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MODEL PAPER 3 — BIOLOGY STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceBIOLOGYMODEL PAPER 33 Marks
Question
i. Name an ideal pyramid existing in an ecosystem. Construct it up to its three trophic levels along with their
names.
ii. The sun provides 1,000,000 J of sunlight (solar energy) to an ecosystem. Write the amount of energy that is available to the first and third trophic levels, respectively.
✓

Answer

i. An ideal pyramid existing in an ecosystem is the pyramid of energy. In the ecological pyramid, the first trophic level represents the producers which are the green plants. Primary consumers,which are the herbivores, represent the second trophic level. Secondary consumers represent the third trophic level. 
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ii. Primary producers convert only 1% of the energy in the sunlight available to them. So, if the sun provides 1,000,000 J of solar energy, only 10,000 J is available at the producer or the first trophic level. Now, according to the 10% law of energy transfer, only 10% of energy is transferred from one trophic level to the next higher level. Therefore, the third trophic level will get 100 J of energy.

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