Why is 10% energy transferred to the next trophic level?

Food chains and webs show the transfer of energy between trophic levels. They can be represented as pyramids of number and biomass and the efficiency of these transfers can be calculated.

Answer

Hint: When organic molecules from the body of an organism are eaten by another organism, energy can move from one trophic level to the next. However, it is not typically very effective to transfer energy between trophic stages.

Complete answer:

So, the correct answer is ‘Chemical energy’.

Note: -Net efficiency of production (NPE) determines how effectively each trophic level utilizes and transforms the energy from its food into biomass to fuel the next trophic level.

The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat. If a grassland ecosystem has 10,000 kilocalories (kcal) of energy concentrated in vegetation, only about 1,000 kcal will be transferred to primary consumers, and very little (only 10 kcal) will make it to the tertiary level. Energy pyramids such as this help to explain the trophic structure of an ecosystem: the number of consumer trophic levels that can be supported is dependent on the size and energy richness of the producer level.

© Encyclopædia Britannica, Inc.

Living things need energy to grow, breathe, reproduce, and move. Energy cannot be created from nothing, so it must be transferred through the ecosystem. The primary source of energy for almost every ecosystem on Earth is the sun. Primary producers use energy from the sun to produce their own food in the form of glucose, and then primary producers are eaten by primary consumers who are in turn eaten by secondary consumers, and so on, so that energy flows from one trophic level, or level of the food chain, to the next. The easiest way to demonstrate this energy flow is with a food chain. Each link in the chain represents a new trophic level, and the arrows show energy being passed along the chain. At the bottom of a food chain is always the primary producer. In terrestrial ecosystems most primary producers are plants, and in marine ecosystems, most primary producers are phytoplankton. Both produce most the nutrients and energy needed to support the rest of the food chain in their respective ecosystems.

All the biomass generated by primary producers is called gross primary productivity. Net primary productivity is what is left over after the primary producer has used the energy it needs for respiration. This is the portion that is available to be consumed by the primary consumers and passed up the food chain. In terrestrial ecosystems, primary productivity is highest in warm, wet places with plenty of sunlight, like tropical forest regions. In contrast, deserts have the lowest primary productivity. In marine ecosystems, primary productivity is highest in shallow, nutrient rich waters, such as coral reefs and algal beds.

To show the flow of energy through ecosystems, food chains are sometimes drawn as energy pyramids. Each step of the pyramid represents a different trophic level, starting with primary producers at the bottom. The width of each step represents the rate of energy flow through each trophic level. The steps get smaller further up the pyramid because some of that energy is changed to a form that cannot be consumed by organism at the next higher step in the food chain. This happens at every step of the pyramid.

Not all of the energy generated or consumed in one trophic level will be available to the organisms in the next higher trophic level. At each level, some of the biomass consumed is excreted as waste, some energy is changed to heat (and therefore unavailable for consumption) during respiration, and some plants and animals die without being eaten (meaning their biomass is not passed on to the next consumer). The waste and dead matter are broken down by decomposers and the nutrients are recycled into the soil to be taken up again by plants, but most of the energy is changed to heat during this process. On average, only about 10 percent of energy stored as biomass in a trophic level is passed from one level to the next. This is known as “the 10 percent rule” and it limits the number of trophic levels an ecosystem can support.

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