Energy pyramids review

Why would an ecosystem with 100 lions and 10 zebras be unstable?

• The zebras won't have enough food

• The lions won't have enough food

• The lions will have too many opportunities to raise their young

• The lions will pollute the area

Lions need to eat more than one zebra (and humans need to eat more than one apple in a day) because they need more calories than they can get from just one organism.

Why would a heterotroph need to eat more than one organism from the trophic level below it?

• Heterotrophs need carbon dioxide to perform photosynthesis

• Prey species are toxic in large quantities

• It won't get enough nutrition unless it eats enough food

• Animals can never reproduce unless they eat autotrophs

The apple tree used most of its energy making bark, leaves, pollen, enzymes, etc.  We represent this as “energy loss.” When an energy pyramid says 90% of the energy is lost, where is it going?

• Energy is used for movement, only

• Energy is lost from large carnivores and is returned to decomposers

• Energy returns to the Sun

• Energy is used to keep the organism alive and is lost as heat

Most of the energy in the trophic level below is NOT available to the organisms that eat them. Therefore, the ecosystem can only support the number of organisms that can have enough to eat.

Why can the ecosystem only support small numbers of consumers compared to a large number of producers?

• There is not enough energy available to support more consumers

• There is too much energy available to the consumers

• There is not enough food available for decomposers

• There is not enough sunlight available to support more consumers

Scientists call the number of individuals that can be supported the carrying capacity.

In general, the carrying capacity for carnivores is less than the carrying capacity for herbivores, which is less than the carrying capacity for producers

Which level in the energy pyramid represents autotrophs?

• The autotrophs are at level C because they eat herbivores

• The bottom because autotrophs have the most energy and highest biomass

• Autotrophs are at the top (A) because they are important to the ecosystem

• Autotrophs are not pictured in this ecosystem

What would happen to the carrying capacity for a species if the place where it hides from predators was destroyed?

• The carrying capacity would increase

• The carrying capacity would stay the same

• The carrying capacity would decrease

What is carrying capacity?

• How many members of a species can survive in an ecosystem in a stable way

• How many total species live in an ecosystem

• The record number of organisms that ever lived in an area

Which dashed line shows the carrying capacity for a population?

• 1 because the carrying capacity is higher than the number of individuals that ever lived there

• 2 because the carrying capacity is the number of organisms that can live there sustainably

• 3 because the carrying capacity is lower than the number of individuals that ever lived there

• 4 because an ecosystem is only stable when one species is nearly extinct