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
Correct answer
Explanation
The correct answer is C, the pyramid of energy. 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. For that reason the energy pyramid is upright in every ecosystem without exception.
Option A, the pyramid of numbers, is inverted in a single tree ecosystem, where one large tree supports thousands of insects and those insects support many birds. Option B, the pyramid of biomass, is inverted in a pond or in the sea, because the phytoplankton present at any moment weigh far less than the fish they support, though they multiply fast enough to feed them. Option D is therefore wrong. This is the most frequently asked point in the chapter.
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 →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.
Read the full explanation →The flow of energy in an ecosystem is
- A.unidirectional
- B.cyclic, like the flow of nutrients
- C.from consumers to producers
- D.unchanged at every trophic level
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Energy enters an ecosystem as sunlight, is fixed by green plants, and then moves from producers to herbivores, to carnivores and finally to decomposers.
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