Question 1

The West African black rhino,one of four subspecies of rhinoceros,was declared extinct in 2006.Their horns were believed by many to hold medicinal value.What is the most likely reason for the extinction of the West African black rhino?

Accepted Answer

The most likely reason for the extinction of the West African black rhino is overexploitation, as their horns were believed to hold medicinal value and were therefore heavily hunted for human use.

Question 2

A major problem with hotspots is humans moving in and causing

Accepted Answer

When humans move into hotspots, they often clear land for agriculture or development, leading to habitat destruction which threatens the unique species found in those areas.

Question 3

The various endemic cichlid species of Lake Victoria have suffered losses in their population numbers and species due to the introduction of

Accepted Answer

The introduction of the Nile perch, a predatory fish species, has caused significant declines in the population numbers and species diversity of endemic cichlid species in Lake Victoria.

Question 4

In the last 20 years one concern of scientists who study amphibians is that

Accepted Answer

Scientists who study amphibians have been alarmed by the many species that have been declining or going extinct in recent years. This is due to various factors, including habitat loss, pollution, climate change, and disease outbreaks. The decline of amphibians is a concern because they play important roles in ecosystems and their loss could have ripple effects throughout food webs.

Question 5

Ecologists are concerned about amphibian populations because

Accepted Answer

Ecologists are concerned about amphibian populations because they are very sensitive to environmental change. Their declines, deformities, and extinctions may indicate serious problems in the environment, such as pollution, habitat destruction, or climate change. Additionally, amphibians play important roles in food webs and ecosystems, and their loss can have cascading effects on other species.

Question 6

What becomes more likely to occur in a small population? Check all that apply.

Accepted Answer

In small populations, the Allee effect may occur where a decrease in population size leads to a decrease in reproductive success or survival. Increased genetic drift is also more likely since there is less genetic variation present to begin with. A small population is more susceptible to the extinction vortex, where inbreeding and loss of genetic variation leads to a downward spiral towards extinction. Increased genetic diversity (choice C) is less likely to occur in a small population because there are fewer individuals contributing to the gene pool. The edge effect (choice E) refers to the increased effect of habitat fragmentation at the edges of populations and is not necessarily more likely to occur in small populations.

Question 7

When New York City was given a choice to make regarding its drinking water

Accepted Answer

New York City chose to invest in the maintenance of its watershed's ecosystem as a natural means of water purification, rather than opting for the construction of expensive filtration plants or other alternatives. This approach has been recognized for its sustainability and cost-effectiveness in providing clean drinking water.

Question 8

In western Sweden,coastal marine ecosystems have been exposed to discharge of nutrients over several decades.As a result,algal blooms are more common.Algal mats on the sea bottom limit sunlight and alter the amount of dissolved oxygen in the water.Additionally,some algae produce toxic compounds that can enter shellfish.Furthermore,the decomposing algae produces a strong odor.Which statements below correctly match the outcomes to their effects on value of the ecosystem? Check all that apply.

Accepted Answer

The answer of In western Sweden,coastal marine ecosystems have been...

Question 9

Natural colonization can happen in all of the following ways except

Accepted Answer

Natural colonization refers to the ways in which species naturally expand their ranges without direct human intervention. However, people intentionally planting new species on an island is not a natural means of colonization.

Question 10

The degree of allelic diversity of a population is independent of its size.

Accepted Answer

The degree of allelic diversity in a population is directly proportional to the size of the population. A larger population size allows for more opportunities for mutations and genetic recombination, leading to increased diversity. In contrast, a smaller population size may ultimately lead to a reduction in diversity due to genetic drift and the potential loss of rare alleles.

Question 11

A small island has stable populations of plants and animals,including one species of hawk but no other large predators.A ship docks at the island,and the sailors hunt and kill most of the hawks.What would you expect as an immediate consequence?

Accepted Answer

With the removal of the hawks, there would be a decrease in predation of the rodents, leading to an increase in their population. This may also lead to an indirect increase in the population of insects that the rodents feed on. The removal of hawks would not directly affect the populations of plants or fish.

Question 12

A conservation group is deciding what land to preserve.Why might they want to consider an area of land where the ecosystem is partially damaged by a logging contract that cannot be overturned?

Accepted Answer

Conservation groups often focus on fixing damaged land and ecosystems. By preserving an area that has been partially damaged, there is an opportunity for the group to work towards restoring the ecosystem to a healthier state. Additionally, preserving partially damaged land offers an opportunity to prevent further damage and degradation of the ecosystem.

Question 13

The extinction vortex

Accepted Answer

The extinction vortex is a phenomenon that occurs as a population decreases in size, causing the remaining individuals to become more vulnerable to a variety of causes that can lead to extinction. These causes can include genetic drift, inbreeding, loss of genetic diversity, environmental stressors, and other factors. As the population becomes smaller and more weakened, it enters a downward spiral that can be difficult to reverse.

Question 14

One of the important reasons for maintaining biodiversity is to

Accepted Answer

Maintaining biodiversity is important to maintain the genetic diversity of wild relatives of common crops. This diversity can be important for improving crop yield and resilience to environmental stresses, pests, and diseases.

Question 15

Why might the different species of whales fail to recover even though hunting has been banned?

Accepted Answer

Even though hunting has been banned, the different species of whales may fail to recover due to the loss of genetic diversity. Overhunting, combined with habitat loss or degradation, can lead to a reduction in genetic variation, making populations more vulnerable to environmental stressors and limiting their ability to adapt to changing conditions. This can result in reduced fitness, increased susceptibility to diseases, and reduced reproductive success, among other issues. Therefore, the recovery of whale populations may be hindered by this loss of genetic diversity.

Question 16

A small island has stable populations of plants and animals,including one species of hawk but no other large predators.A ship docks at the island,and the ship's cat escapes.If the cat was pregnant,what do you think the sailors are likely to find if they return ten years later?

Accepted Answer

The ship's cat, as a predator, will likely have a negative impact on the prey species of the island. Specifically, ground-nesting bird species may be at risk of predation and potential extinction due to the introduction of a new predator. Ten years is also a significant amount of time for the cat population to establish itself and potentially increase in size.

Question 17

Human caused introductions can occur by which of the following? Check all that apply.

Accepted Answer

The answer of Human caused introductions can occur by which...

Question 18

Which of the following statements about the causes of extinction are true? Check all that apply.

Accepted Answer

A) Probability of extinction varies inversely with population size. This means that smaller populations are at greater risk of extinction than larger populations. This is because smaller populations are more susceptible to random events, such as natural disasters or disease outbreaks, that can decimate their numbers.
B) Ten 10-hectare habitat patches is not the same as one 100-hectare patch. This refers to the fact that fragmented habitats are not as effective at supporting species as larger, intact habitats. Fragmentation can isolate populations and make it difficult for them to access resources or find mates.
C) Habitat loss is currently the major cause of extinction. This is supported by numerous studies and is widely accepted in the scientific community. Habitat loss can occur due to a variety of factors, such as deforestation, urbanization, and agricultural conversion.
D) The prehistoric megafauna of North America were spared from extinction because they coevolved with humans. This statement is false. The prehistoric megafauna of North America, such as mammoths and giant sloths, did not coevolve with humans and went extinct shortly after humans arrived on the continent. Overhunting and other factors have been proposed as potential causes of their extinction.
E) Probability of extinction is greatest for an endemic species. Endemic species are those that are found only in a specific geographic area, such as a particular island or mountain range. Because these species are often isolated and have small populations, they are at greater risk of extinction than more widespread species.

Question 19

Economists have been comparing the monetary value of intact habitats with the value of using (destroying)those habitats (such as for logging or farming).They find

Accepted Answer

Economists generally find that intact habitats are more valuable than destroyed ones in most cases studied. This is because intact habitats provide key services such as water regulation, pollination, and carbon storage, which have significant economic value but are often not recognized in market transactions. In contrast, the short-term economic gains from using habitats (such as logging or farming) often come at the expense of these important ecosystem services, and can lead to long-term economic and environmental costs.

Question 20

Which of the following whale species are recovering their population numbers as a result of whale harvesting regulations?
 I-right whales
II-Pacific gray whales
III-sperm whales
IV-fin whales
V-humpback whales

Accepted Answer

Pacific gray whales and humpback whales are the two species that have been recovering their population numbers as a result of whale harvesting regulations. Therefore, the correct choice is II and V.

Quiz 58: Conservation Biology