Question 1

Describe how chemical nutrients enter and are recycled through an ecosystem.

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Question 2

The amount of energy captured by photosynthetic organisms, minus the amount lost as heat from respiration and other life processes, is called ________.

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Question 3

To best use the Earth's net primary productivity to feed the most people, diets should be modified to include ________, and gathering the maximum amount of energy available from a given biomass of producers.

Accepted Answer

Moving lower down the food chain means consuming a greater amount of plant material directly, rather than indirectly through an animal that has itself consumed many plants. This is the best approach to using the Earth's net primary productivity efficiently, because it allows for the maximum amount of energy to be gathered directly from producers (plants). Consuming only meat, whether moving higher or lower up the food chain, is not sustainable or efficient, because it requires a much greater amount of energy (and therefore resources) to produce the same amount of food.

Question 4

Match each term to its correct description below.
-Found at the poles and on mountaintops, the vegetation of this biome is dominated by low-growing flowering plants, and the rock landscape is covered in mosses and lichens. Rodents provide food for carnivores like foxes and wolves. The few large mammals include bears and musk oxen.

Accepted Answer

The description matches the characteristics of the tundra biome, which is found at the poles and on mountaintops, has low-growing vegetation dominated by flowering plants, and is covered in mosses and lichens. The presence of rodents, carnivores like foxes and wolves, and large mammals like bears and musk oxen also align with the tundra biome.

Question 5

Producers capture energy from the ________ and transform it into fuel energy that passes up the food chain as one organism eats another.

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Question 6

Between late 1997 and mid-2008, satellites observed that warmer-than-average ocean temperatures led to below-average chlorophyll concentrations in the oceans. This finding suggests that continued warming of the Earth's oceans could lead to

Accepted Answer

Chlorophyll is essential for photosynthesis in marine organisms, and a decrease in chlorophyll concentrations would indicate a decrease in primary productivity in the oceans. This would result in the oceans removing less carbon dioxide from the atmosphere, as photosynthesis is a key process in carbon sequestration.

Question 7

Explain why ecosystems do not always have sharply defined physical boundaries.

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Question 8

An ecosystem that experiences a small increase in nutrients available to primary producers is likely to show

Accepted Answer

An increase in nutrients available to primary producers will likely increase their growth and reproduction, resulting in an increase in net primary productivity.

Question 9

Considering this food chain, explain how many calories are available in the consumer trophic levels and why.

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Question 10

Which of the following is NOT an easily testable hypothesis regarding net primary productivity?

Accepted Answer

The tastiness of products of NPP is not a measurable or easily testable hypothesis. The other three hypotheses are easily testable as they involve quantifiable variables.

Question 11

Other than tropical forests, the most productive biomes tend to be

Accepted Answer

Estuaries are highly productive due to the nutrient-rich waters where rivers meet the ocean, creating a diverse and abundant ecosystem for both marine and terrestrial species. Deep oceans have low productivity due to the lack of sunlight and nutrients, deserts have limited plant growth, and tundras have short growing seasons and low plant diversity.

Question 12

On what four factors does net primary productivity rely, and what terrestrial ecosystem is the most productive because of these factors?

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Question 13

In marine ecosystems, net primary productivity tends to be

Accepted Answer

Along shorelines, nutrients from the land (such as runoff from fertilizers or animal waste) can stimulate phytoplankton growth and increase net primary productivity in marine ecosystems. This is known as the "continental shelf pump," where the shallow waters of the continental shelf act as a nutrient trap and support a high level of primary productivity. Therefore, net primary productivity tends to be greater along shorelines where terrestrial nutrients enter the marine environment.

Question 14

The figure below shows the net primary productivity (NPP) in terrestrial biomes around the world. The pattern of NPP in terrestrial ecosystems as shown suggest that

Accepted Answer

The pattern of NPP in terrestrial biomes around the world suggests that productivity is highest at the equator, which is characterized by high temperatures and abundant sunlight. This indicates that terrestrial productivity is highly sensitive to temperature and available sunlight.

Question 15

A group of living communities interacting with one another and their shared physical environment is a(n) ________.

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Question 16

The figure below shows the net primary productivity (NPP) in marine biomes around the world. The pattern of NPP in marine ecosystems as shown suggests that

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Question 17

Each level of an energy pyramid corresponds to a step in a food chain and is called a(n) ________ level.

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Question 18

Why are deserts and tundra among the least productive terrestrial biomes?

Accepted Answer

Water availability and temperature are important limiting factors in net primary productivity (NPP). In both desert and tundra biomes, water is not easily accessible by plants and the extreme temperature conditions further limit productivity.

Question 19

What best explains this observation: consumers directly use approximately 20 percent of a forest's net primary productivity (NPP), whereas decomposers directly use approximately 80 percent?

Accepted Answer

Consumers typically only eat certain parts of organisms (such as leaves, fruits, or muscle tissue), which make up a smaller portion of the organism's overall energy content. In contrast, decomposers break down and use the entire body of dead organisms, which makes up a larger percentage of the overall NPP.

Question 20

Other than the polar tundra, the LEAST productive terrestrial biomes tend to be

Accepted Answer

Deserts receive very little precipitation, and their extreme temperatures and scarce water resources make it difficult for plants and animals to thrive. This results in relatively low productivity compared to other biomes. The other options listed (temperate forests, tropical forests, and estuaries) are generally much more productive in terms of biomass production and biodiversity.

Quiz 18: Ecosystems