Question

Trophic Levels In an ecosystem, energy is transferred between trophic levels when an organism consumes another organism. A trophic level describes how many consumption steps an organism is away from the original energy source of the Sun. An energy pyramid describes the transfer of energy from one trophic level to another. A primary producer is on the lowest level of an energy pyramid because it is only one consumption step away from the Sun, while a quaternary consumer is on the top of an energy pyramid because it has the most consumption steps between it and the Sun.
Most of the energy for life on Earth comes from the Sun through the processes of photosynthesis and cellular respiration. While matter and energy are conserved, & not all energy and matter are efficiently transferred between trophic levels. Matter is rearranged through chemical reactions to form new molecules. When an organism consumes matter, some of the molecules are stored in the organism as biomass, some matter reacts to release energy, and some matter is discarded. The biomass stored in each trophic level of an energy period contains energy that can be measured in kilocalories. The energy that is not released or discarded is transferred between trophic levels.

Which two statements explain why energy transfer between trophic levels is inefficient?

A.
Some molecules in organisms' bodies are not digestible.

B.
All of the organisms on each trophic level are consumed.

C.
Chemical elements are recombined to form different products.

D.
Primary producers have the most energy in an energy pyramid.

E.
Some of the energy is used by organisms for cellular respiration.

Answer 1

A and E.

A — indigestible parts pass through as waste and aren't transferred as usable energy.
E — organisms use energy for cellular respiration (maintenance, movement, heat), so less energy is available to the next trophic level.