Free Ecology Ecosystem Energy Flow Questions and Answers

Question 1

In a terrestrial ecosystem, if the primary producers generate 10,000 kcal/m²/year of energy, approximately how much energy would be available to the tertiary consumers?

Accepted Answer

10 kcal/m²/year

Answer

The 10% rule of energy transfer states that only about 10% of the energy from one trophic level is transferred to the next. Primary producers (10,000 kcal) are eaten by primary consumers (10% of 10,000 = 1,000 kcal). Primary consumers are eaten by secondary consumers (10% of 1,000 = 100 kcal). Secondary consumers are eaten by tertiary consumers (10% of 100 = 10 kcal).

Question 2

Which of the following best defines Net Primary Production (NPP)?

Accepted Answer

The rate of energy stored as biomass by producers and made available to consumers.

Answer

Net Primary Production (NPP) is the Gross Primary Production (GPP) minus the energy lost by producers for their own respiration (R). Therefore, NPP represents the energy stored as new biomass that is available to the next trophic level.

Question 3

The pyramid of energy in an ecosystem is always upright and can never be inverted. What is the fundamental reason for this?

Accepted Answer

Energy is lost as heat at each successive trophic level according to the laws of thermodynamics.

Answer

The pyramid of energy is always upright because energy transfer between trophic levels is inefficient. A significant amount of energy is lost as heat during metabolic processes at each level, as described by the Second Law of Thermodynamics. This means that the total energy available at a higher trophic level is always less than the total energy at the level below it.

Question 4

In a deep-sea hydrothermal vent ecosystem, which type of organism forms the base of the food web by harnessing chemical energy?

Accepted Answer

Chemoautotrophic bacteria

Answer

In deep-sea hydrothermal vents, there is no sunlight for photosynthesis. Instead, chemoautotrophic bacteria form the base of the food web. They derive energy from the oxidation of inorganic compounds, such as hydrogen sulfide, released from the vents to produce organic matter.

Question 5

A lake is contaminated with a persistent, fat-soluble pesticide. Which of the following organisms would likely have the HIGHEST concentration of this pesticide in its tissues?

Accepted Answer

A large predatory fish that eats other fish

Answer

This scenario describes biomagnification, where the concentration of a toxin increases at successively higher levels in a food chain. The pesticide accumulates in the fatty tissues of organisms at each trophic level. The large predatory fish, being at the top of this food chain, consumes many smaller fish, each containing the pesticide, leading to the highest concentration in its own body.

Ecology Practice Test

Ecology Practice Test

Free Ecology Ecosystem Energy Flow Questions and Answers