Question 1

Which of the following best describes the relationship between the snake and the frog in the first image provided?

Accepted Answer

Predation

Question 2

In the context of community ecology, what is a keystone species, and why is its removal often detrimental to an ecosystem?

Accepted Answer

A species that has a disproportionately large impact on community structure; its removal can cause the collapse of the ecosystem.

Question 3

Which of the following equations correctly represents the energy transfer efficiency between trophic levels, if only 10% of energy is transferred to the next level?

Accepted Answer

$$E_{n+1} = 0.1 	imes E_n$$

Question 4

A bee pollinating a flower is an example of which type of interaction?

Accepted Answer

Mutualism

Question 5

Why is it energetically wasteful to eat meat compared to eating plants, according to the 10% rule of energy transfer?

Accepted Answer

Because only about 10% of the energy from plants is transferred to the animals that eat them, so eating meat means consuming energy that has already been lost at lower trophic levels.

Question 6

Which of the following is an example of resource partitioning?

Accepted Answer

Two bird species feeding on the same tree but at different heights to reduce competition.

Question 7

Which of the following best explains why invasive species often become problematic in new environments?

Accepted Answer

They often lack natural predators or competitors in the new environment, allowing their populations to grow unchecked.

Question 8

Which of the following is a correct description of the nitrogen cycle?

Accepted Answer

Nitrogen is fixed from the atmosphere by bacteria and assimilated by plants; humans alter the cycle through fertilizer use.

Question 9

Which of the following is a likely consequence of eutrophication in aquatic ecosystems?

Accepted Answer

Decreased oxygen levels due to microbial activity, leading to dead zones and reduced species diversity.

Question 10

Which of the following best describes commensalism?

Accepted Answer

One species benefits while the other is unaffected.

Question 11

Why is the extinction of a keystone species, such as the sea otter, particularly detrimental to its ecosystem?

Accepted Answer

Because keystone species have a disproportionately large effect on the structure and diversity of their ecosystem; their loss can lead to ecosystem collapse.

Question 12

Which of the following is an example of a behavioral defense against predation?

Accepted Answer

A lizard squirting blood from its eyes

Question 13

Which of the following best explains why predators do not drive their prey to extinction?

Accepted Answer

Prey species often evolve defenses, and predators rely on the continued existence of prey for survival, leading to a balance.

Question 14

Which of the following is a correct statement about the phosphorus cycle?

Accepted Answer

It is a local cycle with rocks as the main abiotic reservoir.

Question 15

Which of the following is a likely reason why average rainfall is higher on the western side of the Sierra Nevada mountains compared to the eastern side?

Accepted Answer

Ocean air rises and cools as it hits the mountains, causing precipitation on the western side and dry conditions on the eastern side.

Question 16

Which of the following best describes the effect of invasive species on native communities?

Accepted Answer

They often outcompete native species, leading to reduced biodiversity and ecosystem disruption.

Question 17

Which of the following is an example of top-down control in an ecosystem?

Accepted Answer

Predators regulate the population sizes of herbivores, which in turn affects plant populations.

Question 18

Which of the following is a correct sequence of energy flow in a terrestrial food web?

Accepted Answer

Sun → Producer → Primary Consumer → Secondary Consumer → Decomposer

Question 19

Which of the following best describes the role of an indicator species in an ecosystem?

Accepted Answer

A species whose presence, absence, or abundance reflects a specific environmental condition.

Question 20

Which of the following is a real-world example of mutualism?

Accepted Answer

A bee pollinating a flower

Communities and Ecosystems: Interactions, Health, and Energy Flow

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