Short Answer TypeWhat will be the amount of energy available to the organisms of the 2nd trophic level of a food chain if the energy available at the first trophic level is 10,000 joules?
On applying the 10% law to the food chain, the organisms of the 2nd trophic level of the food chain will have 1000 joules of energy.
List two main causes of the pollution of water of the river Ganga. State how pollution and contamination of river water prove harmful for the health of the people of neighbouring areas.
What is biodiversity? What will happen if biodiversity of an area is not preserved? Mention one effect of it.
What are chromosomes? Explain how in sexually reproducing organisms the number of chromosomes in the progeny is maintained.
List four points of significance of reproductive health in a society. Name any two areas related to the reproductive health which have improved over the past 50 years in our country.
Explain with an example for each, how the following provides evidences in favour of evolution in organisms:
(a) Homologous organs
(b) Analogous organs
(c) Fossils
Differentiate between biodegradable and non-biodegradable substances with the help of one example each. List two changes in habit that people must adopt to dispose nonbiodegradable waste, for saving the environment.
A 4 cm tall object is placed on the principal axis of a convex lens. The distance of the object from the optical centre of the lens is 12 cm and its sharp image is formed at a distance of 24 cm from it on a screen on the other side of the lens. If the object is now moved a little away from the lens, in which way (towards the lens or away from the lens) will he have to move the screen to get a sharp image of the object on it again? How will the magnification of the image be affected?
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