Q: Which of the following equations accurately represents the change in population size ($$\Delta N) $$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, and the melting of sea ice due to climate change affects its hunting success. This scenario illustrates the influence of which ecological factor?

Accepted Answer

Both biotic and abiotic factors

Question 3

Which of the following best defines an organism's niche?

Accepted Answer

The ecological role a species performs in its habitat, including how it utilizes resources and interacts

Question 4

Which scenario best illustrates the concept of a realized niche?

Accepted Answer

A species of barnacle occupies only the lower part of a rock because a stronger competitor excludes it from the upper part.

Question 5

Which of the following equations accurately represents the change in population size ($$\Delta N) $$over time?

Accepted Answer

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

Question 6

A population of rabbits in a meadow starts with 500 individuals. Over one year, 200 rabbits are born, 150 die, 20 emigrate, and 50 immigrate. What is the population size at the end of the year?

Accepted Answer

580 rabbits

Question 7

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

Accepted Answer

Drought

Question 8

A population of 10,000 rabbits experiences 400 births and 150 deaths in a year. What is the per capita population growth rate ($$r$$)?

Accepted Answer

$$r = 0.25$$ rabbits/year/rabbit

Question 9

Which population growth model accounts for environmental limitations and carrying capacity?

Accepted Answer

Logistic model

Question 10

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? Use the exponential growth equation $$N_t = N_0$ e$$^{rt}$$.

Accepted Answer

272 individuals

Question 11

Which of the following statements about r- and K-selection is true?

Accepted Answer

K-selected organisms tend to exhibit iteroparity so they can better care for their offspring.

Question 12

Which of the following 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 13

Which of the following scenarios is most likely to result in competitive exclusion?

Accepted Answer

When there are 2 species with completely overlapping niches in a community.

Question 14

Bats use echolocation to catch prey, and some moths can detect these sounds to avoid predation. This is an example of:

Accepted Answer

Coevolution

Question 15

Which two defense mechanisms are exhibited by poison dart frogs?

Accepted Answer

Aposematic coloration & Müllerian mimicry

Question 16

Certain strains of E. coli bacteria live in human intestines, producing vitamin K for humans while receiving nutrition. This relationship is an example of:

Accepted Answer

Mutualism

Question 17

If a forest contains 47,000 kg of plant material, how many kg of tertiary consumers can it support, assuming a 10% energy transfer between trophic levels?

Accepted Answer

4.7 kg

Question 18

Which of the following could be characterized as top-down control in a community?

Accepted Answer

Otters keeping the sea urchin population down by consuming them.

Question 19

Which of the following statements most accurately describes ecological succession?

Accepted Answer

The species that make up the community gradually change over time as the environment changes.

Ecology and Community Interactions: Foundations, Population, and Community Dynamics

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