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प्रश्न
Use of several pesticides which results in excessive accumulation of pesticides in rivers of ponds, is a matter of deep concern. Justify this statement.
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उत्तर
Several pesticides and other chemicals to protect our crops from diseases and pests. These chemicals are either washed down into the soil or into the water bodies. From the soil, these are absorbed by the plants along with water and minerals, and from the water bodies these are taken up by aquatic plants and animals. This is one of the ways in which they enter the food chain. As these chemicals are not degradable, these get accumulated progressively at each trophic level. As human beings occupy the top level in any food chain, the maximum concentration of these chemicals get accumulated in our bodies. This phenomenon is known as biological magnification. This is the reason why our food grains such as wheat and rice, vegetables and fruits, and even meat, contain varying amounts of pesticide residues. They cannot always be removed by washing or other means. Thus, it is extremely concerning when pesticides are used in large quantities that cause an excessive buildup in rivers or ponds.
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संबंधित प्रश्न
Give reason to justify the following: Flow of energy in a food chain is unidirectional.
Why are green plants called producers?
Give an example of a four step food chain operating in grassland. Name the secondary consumer in this food chain
Write down a food chain with five links in it.
A student went to study a local pond. In one part of the pond she noticed tadpoles scraping at some pond weed. In another part she saw a water beetle holding a tadpole in its jaws.
(a) Construct a food chain for the pond.
(b) How many links are there in this chain?
The surface of water in a lake appears green due to a layer of tiny free-floating organisms X on its surface. The lake water also contains organisms like water beetle, fish and tadpole. The sun shines over the lake water and provides energy for the functioning of this lake ecosystem.
(a) What could organisms X be?
(b) Write a food chain comprising of all the four organisms mentioned.
(c) What is the general name of the food chains like the one written above?
(d) Name (i) secondary consumer (ii) producer (iii) tertiary consumer, and (iv) primary consumer, in the above food chain.
(e) If the tertiary consumer gets 0.2 J of energy from the secondary consumer, then how much energy was radiated by the sun to the producer?
We should reduce the use of the plastic bags, bottles etc. because ______.
Observe the food web and answer the questions given below:
Why do all food chains start with plants?
In a food chain grasshopper gets energy by eating frog.
What will happen if deer is missing in the food chain given below?
Grass → Deer → Tiger
