Question 1

-Which of these lines depicts a population being affected by limited resources?

Accepted Answer

The answer of 
-Which of these lines depicts a population...

Question 2

In a terrestrial food web,which of the following categories of organisms will have the highest total energy content and biomass?

Accepted Answer

Primary producers have the highest total energy content and biomass in a terrestrial food web because they are the base of the food chain and have the ability to convert sunlight into energy through photosynthesis. As energy moves up the food chain, there is a decrease in the amount of available energy, resulting in lower energy content and biomass for higher trophic levels such as consumers, herbivores, and carnivores.

Question 3

Many strategies have been used to control leafy spurge,including the deliberate introduction of different species of flea beetles that feed on leafy spurge.Each flea beetle female may lay about 200 eggs in her only year of life.In places where flea beetle introductions have quickly established large populations that have grown and stabilized,a graph of the population growth of these beetles most likely would look like ___________ .

Accepted Answer

An S-shaped curve is typically seen in population growth when a new species is introduced and the population initially grows rapidly and then stabilizes due to limiting factors such as resources or predators.

Question 4

Plants such as leafy spurge can double their population size every year in part because of their efficient production of large amounts of seeds.Populations that can double every year,such as leafy spurge,__________.

Accepted Answer

Populations that can double every year exhibit exponential growth as they rapidly spread to new regions. However, there may be limiting factors such as resources or predators that eventually slow down their growth and lead to logistic growth. Choice A is incorrect because populations cannot grow indefinitely due to limitations in resources and space. Choice D is not necessarily true as some populations may not have predators, while others may have effective defense mechanisms against predation.

Question 5

Read the following scenario, and answer the questions below.

In North America, a toxic weed called leafy spurge was accidentally introduced and has grown and spread rapidly, covering millions of acres in north- central United States and south- central Canada. Leafy spurge is generally avoided by cattle and horses and may be toxic to them. Thus, rangeland where leafy spurge has spread has been damaged by the invasion of this plant.

-Flea beetles alone are unlikely to eliminate all of the leafy spurge in a region.Instead,the number of leafy spurge plants and the number of flea beetles in a particular community may stabilize.At such a point,the leafy spurge and flea beetle populations __________.

Accepted Answer

Ecological resistance occurs when a population is able to maintain its size despite being subjected to pressure from a predator or other source of mortality. In this case, the leafy spurge population is being controlled by the flea beetle population, but the beetle population itself is not growing exponentially. Instead, it has reached a stable equilibrium with the leafy spurge population. This suggests that the two populations are experiencing ecological resistance.

Question 6

Why is the sea otter considered a keystone species in areas of the Pacific Ocean?

Accepted Answer

Sea otters are considered a keystone species in areas of the Pacific Ocean because they play a crucial role in maintaining the balance of the ecosystem by controlling the population of sea urchins, which are herbivores that graze on kelp forests. Without sea otters, the sea urchin population would increase, and they would overgraze on kelp forests, leading to the disappearance of the kelp forest ecosystem.

Question 7

Which of the following represents a type of mutualism?

Accepted Answer

Mutualism is a type of symbiotic relationship where both species involved benefit. In this case, the honeybee benefits by feeding on the nectar of the flower, while also accidentally pollinating the plant, which benefits the plant by allowing it to reproduce.

Question 8

If too many of a certain species of game fish are caught,the population will crash and future years of fishing in the lake will suffer.Your job as a fisheries and wildlife officer is to decide how many fish you should allow to be harvested so as to sustain the sport fishing industry while maintaining the fish population.Assuming the fish population normally experiences logistic population growth,which of the following options would seem to make the most sense in managing this fish population?

Accepted Answer

Allowing harvesting to a level of half of the species' carrying capacity would ensure that the fish population does not crash while still allowing for sustained sport fishing. This approach would keep the fish population at a healthy level while also allowing for some harvesting that can benefit the sport fishing industry. Allowing harvesting only above the species' carrying capacity (B) or to the full carrying capacity (C) would be too risky and could lead to a population crash. Allowing harvesting to a level of 1/10 of the species' carrying capacity (D) would be too conservative and could limit the potential benefits for the sport fishing industry.

Question 9

What makes up an ecological community?

Accepted Answer

An ecological community is a group of populations of different species that interact with each other within a specific area. Therefore, the best answer is D, which includes all of the plants, animals, and other organisms interacting in a specific area. Choices A and B are too limited in their scope, and choice C only refers to humans and not the complete range of organisms that make up an ecological community.

Question 10

Along the shoreline of a pond,Canada geese,American toads,and grass frogs search for food while bluegill and bass prey on small fish in the shallow water.These species,living and feeding in this particular location,represent an____________.

Accepted Answer

The group of Canada geese, American toads, grass frogs, bluegill, and bass all living and interacting in the pond shoreline represent a community. A community is a group of different species living in the same area and interacting with each other.

Question 11

A population's growth rate is determined by _________.

Accepted Answer

A population's growth rate is determined by the combination of birth, death, immigration, and emigration rates. Birth and immigration rates contribute to population growth, while death and emigration rates decrease the population. The interplay of these factors results in either an increase or decrease in the overall population size. Therefore, option D is the best choice.

Question 12

-Which survivorship curve in the figure depicts a species that has a high death rate early in life,followed by a period of low death rate early in adulthood,and then a period of high death rate later in life?

Accepted Answer

The answer of 
-Which survivorship curve in the figure depicts...

Question 13

In logistic population growth,how does population growth change as the population nears its carrying capacity?

Accepted Answer

As the population approaches its carrying capacity, the resources become limited, competition for resources increases, and the growth rate slows down, which results in a decrease in population growth. Eventually, the population may reach an equilibrium point where the birth rate and death rate are equal, resulting in a stable population size.

Question 14

Read the following scenario, and answer the questions below.

In North America, a toxic weed called leafy spurge was accidentally introduced and has grown and spread rapidly, covering millions of acres in north- central United States and south- central Canada. Leafy spurge is generally avoided by cattle and horses and may be toxic to them. Thus, rangeland where leafy spurge has spread has been damaged by the invasion of this plant.

-Leafy spurge has spread across many U.S.states.If left uncontrolled in these states,leafy spurge populations will _________ .

Accepted Answer

If left uncontrolled, the population will continue to grow and eventually reach their carrying capacity - the maximum number of individuals the environment can support with available resources.

Question 15

-Which line in the figure represents the survivorship curve for humans?

Accepted Answer

Line C typically represents the survivorship curve for humans, characterized by high survival rates in early and middle life, followed by a rapid decline in survival in old age.

Question 16

-Which of these lines depicts a population with a constant growth rate?

Accepted Answer

A population with a constant growth rate would be represented by a straight line when plotted on a graph, indicating a linear increase over time. This is what option C would depict.

Question 17

An organism's range of tolerance is best exemplified by which of the following?

Accepted Answer

An organism's range of tolerance refers to the range of environmental conditions, such as temperature, moisture, or pH, within which it can survive and reproduce. The span between the minimum and maximum temperature in which an organism can flourish is a good example of range of tolerance because it shows the limits of the organism's ability to tolerate temperature variations. Option A is incorrect because food availability is not part of an organism's range of tolerance. Option C is too general and vague to be a good example. Finally, option D is too specific to sunlight and does not include all possible environmental factors that could affect an organism's range of tolerance.

Question 18

Which of the following is analogous to mutualism?

Accepted Answer

Mutualism is a type of symbiotic relationship where both organisms benefit from each other. In option A, the basketball player benefits from the company by receiving payment while the company benefits from the advertising the player provides by wearing their shoes.

Question 19

Read the following scenario, and answer the questions below.

In North America, a toxic weed called leafy spurge was accidentally introduced and has grown and spread rapidly, covering millions of acres in north- central United States and south- central Canada. Leafy spurge is generally avoided by cattle and horses and may be toxic to them. Thus, rangeland where leafy spurge has spread has been damaged by the invasion of this plant.

-Some flea beetles escape from a ship and fly to a small island covered with grass but with no trees or beetle predators.As the beetles feed,they destroy all the grasses.But with abundant food,the beetle population soars,doubling in size every month.After about a year,the population crashes as thousands of beetles have destroyed almost all of the plants,and there is little left to feed the large population.This scenario best illustrates ________.

Accepted Answer

The scenario describes exponential growth (doubling in size every month) followed by a population crash due to a lack of resources, which is characteristic of the exponential growth model. The fact that there are no predators or competition is also consistent with this model. Therefore, the best choice is D, exponential growth followed by a population crash.

Question 20

Biocontrol strategies are most likely to work on which one of the following invasive species?

Accepted Answer

Biocontrol strategies are often more effective on plant species like Tamarisk, where specific herbivores or pathogens can be introduced to control the population without affecting other species.

Quiz 16: Human Health and the Environment

-Which of these lines depicts a population being affected by limited resources?

In a terrestrial food web,which of the following categories of organisms will have the highest total energy content and biomass?

Plants such as leafy spurge can double their population size every year in part because of their efficient production of large amounts of seeds.Populations that can double every year,such as leafy spurge,__________.

Why is the sea otter considered a keystone species in areas of the Pacific Ocean?

Which of the following represents a type of mutualism?

What makes up an ecological community?

Along the shoreline of a pond,Canada geese,American toads,and grass frogs search for food while bluegill and bass prey on small fish in the shallow water.These species,living and feeding in this particular location,represent an____________.

A population's growth rate is determined by _________.

-Which survivorship curve in the figure depicts a species that has a high death rate early in life,followed by a period of low death rate early in adulthood,and then a period of high death rate later in life?

In logistic population growth,how does population growth change as the population nears its carrying capacity?

-Which line in the figure represents the survivorship curve for humans?

-Which of these lines depicts a population with a constant growth rate?

An organism's range of tolerance is best exemplified by which of the following?

Which of the following is analogous to mutualism?

Biocontrol strategies are most likely to work on which one of the following invasive species?