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प्रश्न
Explain why, the flow of energy in the ecosystem is said to be unidirectional.
Give scientific reasons:
In an ecosystem, the energy flow is always unidirectional.
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उत्तर
Energy enters plants from the sun during food production through photosynthesis. This energy is then passed on from one organism to another in a food chain. The energy given out by organisms as heat is lost in the environment and does not return to be used by plants again. This makes the flow of energy in an ecosystem unidirectional. Thus, the flow of energy in an ecosystem is said to be unidirectional because the energy lost as heat from the organisms in a food chain cannot be reused by plants in photosynthesis.
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संबंधित प्रश्न
"Energy flow in a food chain is unidirectional" Justify this statement.
The first trophic level in a food chain is always a green plant. Why ?
What is the role of decomposers in the ecosystem?
Give one example of a simple food chain.
Which of the following represents a possible food chain found in a pond :
| Primary producers |
Primary consumers | Secondary consumers |
| (a) green algae | fish | mosquito larvae |
| (b) fish | green algae | mosquito larvae |
| (c) mosquito larvae | fish | green algae |
| (d) green algae | mosquito larvae | fish |
Which of the following group of organisms are not constituents of a food chain?
- grass, lion, rabbit, wolf
- plankton, man, fish, grasshopper
- wolf, grass, snake, tiger
- frog, snake, eagle, grass, grasshopper
A food chain occurring in the sea which provides food for many people can be written as :
phytoplankton → zooplankton → X → Y
Name the organism which Y could be.
What would happen to the number of grass plants and foxes if the number of rabbits decreased?
What is ten per cent law? Explain with an example.
With the help of a food chain, explain how biological magnification of harmful chemicals can occur.
Consider the following food chain
(i) Plants → Mice → Snakes → Hawks
(ii) Plants → Mice →Hawks
If energy available at the producer level in both the food chains is 100 J, in which case will hawks get more energy as food and by how much? Justify your answer.:
If the energy available at the producer level in a food chain is 150 J, how much energy will be transferred to : tertiary consumer?
(a) 15 J
(b) 10 J
(c) 1.50 J
(d) 0.15 J
"Energy flow in food chains is always unidirectional". Justify this statement. Explain how the pesticides enter a food chain and subsequently get into our body.
| 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 biodegradables, 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. |
- Why is the maximum concentration of pesticides found in human beings? (1)
- Give one method which could be applied to reduce our intake of pesticides through food to some extent. (1)
- Various steps in a food chain represent: (1)
- Food web
- Trophic level
- Ecosystem
- Biomagnification
- With regard to various food chains operating in an ecosystem, man is a: (1)
- Consumer
- Producer
- Producer and consumer
- Producer and decomposer
Write the importance of the food chain.
Which of the following is an autotroph?
Natural agents like ______ are the decomposition factors breaking complex forms into simpler units.
The food chain begins with the energy given by the ______.
In the following food chain, vertical arrows indicate the energy lost to the environment and horizontal arrows indicate energy transferred to the next trophic level. Which one of the three vertical arrows (A, C and E) and which one of the two horizontal arrows (B and D) will represent more energy transfer? Give reason for your answer.
A food chain in a forest ecosystem
