CLEP Biology Ecosystems and Energy Flow 3

Question 1

If a grassland ecosystem has 10,000 kcal available at the producer level, approximately how many kcal are available to secondary consumers, assuming 10% efficiency at each transfer?

Accepted Answer

100 kcal

Answer

At 10% efficiency, 10,000 kcal → 1,000 kcal (primary consumers) → 100 kcal (secondary consumers).

Question 2

Mutualistic mycorrhizal fungi associated with plant roots primarily benefit the plant by:

Accepted Answer

Increasing the plant's ability to absorb water and phosphorus

Answer

Mycorrhizal fungi greatly extend the root surface area, enhancing uptake of water and minerals, especially phosphorus, in exchange for plant carbohydrates.

Question 3

Which of the following best illustrates a bottom-up trophic cascade?

Accepted Answer

Fertilizer runoff increases algae growth, which supports more fish

Answer

A bottom-up cascade starts at the producer level; nutrient addition boosts primary producers, increasing biomass at each successive trophic level.

Question 4

In the phosphorus cycle, which reservoir contains the largest amount of phosphorus on Earth?

Accepted Answer

Rocks and sediments

Answer

Most of Earth's phosphorus is locked in rocks and marine sediments, making it unavailable until released by weathering over geological timescales.

Question 5

An ecological pyramid of numbers can be inverted (wider at the top) when:

Accepted Answer

Parasites are counted and each host supports many parasites

Answer

A single large host organism can harbor thousands of parasites, so an inverted numbers pyramid occurs when parasites constitute the highest trophic level.

CLEP Practice Test

CLEP Practice Test

CLEP Biology Ecosystems and Energy Flow 3