Food Webs & Interdependence

Question 1

A meadow food chain contains 1000 g of plant biomass, 100 g of herbivore biomass, and 10 g of carnivore biomass. Which explanation best describes why the total biomass becomes smaller at each higher trophic level?

Accepted Answer

Only about 10 % of the energy captured by the plants is transferred to the herbivores; the remaining energy is lost as heat, movement, and waste, so each higher level receives much less energy.

Answer

Plants use all the sunlight they receive, leaving none for the animals that eat them.

Answer

The number of individuals decreases at higher levels, so the total biomass must also decrease.

Answer

Most of the energy is stored as fat in the herbivores, so less energy is available for the carnivores.

Question 2

The table below shows the amount of algae (a food resource) in a pond and the corresponding number of fish observed. Algae (grams) | Fish population 10 | 20 20 | 35 30 | 45 40 | 55 Which statement is best supported by these data?

Accepted Answer

When the amount of algae in the pond increases, the fish population tends to increase.

Answer

When the amount of algae in the pond increases, the fish population tends to decrease.

Answer

There is no clear relationship between algae amount and fish population.

Answer

The fish population stays the same regardless of the amount of algae.

Question 3

A researcher introduces the same species of herbivorous beetle into two ecosystems. In the forest ecosystem the beetle’s preferred plant is plentiful, while in the grassland ecosystem that same plant is scarce. A native carnivorous spider preys on the beetle in both ecosystems. Which statement best predicts the relative change in the spider’s population in the two ecosystems?

Accepted Answer

The spider population will increase more in the forest than in the grassland.

Answer

The spider population will increase more in the grassland than in the forest.

Answer

The spider population will decrease in both the forest and the grassland.

Answer

The spider population will increase by the same amount in both ecosystems.

Try three questions

A meadow food chain contains 1000 g of plant biomass, 100 g of herbivore biomass, and 10 g of carnivore biomass. Which explanation best describes why the total biomass becomes smaller at each higher trophic level?

The table below shows the amount of algae (a food resource) in a pond and the corresponding number of fish observed. Algae (grams) | Fish population 10 | 20 20 | 35 30 | 45 40 | 55 Which statement is best supported by these data?

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