Question 1

Question 1What is the term used for chemical secretions of endocrine glands responsible for changes taking place in the body?

Accepted Answer

The term used for chemical secretions of endocrine glands responsible for changes taking place in the body are Hormones.

Question 2

Question 2Define adolescence.

Accepted Answer

The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. In other words, adolescence is transitional phase of growth and development between childhood and adulthood.

Question 3

Question 3What is menstruation? Explain.

Accepted Answer

In females, with the onset of puberty, the ova begins to mature. 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 becomes thick so as to receive the egg. 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. Menstruation occurs once in about 28 to 30 days.

Question 4

Question 4List changes in the body that take place at puberty.

Accepted Answer

Following are the changes that take place at puberty :Body becomes capable of reproduction.Sudden increase in height.Growth in shoulders and muscles in boysChange in voice and protruding voice box or the larynx in boysThe secretion of sweat glands and sebaceous glands (oil glands) increases causing acne.At puberty, male sex organs like the testes and penis develop completely. The testes also begin to produce sperms.Boys begin to grow facial hair, that is, moustaches and beard. Boys also develop hair on their chest, underarm and pubic area.Development of breast in girls.In girls, the region below the waist becomes wider.Ovary matures and begin to release egg.Girls develop hair in underarm and pubic area.

Question 5

Question 5Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.

Accepted Answer

Below table shows the names of endocrine glands and hormones secreted by them:Endocrine glandHormonesTestisTestosteroneOvaryOestrogenThyroidThyroxinAdrenalAdrenalinPituitaryGrowth hormonePancreasInsulin

Question 6

Question 6What are sex hormones? Why are they named so? State their function.

Accepted Answer

Hormones released from sex organs are referred as sex hormones. They are named so because they affect the sexual organs and characters.The sex hormones and their functions are as follows :Male sex hormone is Testosterone released from testis. Testosterone induces puberty-related physical changes, including increased muscle, face, pubic, and body hair growth, voice deepening, and sexual and reproductive development.Female sex hormone is estrogen which is released from ovary. It plays role in maintenance of menstrual cycle, development of breast.

Question 7

Question 7(a)Adolescents should be careful about what they eat, becauseproper diet develops their brains.proper diet is needed for the rapid growth taking place in their body.adolescents feel hungry all the time.taste buds are well developed in teenagers.

Accepted Answer

proper diet is needed for the rapid growth taking place in their body.Reason — Adolescence is a period of rapid growth. Therefore, a proper growth requires ample of nutrition.

Question 8

Question 7(b)Reproductive age in women starts when theirmenstruation starts.breasts start developing.body weight increases.height increases.

Accepted Answer

menstruation starts.Reason — Start of menstruation marks end of puberty and start of reproductive age.

Question 9

Question 7(c)The right meal for adolescents consists ofchips, noodles, coke.chapati, dal, vegetables.rice, noodles and burger.vegetable cutlets, chips and lemon drink.

Accepted Answer

chapati, dal, vegetables.Reason— Junk food will not provide the required amount of nutrition.

Question 10

Question 8Write notes on :(a) Adam's apple.(b) Secondary sexual characters.(c) Sex determination in the unborn baby.

Accepted Answer

(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. Sometimes, the muscles of the growing voice box go out of control and the voice becomes hoarse. This state may remain for a few days or weeks after which the voice becomes normal.(b) Secondary sexual characters — Secondary sexual characters are responsible for the features that help to distinguish the male from the female. Secondary sexual characters in boys are development of pubic hair, facial hair and hair on chest. Development of breast in girls is also a secondary sexual character.(c) Sex determination in the unborn baby — All human beings have 23 pairs of chromosomes in the nuclei of their cells. Two chromosomes out of these are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only one set of chromosomes. The unfertilised 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.

Question 11

Question 9Word game : Use the clues to work out the words.Across3. 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.Down1. Male hormone.2. Secretes thyroxine.3. Another term for teenage.5. Hormone reaches here through blood stream.6. Voice box.7. Term for changes at adolescence.

Accepted Answer

The solution of word puzzle is given below:Across3. Adam's Apple.4. Endocrine.7. Pituitary.8. Hormone.9. Insulin.10. Estrogen.Down1. Testosterone.2. Thyroid.3. Adolescence.5. Target Site.6. Larynx.7. Puberty.

Question 12

Question 10The 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?

Accepted Answer

The following conclusions can be drawn from these graphs:From 0 to 8 years, height of boys increases more than girls so boys are generally a little taller than girls in this age group.Both boys and girls experience a sudden increase in height during puberty.At the onset of puberty when the adolescence period starts (around 12 years), height of girls show a sudden increase and they become taller than boys.Around the age of 16, height of boys catches up with girls and both are equally tall.Afterwards, the height increases and becomes stable around 20 years of age with height of boys being a little more than girls.

Reaching the Age of Adolescence