Video Transcript
The diagram shows an energy pyramid in a woodland ecosystem. How is the energy transferred throughout the pyramid? (A) From plants to herbivores only. (B) From carnivores to plants indirectly. (C) From plants to carnivores indirectly. Or (D) from herbivores to omnivores only.
To answer this question, let’s see how energy is transferred through the various
levels shown in this energy pyramid, starting at its base, and define some key terms
along the way.
The energy that is first made available to most ecosystems is provided in the form of
light energy, usually from the Sun. Producers like plants are able to capture light energy and convert it into chemical
energy in the form of organic compounds through photosynthesis. These organic compounds then allow the energy stored within them to be transferred to
other organisms that eat the plants. Organisms that exclusively eat plant matter are called herbivores.
Omnivores also eat plant matter. They may consume animal matter too, such as the herbivores at the level below them in
this pyramid. And thus the energy is transferred to the omnivores via organic compounds the
herbivores obtain from plant matter and incorporate into their body mass. Knowing this, we can eliminate answer option (A), as energy will also be transferred
from plants to omnivores and from herbivores to omnivores, not just from plants to
herbivores.
Carnivores are organisms that consume animal matter only, obtaining all of their
energy from organic compounds in other animals. Some carnivores may consume herbivores, some may consume omnivores, and some may
consume both. Either way, the organic matter and energy stored within it that was originally
produced by the plants is transferred indirectly to the carnivores via other
animals. This suggests that the correct answer is option (C), but let’s check the remaining
options to be sure.
Option (B) says that energy is transferred from carnivores to plants indirectly. This is incorrect, as energy is transferred from plants to herbivores, omnivores, and
carnivores, not the other way around.
Option (D) states that energy is transferred from herbivores to omnivores only. This is also wrong, as we know that energy is also transferred from herbivores to
omnivores and from plants to omnivores. So we can confirm that the correct option describing how energy is transferred in
this pyramid is (C), from plants to carnivores indirectly.
