Question 1

Which of the following graphs illustrates the population growth curve of single bacterium growing in a flask of ideal medium at optimum temperature over a 24-hour period?

Accepted Answer

The graph in option C shows the typical sigmoid (S-shaped) curve of bacterial growth. The lag phase (initial slow growth), exponential phase (rapid growth), and stationary phase (population stabilization) are all clearly visible. The decline in population in the death phase is not visible as the time period is limited to 24 hours. The graphs in options A, B, D, and E do not show the typical sigmoid curve of bacterial growth.

Question 2

When climbing a mountain, we can observe transitions in biological communities that are analogous to the changes

Accepted Answer

As you climb a mountain, the temperature, precipitation, and altitude all change, resulting in transitions in vegetation similar to the changes seen in biomes at different latitudes.

Question 3

Use this description to answer the following question.
In areas of permafrost, stands of black spruce are frequently observed in the landscape, whereas other tree species are noticeably absent. Often these stands are referred to as "drunken forests" because many of the black spruce are displaced from their normal vertical alignment.
-What might be the adaptive significance of these unusual forests growing the way they do in this marginal habitat?

Accepted Answer

The permafrost prevents deep root penetration, leading to shallow root systems that cause the trees to tilt.

Question 4

Use the survivorship curves in Figure 40.3 to answer the following questions.
  Figure 40.3
-Which statement best explains survivorship curve B?

Accepted Answer

Survivorship curves depict the number of individuals in a cohort that survive to different ages, and they can only decrease because once an individual dies, it cannot be brought back to life. Thus, a curve showing an increase in survivorship over time, as implied in the question, is not possible in nature.

Question 5

Use the survivorship curves in Figure 40.3 to answer the following questions.
  Figure 40.3
-Which curve best describes survivorship in humans who live in developed nations?

Accepted Answer

The answer of Use the survivorship curves in Figure 40.3...

Question 6

If the direction of Earth's rotation reversed, the most predictable effect would be

Accepted Answer

If the Earth's rotation were to reverse, the most predictable effect would be a change in the direction of prevailing winds, including those along the equator, which would then blow from west to east. This is because the direction of Earth's rotation influences the direction of the Coriolis effect, which in turn affects wind patterns.

Question 7

Which of the following biomes is correctly paired with the description of its climate?

Accepted Answer

Tropical forests are characterized by nearly constant day length and temperature throughout the year due to their location near the equator. This leads to a stable climate with little variation in temperature across seasons, which is not the case for the other biomes listed.

Question 8

Which of the following graphs illustrates the growth curve of a small population of rodents that has grown to reach a static carrying capacity?

Accepted Answer

The answer of Which of the following graphs illustrates the...

Question 9

Which of the following graphs illustrates the growth over several seasons of a population of snowshoe hares that were introduced to an appropriate habitat also inhabited by predators in northern Canada?

Accepted Answer

The answer of Which of the following graphs illustrates the...

Question 10

A population's carrying capacity

Accepted Answer

The carrying capacity of a population can change as environmental conditions change, such as the availability of resources or the presence of predators. Therefore, option A is the correct answer. Option B is incorrect because the logistic growth model is only an approximation and many factors can affect a population's dynamics. Option C is incorrect because carrying capacity can change over time. Option D is incorrect because carrying capacity may not necessarily increase as the per capita growth rate (r) decreases. Option E is incorrect because populations can exceed their carrying capacity, which can lead to resource depletion and population crashes.

Question 11

According to the logistic growth equation  = r max N

Accepted Answer

The answer of According to the logistic growth equation ...

Question 12

Imagine that you are managing a large game ranch. You know from historical accounts that a species of deer used to live there, but they have been extirpated. You decide to reintroduce them. After doing some research to determine what might be an appropriately sized founding population, you do so. You then watch the population increase for several generations, and graph the number of individuals (vertical axis) against the number of generations (horizontal axis). The graph will likely appear as

Accepted Answer

The graph of the population increase after introducing a new species usually appears as a "J" curve, increasing rapidly with each generation until it reaches the carrying capacity of the habitat, after which it stabilizes.

Quiz 40: Population Ecology and the Distribution of Organisms