Q: Which equation correctly represents population density?

$$\text{Population Density} = \frac{\text{Number of Individuals}}{\text{Land Area}}$$

Question 1

Which of the following best describes the difference between a community and an ecosystem?

Accepted Answer

A community is all the populations of different species living and interacting in an area, while an ecosystem includes those populations plus the nonliving environment.

Question 2

Which of the following is an example of an abiotic factor influencing where a species can live?

Accepted Answer

The range of temperatures a species can tolerate

Question 3

A population of fish in a lake is being studied. Over one year, there are 200 births, 50 deaths, 30 immigrations, and 20 emigrations. What is the net change in population size?

Accepted Answer

$$200 + 30 - 50 - 20 = 160$$

Question 4

Which of the following best explains why energy is lost between trophic levels in an ecosystem?

Accepted Answer

Most energy is used for respiration, movement, and lost as heat, so only about 10% is transferred to the next level.

Question 5

Which of the following scenarios is an example of mutualism?

Accepted Answer

Bees pollinating flowers while collecting nectar

Question 6

A population of rabbits is experiencing exponential growth. Which of the following conditions must be true?

Accepted Answer

Resources are unlimited and $$r is $$positive and constant.

Question 7

Which of the following best describes the concept of carrying capacity ($$K$$)?

Accepted Answer

The maximum number of individuals that can be supported indefinitely by the resources in an environment.

Question 8

Which of the following is a real-world example of a trophic cascade?

Accepted Answer

Sea otters control sea urchin populations, allowing kelp forests to thrive.

Question 9

Which equation correctly represents population density?

Accepted Answer

$$	ext{Population Density} = \frac{	ext{Number of Individuals}}{	ext{Land Area}}$$

Question 10

Which of the following is a likely consequence of excess nitrogen runoff into aquatic ecosystems?

Accepted Answer

Eutrophication leading to oxygen depletion and dead zones

Question 11

Which of the following best explains why islands typically have fewer species than equivalent mainland areas?

Accepted Answer

Species on islands are isolated, leading to fewer species due to limited immigration and higher extinction rates.

Question 12

Which of the following is an example of a keystone species and its ecological effect?

Accepted Answer

Sea otters, because their predation on sea urchins maintains kelp forest ecosystems.

Question 13

Which of the following best describes the greenhouse effect?

Accepted Answer

The trapping of heat by atmospheric gases such as carbon dioxide and methane, keeping Earth warm enough for life.

Question 14

Which of the following is a direct effect of ocean acidification on coral reefs?

Accepted Answer

Reduced seawater pH and decreased carbonate ion availability, making it harder for corals to build skeletons

Question 15

A scientist is studying a population using the mark and recapture method. She marks 100 animals, releases them, and later captures 80 animals, 20 of which are marked. What is the estimated population size ($$N$$)? (Use the Lincoln-Petersen estimator: $$N = \frac{n_1$ 	imes n_2$}{m_2$}$$, where $$n_1 = $$number marked initially, $$n_2 = $$number captured the second time, $$m_2 = $$number of marked recaptures.)

Accepted Answer

$$N = \frac{100 	imes 80}{20} = 400$$

Question 16

Which of the following best describes the difference between a fundamental niche and a realized niche?

Accepted Answer

A fundamental niche is the full range of conditions a species could use without competition, while a realized niche is the range it actually uses due to competition and other limits.

Question 17

Which of the following is a direct consequence of the species-area relationship for conservation biology?

Accepted Answer

Larger protected areas support more species, so conserving large habitats is important for biodiversity.

Question 18

Which of the following is an example of a density-dependent factor regulating population growth?

Accepted Answer

A disease spreading more rapidly as population density increases

Question 19

Which of the following best explains why eating higher up on the food chain (e.g., eating meat) requires more land than eating lower (e.g., eating plants)?

Accepted Answer

Energy is lost at each trophic level, so more land is needed to support the same amount of food for higher-level consumers.

Question 20

Which of the following is a likely effect of global warming on ecosystems?

Accepted Answer

Mass biodiversity loss, habitat destruction, and shifting species distributions

Comprehensive Study Guide: Final Exam Review for College Biology (Ecology, Populations, Communities, Conservation)

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