The size of a food chain can vary, but the number of levels that a food chain can reach is limited. why does this limit exist? plants are not infinite in number. producers are limited by consumers. carnivores are too large to be eaten. energy is lost at each trophic level.

The correct answer will be D. (Energy is lost at each trophic level)

Explanation:

Food chain is the transfer of energy in the from of food from organism to organism at each trohic level in an ecosystem.

energy flows from at each trophic level when organism of higher level consumes organism of lower level.

Energy move up in order from: Primary producers (1000 kJ)

                                                                ↓

                                                  Primary consumers  (1O0 kJ)

                                                                 ↓

                                                   Secondary consumers (10 kJ)

                                                                ↓  

                                     Tertiary and other high-level consumers (1 kJ)

Energy is passed at each trophic level by 10% Rule proposed by Raymond Lindeman which states that only ten percent of the energy will be passed on at each trophic level due to the following reasons-

1.energy is lost in the form of heat at each step

2.energy is lost  through biological processes such as respiration

3. only consumable energy by organisms is transferred at trophic level.

so, food chain cannot encompass more than 4-5 trophic level.

Thus, option D is correct.

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