$$\text{Energy}_{\text{next level}} = \text{Energy}_{\text{previous level}} \times 0.1$$

Question 1

Which process is primarily responsible for the entry of energy into most terrestrial ecosystems?

Accepted Answer

Photosynthesis

Question 2

What is the key event in photosynthesis that allows for the conversion of inorganic carbon into organic molecules?

Accepted Answer

Carbon fixation

Question 3

Gross Primary Production (GPP) in an ecosystem is best defined as:

Accepted Answer

The total carbon fixed by all autotrophs

Question 4

Which equation correctly relates Net Primary Production (NPP), Gross Primary Production (GPP), and Respiration (R)?

Accepted Answer

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

Question 5

A lake with clear water, low algal growth, and high oxygen content is most likely:

Accepted Answer

Oligotrophic

Question 6

Which nutrient is typically limiting in terrestrial habitats, thus constraining NPP?

Accepted Answer

Nitrogen

Question 7

Eutrophication in aquatic systems is most often caused by an excess of which nutrient?

Accepted Answer

Phosphorous

Question 8

Which of the following is a major anthropogenic source of phosphates contributing to eutrophication?

Accepted Answer

Detergents containing sodium tripolyphosphate (STPP)

Question 9

What is the primary consequence of eutrophication in lakes and coastal waters?

Accepted Answer

Decrease in dissolved oxygen leading to dead zones

Question 10

In the context of trophic levels, which organism would be classified as a primary consumer?

Accepted Answer

Grasshopper

Question 11

Which of the following best describes a detritivore?

Accepted Answer

An organism that feeds on dead and decomposing material

Question 12

Why are food webs considered more realistic representations of ecosystem feeding relationships than food chains?

Accepted Answer

Food webs illustrate the complex, interconnected feeding relationships among organisms

Question 13

If a fertilizer runoff increases the phosphorous concentration in a lake, what is the most likely sequence of ecological events?

Accepted Answer

Increase in algal growth, decrease in oxygen, fish die-off

Question 14

Which of the following equations correctly represents the relationship between energy flow and trophic levels in an ecosystem?

Accepted Answer

$$	ext{Energy}_{	ext{next level}} = 	ext{Energy}_{	ext{previous level}} 	imes 0.1$$

Question 15

Which aquatic ecosystem typically has the highest average net primary productivity?

Accepted Answer

Estuaries

Question 16

A region in the Gulf of Mexico near the Mississippi River Delta is known for its 'dead zone.' What is the primary cause of this phenomenon?

Accepted Answer

Nutrient runoff leading to eutrophication and hypoxia

Question 17

Which of the following would most likely increase the Net Primary Production (NPP) of a terrestrial ecosystem?

Accepted Answer

Addition of nitrogen fertilizer

Question 18

What is the ecological significance of limiting nutrients in an ecosystem?

Accepted Answer

They restrict further growth and constrain NPP

Question 19

Which trophic level is most directly responsible for converting solar energy into chemical energy?

Accepted Answer

Primary producers

Question 20

A government bans phosphates in detergents. What is the most likely long-term ecological effect in local freshwater systems?

Accepted Answer

Decrease in algal blooms and improved water quality

Ecosystem Energy Flow, Nutrient Limitation, and Trophic Interactions

Study Guide - Practice Questions