10. Reaching the age of adolescence Science class 8 in English Medium ncert book solutions Addtional - Question

Additional Questions With Solutions

Ques: What is adolescence?

Ans: Growing up is a natural process. The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence.

Ques: What is the most important change of puberty?

Ans:  Boys and girls become capable of reproduction.

Ques: What is the most conspicuous change during puberty?

Ans: The most conspicuous change during puberty is the sudden increase in height.

Ques: Why are endocrine glands called ductless glands?

Ans: Endocrine glands release their hormone directly through the bloodstream not through any duct (pipe), hence these are called ductless glands.

Ques: Why do many people get more acne and pimples on the face during puberty?

Ans: During puberty the secretion of sweat glands and sebaceous glands (oil glands) increases. Many young people get acne and pimples on the face at this time because of the increased activity of these glands in the skin.

Ques: List changes in the body that take place at puberty.

Ans:

(i) Increase in height.

(ii) Change in the body shape – In Boys, shoulders generally broaden as a result of growth. In girls, the region below the waist becomes wider.

(iii) Heaviness in voice.

(iv) Increased Activity of Sweat and Sebaceous Glands.

(v) Development of sex organ – male sex organs like the testes and penis develop completely. In girls, the ovaries enlarge and eggs begin to mature. Also ovaries start releasing mature eggs.

(vi) Reaching Mental, Intellectual and Emotional Maturity.

(vii) Secondary sexual characters – Development of sexual organ as well as they produce sperm and ovum. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, moustaches and beard. Hair grows under the arms and in the region above the thighs or the pubic region.

Ques: What is Secondary sexual characters?

Ans: Development of sexual organ as well as they produce sperm and ovum. In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is, moustaches and beard. Hair grows under the arms and in the region above the thighs or the pubic region.

Ques: Name the substances which are responsible for physical changes in the body secreted by exocrine glands.

Ans: Hormone.

​Ques: What is menstruation?

Ans: The ovary releases eggs for fertilization. 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.

Ques: What are the sex hormones? Why are they named so?     State their function.

Ans: Testes and ovary are even exocrine glands, which secrete sex hormone. These are responsible for secondary sexual characters  so these are called sex hormones. The sex hormones are under the control of hormones from pituitary gland.

Ques: What are sex- chromosomes?

Ans: The chromosomes which determine the sex in the human beings are called sex- chromosomes. These are two ane is ‘X’ and another ‘Y’. A female has two X chromosomes, while a male has one X and one Y chromosome.    

Ques: How does sex-determination take place in human being?

Ans: 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.

Ques: Name a male hormone.

Ans: Testosterone.

Ques: Name a Female hormone.

Ans: Estrogen.

Ques: Which gland is called as master gland?

Ans: Pituitary

Ques: Name the hormone which is responsible for sexual changes in boy.

Ans: Testosterone. 

Ques: Name the hormone which is responsible for sexual changes in girls.

Ans: Estrogen.

Ques: what is the reproduction period in lady.

Ans: The reproduction period in lady Starts in age of 10 – 12^th  years and ends in age of 40 – 45^th .

Ques: What is menarche?

Ans: The first The first menstrual flow begins at puberty and is termed menarche.

Ques: What is menstruation?

Ans: The egg release from ovary for fertilisation. 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.

Ques: What is menopause?

Ans: At 45 to 50 years of age, the menstrual cycle stops. Stoppage of menstruation is termed menopause.