A food chain that begins with dead organic matter is called
- A.Grazing food chain
- B.Detritus food chain
- C.Parasitic food chain
- D.Predator food chain
Correct answer
Explanation
The correct answer is B, detritus food chain. Detritus is dead organic matter such as fallen leaves, dead bodies and animal waste. Organisms like earthworms, termites, bacteria and fungi feed on it, and they in turn are eaten by small birds and other animals. In many ecosystems, and especially in forests, a larger share of energy flows through this chain than through the grazing chain.
Option A, the grazing food chain, starts with living green plants, as in the sequence grass, grasshopper, frog, snake. Options C and D name no standard category of this classification, although parasitism and predation are both real relationships within an ecosystem. The two food chains do not run separately: they are linked, because the waste of the grazing chain becomes the starting material of the detritus chain.
Read the full article: Ecosystem and Food Chains: Components, Levels and Pyramids
Practice Questions
View allThe term ecosystem was coined by which scientist?
- A.A. G. Tansley
- B.Charles Darwin
- C.Raymond Lindeman
- D.Charles Elton
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The British botanist Arthur George Tansley used the word ecosystem in 1935 for a unit in which living organisms and their non-living surroundings are treated together as one system exchanging energy and matter.
Read the full explanation →In a food chain, green plants are called
- A.Producers
- B.Primary consumers
- C.Decomposers
- D.Secondary consumers
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Green plants make their own food from carbon dioxide and water by photosynthesis, using the energy of sunlight, so they are also called autotrophs.
Read the full explanation →The ten per cent law of energy transfer in a food chain was given by
- A.A. G. Tansley
- B.Raymond Lindeman
- C.Odum
- D.Ernst Haeckel
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It says that only about ten per cent of the energy present at one trophic level is passed on to the next, since the rest is used in respiration and other life processes and is lost to the surroundings as heat.
Read the full explanation →Which of the following ecological pyramids is always upright?
- A.Pyramid of numbers
- B.Pyramid of biomass
- C.Pyramid of energy
- D.All three are always upright
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Energy is lost as heat at every transfer from one trophic level to the next, so a higher level can never hold more energy than the level below it.
Read the full explanation →Bacteria and fungi that break down dead plants and animals are known as
- A.Producers
- B.Decomposers
- C.Herbivores
- D.Omnivores
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They feed on dead bodies, fallen leaves and waste matter, break the complex organic substances into simple ones and release nutrients back into the soil, water and air, where plants can take them up again.
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