ENV 101 Final Exam V2 | ENV 101
Environmental Science | StraighterLine |
Q&A with Rationale (StraighterLine
ENV101 Final Exam)
1. Which of the following terms refers to the number of different species present in a specific
community?
A. Genetic diversity
B. Species evenness
C. Species richness
D. Ecosystem diversity
Answer: C
Rationale: Species richness is a simple count of the different species found within a
community or ecosystem. This is distinct from species evenness, which measures the
relative abundance of individuals within those species. Maintaining high levels of species
richness is essential for providing ecosystem services and ensuring environmental stability.
2. In the Demographic Transition Model, which stage is characterized by high birth rates and
rapidly declining death rates?
A. Stage 1 (Pre-industrial)
B. Stage 4 (Post-industrial)
,C. Stage 3 (Industrial)
D. Stage 2 (Transitional)
Answer: D
Rationale: Stage 2 of the demographic transition occurs as a society begins to industrialize
and improve medical care. During this phase, death rates drop due to better sanitation and
food security while birth rates remain high. This results in the most rapid population
growth seen in the entire transition model.
3. The process by which certain toxins, such as methylmercury, increase in concentration at
higher levels of the food chain is known as:
A. Bioaccumulation
B. Eutrophication
C. Bioremediation
D. Biomagnification
Answer: D
Rationale: Biomagnification occurs when persistent, fat-soluble toxins are passed from
one trophic level to the next. Because consumers must eat large quantities of biomass from
lower levels, the concentration of the toxin increases significantly as it moves up the
pyramid. This phenomenon poses the greatest health risk to top-level predators like eagles,
sharks, and humans.
, 4. What is the primary cause of the current global trend in ocean acidification?
A. Industrial chemical spills
B. Increased uptake of CO2 from the atmosphere
C. Agricultural runoff of nitrogen
D. Thermal pollution from power plants
Answer: B
Rationale: When the oceans absorb carbon dioxide from the atmosphere, the gas reacts
with seawater to form carbonic acid. This process lowers the pH of the water, making it
more acidic over time. Increased acidity interferes with the ability of marine organisms,
such as corals and shellfish, to build their calcium carbonate skeletons.
5. Which soil horizon is primarily composed of organic matter in various stages of
decomposition?
A. O horizon
B. B horizon
C. A horizon
D. C horizon
Answer: A
Rationale: The O horizon, or organic layer, consists of leaf litter and other organic debris
on the very surface of the soil. Below this layer is the A horizon, which contains a mix of
Environmental Science | StraighterLine |
Q&A with Rationale (StraighterLine
ENV101 Final Exam)
1. Which of the following terms refers to the number of different species present in a specific
community?
A. Genetic diversity
B. Species evenness
C. Species richness
D. Ecosystem diversity
Answer: C
Rationale: Species richness is a simple count of the different species found within a
community or ecosystem. This is distinct from species evenness, which measures the
relative abundance of individuals within those species. Maintaining high levels of species
richness is essential for providing ecosystem services and ensuring environmental stability.
2. In the Demographic Transition Model, which stage is characterized by high birth rates and
rapidly declining death rates?
A. Stage 1 (Pre-industrial)
B. Stage 4 (Post-industrial)
,C. Stage 3 (Industrial)
D. Stage 2 (Transitional)
Answer: D
Rationale: Stage 2 of the demographic transition occurs as a society begins to industrialize
and improve medical care. During this phase, death rates drop due to better sanitation and
food security while birth rates remain high. This results in the most rapid population
growth seen in the entire transition model.
3. The process by which certain toxins, such as methylmercury, increase in concentration at
higher levels of the food chain is known as:
A. Bioaccumulation
B. Eutrophication
C. Bioremediation
D. Biomagnification
Answer: D
Rationale: Biomagnification occurs when persistent, fat-soluble toxins are passed from
one trophic level to the next. Because consumers must eat large quantities of biomass from
lower levels, the concentration of the toxin increases significantly as it moves up the
pyramid. This phenomenon poses the greatest health risk to top-level predators like eagles,
sharks, and humans.
, 4. What is the primary cause of the current global trend in ocean acidification?
A. Industrial chemical spills
B. Increased uptake of CO2 from the atmosphere
C. Agricultural runoff of nitrogen
D. Thermal pollution from power plants
Answer: B
Rationale: When the oceans absorb carbon dioxide from the atmosphere, the gas reacts
with seawater to form carbonic acid. This process lowers the pH of the water, making it
more acidic over time. Increased acidity interferes with the ability of marine organisms,
such as corals and shellfish, to build their calcium carbonate skeletons.
5. Which soil horizon is primarily composed of organic matter in various stages of
decomposition?
A. O horizon
B. B horizon
C. A horizon
D. C horizon
Answer: A
Rationale: The O horizon, or organic layer, consists of leaf litter and other organic debris
on the very surface of the soil. Below this layer is the A horizon, which contains a mix of
