Question 1

What is the direction of energy flow in an ecosystem?

Accepted Answer

Energy flows unidirectionally from sunlight to producers and then to consumers. Unlike nutrients, energy is not recycled within the ecosystem.

Question 2

What are the three ecological pyramids?

Accepted Answer

The three ecological pyramids are the pyramid of number, the pyramid of biomass and the pyramid of energy. Each pyramid represents a different quantity at successive ecosystem levels.

Question 3

Why is the pyramid of energy always upright?

Accepted Answer

Only part of the energy available at one level becomes available to the next level, while the rest is not transferred to the higher consumer level. As a result, available energy decreases upward, keeping the energy pyramid upright.

Question 4

Why can the pyramid of number invert in a tree ecosystem?

Accepted Answer

A single tree can support many herbivores, such as insects and other plant-eating animals. Therefore, the number of producers can be lower than the number of primary consumers, producing an inverted number pyramid.

Question 5

Why can the pyramid of biomass invert in an aquatic ecosystem?

Accepted Answer

Phytoplankton have a very rapid turnover, so their standing biomass at one moment can remain small. The standing biomass of consumers such as fish can therefore be greater, producing an inverted biomass pyramid.

Ecosystem Energy Flow and Ecological Pyramids Lab

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Practice