Question 1

Which of the following best describes 'species evenness' in a biological community?

Accepted Answer

The relative abundance of individuals among the different species in a community.

Question 2

Why is species evenness important for biodiversity in a community?

Accepted Answer

It contributes to ecosystem stability by preventing dominance by a single species.

Question 3

A scientist compares two forest communities. Community A has 10 species, each with roughly equal numbers of individuals. Community B has 10 species, but one species makes up 90% of the individuals. Which community has higher species evenness?

Accepted Answer

Community A, because individuals are distributed more equally among species.

Question 4

Which scenario best illustrates the concept of competitive exclusion?

Accepted Answer

Two species of bacteria compete for the same sugar source, and one species eventually disappears from the environment.

Question 5

Which equation represents the Shannon diversity index, a metric that incorporates both species richness and evenness?

Accepted Answer

$$H' = - \sum_{i=1}^{S} p_i \log p_i$$

Question 6

In a grassland ecosystem, cattle egrets follow cattle and eat insects stirred up by their movement. What type of species interaction is this?

Accepted Answer

Commensalism (+/0)

Question 7

Which of the following is an example of resource partitioning?

Accepted Answer

Two species of warblers feed on insects in different parts of the same tree.

Question 8

What is the difference between a fundamental niche and a realized niche?

Accepted Answer

A fundamental niche is the full range of environmental conditions a species can tolerate, while a realized niche is the portion actually occupied due to competition and other biotic interactions.

Question 9

Which of the following best describes a keystone species?

Accepted Answer

A species whose impact on its community is disproportionately large relative to its abundance.

Question 10

A sea otter population is removed from a kelp forest ecosystem, resulting in an increase in sea urchin numbers and a decline in kelp. What ecological phenomenon does this illustrate?

Accepted Answer

Trophic cascade

Question 11

Which of the following is most likely to increase both the resistance and resilience of a biological community to disturbance?

Accepted Answer

High species richness

Question 12

After a volcanic eruption removes all soil and organisms from an area, what type of succession will occur?

Accepted Answer

Primary succession

Question 13

Which trait is most likely to be found in pioneering species during early succession?

Accepted Answer

High dispersal capability and rapid growth

Question 14

Which of the following is an example of character displacement?

Accepted Answer

Two finch species on the same island evolve different beak sizes to exploit different seed types.

Question 15

Which of the following equations best represents the relationship between population growth and density-dependent competition?

Accepted Answer

$$\frac{dN}{dt} = rN \left(1 - \frac{N}{K}\right)$$

Question 16

Which of the following is NOT a possible outcome of species interactions during succession?

Accepted Answer

Competitive exclusion always occurs

Question 17

In a food web, what is the primary difference between bottom-up and top-down control?

Accepted Answer

Bottom-up control is determined by abiotic factors affecting producers, while top-down control is determined by consumers limiting lower trophic levels.

Question 18

Which of the following best describes mutualism?

Accepted Answer

An interaction where both species benefit (+/+)

Question 19

Which of the following would most likely introduce bias in estimates of species richness in a community?

Accepted Answer

Sampling only large, mobile species and ignoring small, cryptic species.

Community Ecology: Structure, Interactions, and Dynamics

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