Class 10 Science - Chapter Our Environment NCERT Solutions | Why are some substances biodegradable an

What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

Give any two ways in which biodegradable substances would affect the environment.

Which of the following constitute a food-chain?

(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat

If all the waste we generate is biodegradable, will this have no impact on the environment?

Which of the following groups contain only biodegradable items?

(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass

How can you help in reducing the problem of waste disposal? Give any two methods.

What is ozone and how does it affect any ecosystem?

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

What is the role of decomposers in the ecosystem?

What will happen if we kill all the organisms in one trophic level?

Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.

What is a good source of energy?

Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

What changes can you make in your habits to become more environment-friendly?

What is the difference between a reflex action and walking?

What is the importance of DNA copying in reproduction?

If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Why should a magnesium ribbon be cleared before burning in air?

Define the principal focus of a concave mirror.

You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?

Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

Name a mirror that can give an erect and enlarged image of an object.

Describe the structure and functioning of nephrons.

Find out, from Table 10.3, the medium having highest optical density. Also find the medium with lowest optical density.

     Table 10.3 Absolute refractive index of some material media

Can any source of energy be pollution-free? Why or why not?

What is the role of the acid in our stomach?

What are the components of the transport system in human beings? What are the functions of these components?

How do auxins promote the growth of a tendril around a support?

Give an example of a double displacement reaction other than the one given in activity 1.10.

A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as

(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw