Section A (1 Mark Each)
Question 3: 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 the population.
(a) List two common signs of sexual maturation in boys and girls.
Answer:
Two common signs of sexual maturation in boys and girls are:
- Thick hair growth in armpits, genital area/thinner hair on arms, legs, face.
- More active oil secretion from glands on skin/Occurrence of pimples.
(b) What is the result of reckless female foeticide?
Answer:
Reckless female foeticide causes imbalance in male – female ratio/ decline in child sex ratio.
(c) Which contraceptive method changes the hormonal balance of the body?
Answer:
Oral pills change the hormonal balance of the body.
(d) Write two factors that determine the size of a population.
Answer:
Two factors which determine the size of population are:
- Birth rate
- Death rate
Question 4: Human body is made up of five important components, of which water is the main component. Food as well as potable water are essential for every human being. The food is obtained from plants through agriculture. Pesticides are being used extensively for a high yield in the fields. These pesticides are absorbed by the plants from the soil along with water and minerals and from the water bodies these pesticides are taken up by the aquatic animals and plants. As these chemicals are not biodegradable, they get accumulated progressively at each trophic level. The maximum concentration of these chemicals gets accumulated in our bodies and greatly affects the health of our mind and body.
a) Why is the maximum concentration of pesticides found in human beings?
Answer:
Human beings are at the top level in any food chain. That’s why maximum concentration of pesticides found in human beings.
(b) Give one method which could be applied to reduce our intake of pesticides through food to some extent.
Answer:
Washing of vegetables, fruits, grains thoroughly is one method which could be applied to reduce our intake of pesticides through food to some extent.
(c) Various steps in a food chain represent:
- (a) Food web
- (b) Trophic level
- (e) Ecosystem
- (d) Biomagnification
Answer:
The various steps which are represented in the food chain are known as trophic level. Hence the correct option is (b).
(d) With regard to various food chains operating in an ecosystem, man is a:
- (a) Consumer
- (b) Producer
- (c) Producer and consumer
- (d) Producer and decomposer
Answer:
According to food chains, a man is a consumer which does not produce anything of its own. Hence the correct option is (a).
CBSE Class 10 Previous Year Question Paper (Biology) – 2020
CBSE class 10 previous year question papers helps you to understand the level of questions asked in the previous exams, along with the changes in pattern. Practicing the biology class 10 previous year question papers enhances time-management skills while appearing in the board examination. It makes you understand the importance of different topics that have been asked previously.
CBSE Class 10 pyq Biology will boost your confidence level to appear in the examination with proper knowledge of different topics that are going to be asked. It enhances the understanding of the topic and acts as a checkpoint to see the level of preparation that you have done. CBSE biology previous year question paper 2020 is available here.