$$\text{NPP} = \text{GPP} - \text{Respiration}$$

Question 1

Which of the following best explains why energy is lost as it moves through trophic levels in an ecosystem?

Accepted Answer

Energy is lost as heat due to metabolic processes at each trophic level.

Question 2

A pyramid of energy in an ecosystem typically shows:

Accepted Answer

Energy decreases as you move up each trophic level.

Question 3

Which of the following is the correct formula for net primary productivity (NPP)?

Accepted Answer

$$	ext{NPP} = 	ext{GPP} - 	ext{Respiration}$$

Question 4

Which factor most commonly limits primary production in terrestrial ecosystems?

Accepted Answer

Annual precipitation and temperature

Question 5

In aquatic ecosystems, primary production is most often limited by:

Accepted Answer

Light and nutrient availability

Question 6

Which process is responsible for converting atmospheric nitrogen ($$N_2) $$into a form usable by plants?

Accepted Answer

Nitrogen fixation by bacteria

Question 7

What is biomagnification, and why is it a concern in food webs?

Accepted Answer

It is the accumulation of non-biodegradable chemicals in organisms, increasing in concentration at higher trophic levels.

Question 8

Which of the following best describes the role of decomposers in an ecosystem?

Accepted Answer

They recycle nutrients by breaking down dead organic matter.

Question 9

A carnivorous plant, such as a sundew, may be considered both a ________ when it eats a carnivorous spider.

Accepted Answer

Producer and a secondary consumer

Question 10

Why are food chains in most ecosystems limited to 5-6 trophic levels?

Accepted Answer

Energy is lost with each trophic level, eventually not enough remains to support another level.

Question 11

Which of the following is an example of a real-world consequence of eutrophication in freshwater ecosystems?

Accepted Answer

Overgrowth of algae leading to oxygen depletion and fish kills

Question 12

Which of the following best describes the water cycle?

Accepted Answer

It is a physical process involving evaporation and precipitation.

Question 13

Deforestation can strongly affect the water cycle by:

Accepted Answer

Leading to desertification, soil erosion, and altered water runoff patterns

Question 14

Which of the following equations correctly represents photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O + 	ext{energy} ightarrow C_6H_{12}O_6$ + 6O_2$$

Question 15

Which of the following is a limiting nutrient in most freshwater ecosystems, and what is a consequence of its excess?

Accepted Answer

Phosphorus; eutrophication

Question 16

Which of the following statements about the carbon cycle is correct?

Accepted Answer

Carbon cycles among biological, geological, and atmospheric pools.

Question 17

Which of the following best describes secondary production in an ecosystem?

Accepted Answer

The gain in biomass of heterotrophs and decomposers, limited by primary production and transfer efficiency.

Question 18

Which of the following is a direct effect of increased atmospheric $$CO_2 on $$the oceans?

Accepted Answer

Increased $$CO_2$$ dissolved in ocean water

Question 19

Which of the following mechanisms is NOT a way nutrients move between pools in an ecosystem?

Accepted Answer

Photosynthesis converting minerals into energy

Question 20

Farmers often add ammonia-based fertilizers to their fields because:

Accepted Answer

Atmospheric nitrogen ($$N_2) is $$abundant but not directly usable by most plants.

Ecosystem Ecology: Energy Flow, Nutrient Cycling, and Productivity

Study Guide - Practice Questions