Question
Every year, humans deforest millions of hectares of tropical rain forest. Which of the following is a likely consequence of this deforestation?
(A) Increased carbon dioxide will reduce ozone concentrations in
the atmosphere, resulting in higher levels of ultraviolet radiation
on the earth’s surface.
(B) Lower oxygen concentrations in the atmosphere will decrease
the biodiversity of terrestrial animals.
(C) Animal and plant populations will be eliminated as their habitats
are destroyed, leading to a decrease in biodiversity.
(D) Increased carbon dioxide levels in the atmosphere will reduce
plant and algae growth in other biomes.
▶️Answer/Explanation
Ans: C
The most direct consequence of rain forest destruction is the
permanent loss of massive biodiversity. There are numerous other
consequences, including an increase in atmospheric carbon dioxide,
because there are less plants available to fix carbon into organic forms (and if
the land is used for grazing cattle, which are more animals that produce
methane, another greenhouse gas).
Carbon dioxide is a greenhouse gas, but ozone depletion occurs when
pollutants like chlorofluorocarbons (CFCs) are allowed to escape into the
atmosphere. The rain forest is not the major producer of oxygen gas for the
planet.
Question
Scientists have found that the existing populations of a certain species of amphibian are small in number, lacking in genetic diversity, and separated from each other by wide areas of dry land. Which of the following human actions is most likely to improve the long-term survival of the amphibians?
(A) Cloning the largest individuals to counteract the effects of aggressive predation
(B) Reducing the population size by one-fifth to decrease competition for limited resources
(C) Constructing a dam and irrigation system to control flooding
(D) Building ponds in the areas of dry land to promote interbreeding between the separated populations
▶️Answer/Explanation
Ans:D
Question
In the year 2000, specimens of Caulerpa taxifolia, a green alga used in tropical aquariums, were found off the coast of California. Native to the Indian Ocean, C. taxifolia is known for aggressive growth and an ability to compete with sea grasses. It is currently on an international list of invasive species. Which of the following best predicts the consequences of the introduction of C. taxifolia to the California coast?
(A) Without natural herbivores or competitors, C. taxifolia will grow rapidly and crowd out native species of producers.
(B) C. taxifolia will have a hard time establishing itself because it will have to compete against native species of sea grasses, which are better adapted to the environment.
(C) C. taxifolia will grow rapidly, leading to an increase in the diversity of producers.
(D) Because it is not in the Indian Ocean, its natural environment, C. taxifolia will not be able to grow efficiently.
▶️Answer/Explanation
Ans:A
Question
A scientist is evaluating a proposal for raising large numbers of fish in ocean pens for human consumption. As part of the evaluation, the scientist is designing a plan for investigating how the fish in the ocean pens might affect nearby ecosystems. Which of the following is the most appropriate factor to use as the dependent variable in the experimental investigation?
(A) The amount of metabolic wastes in the water where the fish are being raised
(B) The water temperature in the natural habitat of the fish being studied
(C) The types of fish that are preferentially consumed by humans
(D) The amount of time it takes for fish to digest a meal
▶️Answer/Explanation
Ans:A
Question
The area covered by tropical rain forest is reduced by millions of hectares per year due to agriculture and logging. Which of the following best describes a likely result of tropical rain forest deforestation?
(A) Populations of plants and animals will decrease as more rain forest disappears, leading to a decrease in biodiversity.
(B) An increase of soil moisture will lead to a rapid increase in new vegetation coverage.
(C) An increase in atmospheric carbon dioxide will lead to higher levels of ultraviole radiation reaching the surface of Earth.
(D) More oxygen will be available to other organisms as plant numbers decrease.
▶️Answer/Explanation
Ans:A
This option is correct. It demonstrates an understanding of the human impact on ecosystems and correctly predicts that the loss of habitat from deforestation likely will lead to a loss of species diversity due to a decrease of available niches.