Question 1

The population shown in the pyramid is:

Accepted Answer

The answer of The population shown in the pyramid is:...

Question 2

Which population represented on the graph has the highest biotic potential?

Accepted Answer

The population represented by the line on the left has the highest biotic potential because it has the highest carrying capacity.

Question 3

Zebra mussels were introduced into Lake St. Clair around 1988. The table lists the population densities (in grams dry weight per square meter of lake bottom)of native unionid mussels and exotic zebra mussels in the lake before and after this introduction. Both groups feed by filtering small particles from the water. Based on the information given, which of the following BEST describes the likely relationship between zebra mussels and unionids?

Accepted Answer

The answer of Zebra mussels were introduced into Lake St....

Question 4

Which tends to be more intense: intraspecific or interspecific competition? Why?

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The answer of Which tends to be more intense: intraspecific...

Question 5

Why has it been so hard to come up with an accurate measure of Earth's carrying capacity for humans?

Accepted Answer

The answer of Why has it been so hard to...

Question 6

The population shown in the graph is demonstrating:

Accepted Answer

The answer of The population shown in the graph is...

Question 7

-According to the graph, how long does it take the population of organisms represented by the middle line to reach 1,000 bacteria?

Accepted Answer

The graph shows that the middle line reaches 1,000 bacteria at the 4-hour mark.

Question 8

A small country begins to experience stable economic prosperity after centuries of extreme poverty. The government uses the taxes generated for educating all members of the population and creating a comprehensive health care system for all its citizens. A social security system is established to support elderly members of the population. What demographic changes would you expect to see?

Accepted Answer

With the implementation of comprehensive healthcare and education, individuals are likely to have better access to family planning resources, resulting in a decrease in deaths and an increase in the number of births. Additionally, improved living conditions may allow individuals to delay having children until later in life.

Question 9

At the start of a study, 200 spotted owls lived in an old-growth forest patch in western Oregon. During the next year, a biologist tracking the birds observed that 25 new birds hatched and 5 died. What was r for this year?

Accepted Answer

The answer of At the start of a study, 200...

Question 10

During the winter of 1999, minimum temperatures did not get much below freezing in an Oregon pond, and the following summer, large mosquito populations were observed. In the winter of 2000, frost came early and most ponds were frozen for 3 months. The following summer, very small mosquito populations were observed. This is an example of:

Accepted Answer

This is an example of density-independent regulation because the mosquito population changes were influenced by abiotic factors (temperature and frost) rather than the density of the population itself.

Question 11

Based on its population pyramid, this population:

Accepted Answer

The population pyramid shows a wide base indicating a high number of young individuals and a narrowing top indicating a lower number of old individuals. This indicates a high birth rate and a low death rate, which is characteristic of an expanding population.

Question 12

An ecologist is studying the painted turtle population in a small pond. At the beginning of the year, there are 100 individuals. Over the course of a year, 40 turtles are born and 60 die. There is no migration. What is the birth rate per year for this population?

Accepted Answer

The answer of An ecologist is studying the painted turtle...

Question 13

What factors determine Earth's carrying capacity for humans?

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The answer of What factors determine Earth's carrying capacity for...

Question 14

A laboratory experiment followed the growth of a flour beetle (Tribolium sp.)population over time. At first the population increased dramatically, but later the growth slowed and the population size leveled off. Although food (the wheat flour in which they live)was still abundant, the flour beetles resorted to eating their own eggs when population densities got high. What can we conclude about cannibalism in this species?

Accepted Answer

The fact that the flour beetles resorted to cannibalism when population densities got high suggests that it is a density-dependent means of population control. This makes sense, as when populations are denser, there is greater competition for limited resources and individuals may resort to eating each other to survive. This also explains why the population growth slowed and leveled off despite abundant food: the population was self-regulating through cannibalism as a result of density-dependent factors.

Question 15

An ecologist is studying the painted turtle population in a small pond. At the beginning of the year, there are 100 individuals. Over the course of a year, 40 turtles are born and 60 die. There is no migration. What is the growth rate (r)of the painted turtle population?

Accepted Answer

The growth rate (r) can be calculated using the formula:
r = (births - deaths) / population size

Plugging in the given information, we get:
r = (40 - 60) / 100
r = -20 / 100
r = -0.2

Note that the growth rate is negative, which means that the population is decreasing. To get the actual growth rate (which is usually positive), we can take the absolute value:
r = | -0.2 | = 0.2

Therefore, the correct answer is B) 0.2.

Question 16

Many species of field mice are able to reproduce several times a year and produce litters with multiple offspring. However, an ecologist noted that the population size of mice, as measured in a California grassland, did not change from year to year. The factors that keep natural populations from increasing are collectively called:

Accepted Answer

The fact that the population size of mice did not change from year to year suggests that the population is being held in check by factors that limit its growth, such as limited resources or predation. These factors are collectively known as environmental resistance.

Quiz 26: Population Growth and Regulation