Why are some substances biodegradable and some non-biodegradable?
Some substances are biodegradable and some are non- biodegradable because some microbial actions, radiations and some pollutants may get biologically magnified as they passed through the food chain and some bacteria and the decomposers have a specific role to play.
Like, biodegradable substances (like paper, wood) are those which are degraded naturally. These can disposed by the action of microbes and the radiations. And, non- biodegradable substances are those which cannot be degraded or if degradation occurs, it will be very slow in the process. Non- biodegradable substances are man- made products like D.D.T (Dichloro- diphenyl- trichloroethane), glass, heavy metals, tins, radioactive materials and plastics.
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
What is ozone and how does it affect any ecosystem?
How can you help in reducing the problem of waste disposal? Give any two methods.
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?
The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
What are alloys?
What is the principle of an electric motor?
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
Why does the Sun appear reddish early in the morning?
The anther contains
(a) sepals.
(b) ovules.
(c) pistil.
(d) pollen grains.
What is the far point and near point of the human eye with normal vision?
A solution of a substance 'X' is used for whitewashing.
(i) Name the substance 'X' and write its formula.
(ii) Write the reaction of the substance 'X' named in (i) above with water.
What is the difference between displacement and double displacement reactions? Write equations for these reactions.