Question 1: What
is the term used for secretions of endocrine glands responsible for changes
taking place in the body?
Answer: Hormones are chemical
substances which are secreted by endocrine glands. They are responsible for
changes taking place in the body.
Question 2: Define
adolescence.
Answer: Adolescence is the time
period between the beginning of puberty and adulthood. During this period, the
body undergoes several changes alongside reproductive maturity. It begins
around the age of 11 and lasts till 18 or 19 years of age. The period of
adolescence may vary from person to person.
Question 3: What
is menstruation? Explain.
Answer: Menstruation is the
process of the shedding of the uterine lining on a regular monthly basis. It
begins at puberty and is the reproductive cycle of the female body. Every
month, the uterus prepares itself to receive a fertilized egg. Therefore, the
inner lining of the uterus becomes thick and is supplied with blood to nourish
the embryo. If the egg is not fertilized, then the lining of the uterus breaks
down and gets released in the form of blood through the vagina. This lasts for
about two to eight days. This cycle occurs every month and is known as the
menstrual cycle.
Question 4: List
changes in the body that take place at puberty.
Answer: Changes at puberty: (i)
Sudden increase in height and weight.
(ii) Broadening of shoulders and widening of chest in boys.
In girls, the region below waist becomes wider.
(iii) In boys, under the influence of hormones, the larynx
becomes prominent, the vocal cords become longer and thicker. These changes
cause the voice to become hoarse.
(iv) Appearance of hair in areas such as underarms, face,
hands, and legs.
(v) Appearance of acne as a result of excessive secretion of
oil from skin.
(iv) Testis grows and starts producing sperms in males,
whereas in females, the ovary enlarges and starts producing matured eggs.
Question 5: Prepare
a table having two columns depicting names of endocrine glands and hormones
secreted by them.
Answer:
Endocrine gland
|
Hormones
|
Testis
|
Testosterone
|
Ovary
|
Oestrogen
|
Thyroid
|
Thyroxin
|
Adrenal
|
Adrenalin
|
Pancreas
|
Insulin
|
Pituitary
|
Growth hormone
|
Question 6: What
are sex hormones? Why are they named so? State their function.
.Answer: Sex hormones are chemical substances produced by sex organs. For example, testosterone is the male sex hormone produced by the testis, and oestrogen is the female sex hormone produced by the ovary. These hormones affect the sexual features of an organism. Hence, they are known as sex hormones. Functions of sex hormones: Testosterone: This hormone brings about secondary sex characters in boys such as the growth of a beard, the voice becoming hoarse, development of reproductive organs, etc. Oestrogen: This hormone is responsible for the development of secondary sexual characters in females such as the enlargement of breasts, development of female reproductive organs, etc.
Question 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) chapatti, dal, vegetables. (iii) rice, noodles and burger.
(iv) vegetable cutlets, chips and lemon drink.
Answer:
(a) (ii) Adolescents should be careful about what they eat,
because proper diet is needed for the rapid growth taking place in their body.
(b) (i) Reproductive age in women starts when their
menstruation starts.
(c) (ii) The right meal for adolescents consists of
chapatti, dal, vegetables.
Question 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. However, in females, the larynx is of a small size and is hardly
visible. Therefore, girls have a high pitched voice, while the voice of boys is
low pitched.
(b) Secondary sexual characters are
those features that help in distinguishing the male and the female body from
each other. They are physical or behavioural 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 character
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.
(c) Sex determination in an unborn baby:
The sex of a baby is determined by the type of male gamete that fuses with the
female gamete. All human beings have 23 pairs of chromosomes in their nuclei.
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 or 22+Y Females have 23 pairs of chromosomes
including XX sex chromosomes. Therefore, their gametes can only have 22
chromosomes and one X sex chromosome. Type of female gametes: 22+X
Thus, as the mother
provides only X chromosome, the sex of the baby is determined by the type of
male gamete (X or Y) that fuses with the X chromosome of the female.
Question 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 thyroxin
3. Another term for teenage
5. Hormone reaches here through blood stream
6. Voice box
7. Term for changes at adolescence
Answer:
Across
3. ADAM’S APPLE
4. ENDOCRINE
7. PITUITARY
8. HORMONE
9. INSULIN
10. ESTROGEN
Down
1. TESTOSTERONE
2. THYROID
3. ADOLESCENCE
5. TARGET SITE
6. LARYNX
7. PUBERTY
Question 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?
Age (Years)
|
Height (cm)
|
|
Boys
|
Girls
|
|
0
|
53 53
|
|
4
|
96 92
|
|
8
|
114 110
|
|
12
|
129 113
|
|
16
|
150 150
|
|
20
|
173 165
|
|
Answer: The graph
depicts the relation between the age and height of both boys and girls. During
puberty, there is a sudden increase in height of both boys and girls. On the
basis of the above graph, it can be observed that during the age of 4-8 years,
girls have less height as compared to boys. However, as soon as girls reach 12-
13 years, their height shows a sudden increase and becomes more than boys. In
later years, growth in both sexes becomes stable. Growth during puberty is
under the control of hormones.
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