Lakhmir singh solutions science class 8 Solutions for Chapter 10 reaching the age of adolescence

Exercises in Chapter 10 reaching the age of adolescence Grade 8

Exercise

Questions in Exercise

What is the special name of the period of life between childhood and adulthood?

Name another term for ‘adolescents’.

State the age at which adolescence usually begins and the age up to which it lasts.

Which is the most conspicuous change (clear visible change) in boys and girls during puberty?

How does the height of boys and girls change during puberty?

Name one factor on which the height of a person depends.

A nine-year-old boy is 120 cm tall. If the present height of the boy is 75% of his full height,calculate the full height which the boy will eventually reach at the end of the growth period.

How do shoulders and chest change in boys during puberty?

How do hips of girls change during puberty?

What is the other name of the 'voice box’?

Which of the two have a smaller voice box: grown-up boys or grown-up girls?

What is the common name of the bulge (or projection) at the front of the throat in grown-up boys?

What substance is secreted by sebaceous glands?

Name the time period in one’s life when the brain has the greatest capacity for learning.

Name two glands present in the skin whose increased activity causes pimples and acne.

What name is given to those sexual characteristics in humans: (a) which are present in babies at birth? (b) which develop in mature boys and girls?

Name any two glands which function as endocrine glands as well as exocrine glands.

What is the other name of ductless glands?

What term is used for the secretion of endocrine glands?

Name (a) Female sex hormone, and(b)male sex hormone.

Name the hormone which develops secondary sexual characteristic: (a) in females (girls) (b) in males (boys)

State the function of the male sex hormone ‘testosterone’.

Name the endocrine gland which controls the production of sex hormones ‘testosterone’ and ‘estrogen’.

What is the name of the process in which the thickened uterus lining along with its blood vessels is removed from the body of a woman through vaginal bleeding?

Which comes earlier in the life of a woman: menarche or menopause?

(b) Around which age menopause occurs in woman? (b) Around which age menopause occurs in woman?

State one situation (other than menopause) when ovulation and menstruation stop in a woman.

Which of the two has a shorter reproductive phase of life: men or women?

Which of the following combinations of sex chromosomes products a male child (or boy)? XX or XY

State whether the following statements are true or false (a) The estrogen hormone develops a deeper voice in males at puberty. (b) Menstruation stops in men permanently around the age of 45 to 50 years. (c) Man (father) is responsible for the sex of the body. (d) The sex chromosomes in all the gametes (sperms) of a man are not identical. \ (e) Half the female gametes contain X chromosomes and the other half contain Y chromosomes. (f) It is the sperm that determines the sex of a child. (g) Each normal cell in our body contains 23 chromosomes and the other half contain Y chromosomes. (h) A girl should not be allowed to work in the kitchen during menstruation. (i) A woman (mother) is responsible for the sex of her child. (j) Metamorphosis in insects (like silk moth) is brought about by thyroxine hormone.

Which of the two, sperm or egg cell (ovum), decides the sex of the child?

What is the legal age for the marriage of (a) boys, and (b) girls, in our country?

Name a natural balanced food for infants.

During which time the adolescent girls should take special care of personal hygiene?

Write the full name of (i) AIDS, and (ii) HIV

Write the name of the virus which causes AIDS disease.

Name the endocrine gland attached to the base of the brain.

Name the endocrine gland which secrets the growth hormone.

Name the substance which is needed continuously by the thyroid gland to make thyroxine hormone.

State the main symptom of goiter.

Name the hormone whose deficiency in the body causes goiter.

Name the gland which secretes insulin hormone.

Name the disease caused by the insufficient production of insulin hormones by the pancreas.

Name the hormone which prepares our body for action to face emergency situation like danger, fear, anger or excitement.

Name the endocrine gland which secretes a hormone that maintains correct salt balance in the blood.

Name a hormone (other than adrenalin) secreted by adrenals.

Name the hormone whose deficiency causes diabetes.

Name the hormone which is required for the metamorphosis of larvae (tadpoles) into adult frogs.

Name the hormone which brings about metamorphosis in silk moth and changes caterpillar (larva) into adult silk moth.

Fill in the following blanks with suitable words (a) Sexual maturity is reached at_ (b) The changes which occur in boys and girls at puberty are brought about by various_ (c) Initially, girls grow_than boys. (d) The changes occurring in body and mind during adolescence are a natural part of_up. (e) The features which help us to distinguish between a mature boy and a girl are called_sexual characteristics. (f) The onset of puberty is controlled by_ (g) The menstrual cycle in women is controlled by_ (h) Each normal body cell in humans contains_pairs of chromosomes out of which_pair is of sex chromosomes. (i) X and Y chromosomes are called_chromosomes. (j) Early marriage and motherhood cause health problems in the _________and the_________ (k) The protective foods are _________ and _________ (l) Thyroid and adrenals secrete their hormones when they receive instructions from_________gland through its hormones. (m) Metamorphosis in amphibians is brought about by_________hormone.