Q: Which of the following equations accurately represents the change in population size over time?

$$\Delta N = (\text{Births} + \text{Immigrants}) - (\text{Deaths} + \text{Emigrants})$$

Question 1

Which of the following best describes the difference between biotic and abiotic factors in an ecosystem?

Accepted Answer

Biotic factors are living components such as bacteria and trees, while abiotic factors are non-living components such as rocks and water.

Question 2

A polar bear hunts seals on sea ice in the Arctic. Which term best describes the role the polar bear plays in its ecosystem?

Accepted Answer

Niche

Question 3

Which of the following is NOT a biotic factor?

Accepted Answer

Soil pH

Question 4

Which level of ecological study would focus on how the spatial arrangement of forests and wetlands affects capybara populations?

Accepted Answer

Landscape ecology

Question 5

Which question would a community ecologist most likely investigate?

Accepted Answer

How do interactions between different species influence the structure and dynamics of a forest ecosystem?

Question 6

Which of the following equations accurately represents the change in population size over time?

Accepted Answer

$$\Delta N = (	ext{Births} + 	ext{Immigrants}) - (	ext{Deaths} + 	ext{Emigrants})$$

Question 7

Suppose a population of rabbits in a forest has an initial population of 500. Over the course of one year, 200 new rabbits are born, 150 rabbits die, 20 rabbits emigrate, and 50 rabbits immigrate. What is the population size at the end of the year?

Accepted Answer

580 rabbits

Question 8

Which of the following statements about metapopulations is true?

Accepted Answer

Metapopulations are groups of spatially separated local populations connected by emigration and immigration.

Question 9

Which of the following is an example of semelparity?

Accepted Answer

An agave plant which stores energy throughout life, then releases many seeds before dying.

Question 10

If a cohort of female European Hedgehogs has a starting population of 2,500 and a survivorship of 0.353 after 2 years, how many hedgehogs make it to 2 years old?

Accepted Answer

353

Question 11

A carp has many offspring at once, but the majority of them are eaten by predators in their first year of life. As carp develop & grow, they have fewer predators in later life. Which survivorship curve do carp exhibit?

Accepted Answer

Type III

Question 12

Which of the following is a density-independent factor that limits a population’s growth?

Accepted Answer

Drought

Question 13

A population of 200 fish in an isolated pond experiences a per capita birth rate ($$b) of 0.3 $$and a per capita death rate ($$d) of 0.1 in a $$month. What is the intrinsic rate of increase ($$r) $$for this population?

Accepted Answer

$$r = 0.2$$

Question 14

If a bacterial population starts with 100 cells and has a per capita population growth rate $$r of 0.1 $$cells per hour per cell, what would be the population size after 5 hours?

Accepted Answer

272 individuals

Question 15

A population of spotted hyenas in a South African National Park currently has 87 individuals. The carrying capacity for spotted hyenas in the park is estimated to be 125 hyenas & the intrinsic growth rate ($$r) is 0.25 $$hyenas/year/hyena. What is the instantaneous rate of population growth of the spotted hyena population?

Accepted Answer

15 hyenas/year

Question 16

Which type of survivorship curve would you expect K-selected organisms to follow & why?

Accepted Answer

Type I, because many resources are allocated to the survival of few offspring.

Question 17

Which of the following scenarios is an example of direct, asymmetric competition?

Accepted Answer

Cheetahs struggling to get enough food because a pride of lions are eating all the zebra in the territory.

Question 18

Which of the following statements is true regarding competition between organisms?

Accepted Answer

It decreases the fitness of all organisms involved.

Question 19

Which of the following is an example of a keystone species?

Accepted Answer

A sea star that preys on mussels, preventing them from dominating the intertidal zone.

Ecology and Community Interactions: Foundations of Population and Community Ecology

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