Question 1

Which of the following best describes an ecosystem?

Accepted Answer

A community of living organisms interacting with each other and their physical environment.

Question 2

A keystone species is removed from a community. What is the most likely result?

Accepted Answer

The structure and diversity of the community will change significantly.

Question 3

Which equation best represents the energy transfer between trophic levels in an ecosystem?

Accepted Answer

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

Question 4

Which of the following is an example of mutualism?

Accepted Answer

Bees pollinating flowers while collecting nectar.

Question 5

A population of rabbits in a meadow increases rapidly, then levels off. Which model best describes this growth?

Accepted Answer

Logistic growth

Question 6

Which of the following is a density-dependent limiting factor?

Accepted Answer

A disease spreading through a population

Question 7

Which process is primarily responsible for returning carbon to the atmosphere in the carbon cycle?

Accepted Answer

Respiration

Question 8

If a toxin accumulates in producers at a concentration of 2 ppm, what is the expected concentration in a tertiary consumer, assuming biomagnification and four trophic levels?

Accepted Answer

$$16 	ext{ ppm}$$

Question 9

Which of the following best explains why invasive species often disrupt ecosystems?

Accepted Answer

They have no natural predators in the new environment.

Question 10

A farmer applies fertilizer to a field, which then runs off into a nearby lake. What is the most likely ecological consequence?

Accepted Answer

Eutrophication leading to algal blooms and decreased oxygen levels

Question 11

Which equation represents the logistic growth of a population?

Accepted Answer

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

Question 12

Which of the following is an example of a real-world commensalism interaction?

Accepted Answer

Barnacles attaching to a whale's skin

Question 13

Which of the following best describes primary succession?

Accepted Answer

The colonization of bare rock by lichens and mosses

Question 14

Which of the following is a likely effect of removing all top predators from an ecosystem?

Accepted Answer

Uncontrolled growth of herbivore populations

Question 15

Which of the following is the best example of a density-independent factor affecting a population?

Accepted Answer

Flooding

Question 16

Which of the following best describes the role of decomposers in an ecosystem?

Accepted Answer

They break down dead organic matter, recycling nutrients.

Question 17

Which of the following is a likely outcome of habitat fragmentation?

Accepted Answer

Decreased biodiversity due to isolated populations

Question 18

Which of the following equations best represents the relationship between population size ($$N$$), birth rate ($$b$$), and death rate ($$d) $$over time?

Accepted Answer

$$\frac{dN}{dt} = (b - d)N$$

Question 19

Which of the following is an example of secondary succession?

Accepted Answer

Grasses growing after a forest fire

Question 20

Which of the following best explains why energy transfer between trophic levels is inefficient?

Accepted Answer

Most energy is used for metabolic processes or lost as heat.

Unit 8: Ecology – Interactions and Changes in Communities and Ecosystems

Study Guide - Practice Questions

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