What is an energy pyramid and what does it illustrate?

What is an energy pyramid and what does it illustrate?

• A. A diagram showing energy or biomass at each trophic level; it illustrates decreasing energy available at higher levels.
• B. A map of species distribution in space.
• C. A chart of rainfall over time.
• D. A model of genetic variation.

Answer: (A)

An energy pyramid is a diagram that shows how much energy or biomass is available at each trophic level in an ecosystem, and it demonstrates that energy becomes scarcer as you move to higher levels. This happens because energy transfer between levels is not efficient: producers capture energy from the sun, herbivores and later carnivores consume it, but much of that energy is lost as heat, used for daily activities, or exits as waste. Because only a fraction is passed on, each successive level has less energy to support organisms, so there are fewer organisms or less biomass higher up. Some pyramids reflect the amount of energy available, while others show biomass. This concept helps explain why ecosystems have a limited number of high-level predators and why the base of the food chain needs to be large to support the rest of the web. These other choices describe different ideas: a map of where species live, a chart of rainfall over time, or a model of genetic variation.

An energy pyramid is a diagram that shows how much energy or biomass is available at each trophic level in an ecosystem, and it demonstrates that energy becomes scarcer as you move to higher levels. This happens because energy transfer between levels is not efficient: producers capture energy from the sun, herbivores and later carnivores consume it, but much of that energy is lost as heat, used for daily activities, or exits as waste. Because only a fraction is passed on, each successive level has less energy to support organisms, so there are fewer organisms or less biomass higher up. Some pyramids reflect the amount of energy available, while others show biomass. This concept helps explain why ecosystems have a limited number of high-level predators and why the base of the food chain needs to be large to support the rest of the web.

These other choices describe different ideas: a map of where species live, a chart of rainfall over time, or a model of genetic variation.