d)                 (xiii) (c)              (xiv) (a)                 (xv) (c).