CBSE Class 10 Science 2020 · Paper 31/1/1 · Question 3
Answer question numbers 3(a) to 3(d) and 4(a) to 4(d) on the basis of your understanding of the following paragraphs and the related studied concepts.
The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. Reproduction is the process by which organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body growth is still going on. Some degree of sexual maturation does not necessarily mean that the mind or body is ready for sexual acts or for having and bringing up children. Various contraceptive devices are being used by human beings to control the size of population.
- (a)List two common signs of sexual maturation in boys and girls.[1]
- (b)What is the result of reckless female foeticide ?[1]
- (c)Which contraceptive method changes the hormonal balance of the body ?[1]
- (d)Write two factors that determine the size of a population.[1]
Answer
Signs: body hair and oily skin; foeticide lowers the child sex ratio; oral pills change hormones; birth and death rates fix population size.
(a) Any two of: thick hair growth in the armpits and the genital area; thinner hair on the arms, legs and face; oily skin because the oil glands become more active; pimples.
(b) The child sex ratio falls: fewer girls are born than boys, so the male–female ratio of the population becomes imbalanced.
(c) Oral contraceptive pills, the hormonal method.
(d) The birth rate and the death rate.
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