Question 1

Which statement best describes the flow of energy in an ecosystem, as illustrated by the diagrams provided?

Accepted Answer

Energy flows in one direction, from the sun to producers and then through various consumer levels, with heat lost at each step.

Question 2

According to the second law of thermodynamics, what happens to energy as it moves through trophic levels in an ecosystem?

Accepted Answer

Energy is lost as heat at each transfer, increasing entropy.

Question 3

Which group of organisms, shown in the images, plays a critical role in chemical cycling by breaking down nonliving organic matter?

Accepted Answer

Decomposers (such as the mushrooms in the second image)

Question 4

What is the main reason why only about 10% of the energy at one trophic level is available to the next level?

Accepted Answer

Most energy is used for metabolism and lost as heat, as shown by the blue arrows in the first diagram.

Question 5

Which of the following equations correctly represents Net Primary Productivity (NPP)?

Accepted Answer

$$NPP = GPP - R$$

Question 6

A lake receives a large input of nitrogen and phosphorus from agricultural runoff, resulting in the 'after' image (green water). What process is occurring?

Accepted Answer

Eutrophication, leading to algal blooms and potential dead zones.

Question 7

Which factor most strongly limits primary production in the open ocean, as shown in the global NPP map and study materials?

Accepted Answer

Availability of inorganic nutrients such as nitrogen, phosphorus, and iron

Question 8

Why do some aquatic ecosystems, such as the English Channel, have a higher biomass of primary consumers than primary producers?

Accepted Answer

Primary producers (phytoplankton) are consumed rapidly, so their standing biomass is low even though their productivity is high.

Question 9

Which process in the carbon cycle removes carbon dioxide from the atmosphere?

Accepted Answer

Photosynthesis

Question 10

What is the primary biological importance of the nitrogen cycle?

Accepted Answer

It supplies nitrogen for amino acids, proteins, and nucleic acids.

Question 11

A forest is clear-cut, and the outflow of water and minerals from the watershed increases dramatically. What is the most likely explanation?

Accepted Answer

The removal of plants reduces nutrient uptake and retention, increasing nutrient loss.

Question 12

Which restoration ecology technique involves adding organisms to detoxify polluted ecosystems?

Accepted Answer

Bioremediation

Question 13

Which adaptation helps plants access limiting nutrients in terrestrial ecosystems?

Accepted Answer

Mutualisms with nitrogen-fixing bacteria

Question 14

If an ecosystem's Net Ecosystem Production (NEP) is less than zero, what does this indicate?

Accepted Answer

The ecosystem is losing more carbon than it gains and is a carbon source.

Question 15

Which of the following best explains why decomposition rates are faster in warmer ecosystems, as shown in the decomposition graph?

Accepted Answer

Higher temperatures increase the metabolic rates of decomposers, speeding up the breakdown of organic matter.

Question 16

Which of the following is a real-world consequence of increased atmospheric CO2, as described in the study materials?

Accepted Answer

Ocean acidification, which reduces the availability of calcium carbonate for marine organisms.

Question 17

Which process in the phosphorus cycle makes phosphorus available to plants?

Accepted Answer

Weathering of rocks

Question 18

A restoration ecologist wants to increase nitrogen availability in a degraded soil. Which strategy would be most effective?

Accepted Answer

Planting nitrogen-fixing species such as lupins

Question 19

Which law states that matter cannot be created or destroyed, only recycled within ecosystems?

Accepted Answer

Law of Conservation of Mass

Question 20

Which of the following best describes the difference between bioremediation and biological augmentation in restoration ecology?

Accepted Answer

Bioremediation removes harmful substances, while biological augmentation adds essential materials to ecosystems.

Ecosystems and Energy: Energy Flow, Chemical Cycling, and Productivity

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