ENV 101 Exam 4 V1 | ENV 101
Environmental Science | StraighterLine |
Q&A with Rationale (StraighterLine
ENV101 Exam 4)
1. Which of the following describes the largest reservoir of fresh water on Earth?
A. Groundwater aquifers
B. Glaciers and ice caps
C. Lakes and rivers
D. The atmosphere
Answer: B
Rationale: Glaciers and polar ice caps contain approximately 68.7% of the world’s fresh
water. Although groundwater is the largest source of liquid fresh water, it is significantly
less than the amount trapped in ice. Lakes and rivers contain a very small percentage of the
total freshwater supply.
2. What is the primary cause of cultural eutrophication in aquatic ecosystems?
A. Heavy metal contamination
B. Excessive nutrient runoff like nitrogen and phosphorus
C. Thermal pollution from power plants
D. Acid rain deposition
,Answer: B
Rationale: Cultural eutrophication is caused by human activities that increase nutrient
input into water bodies. Runoff from agricultural fertilizers and sewage discharge are the
most common sources of nitrogen and phosphorus. This process leads to algae blooms,
which eventually deplete oxygen and harm aquatic life.
3. In the context of wastewater treatment, what is the primary goal of the secondary
treatment phase?
A. Biological degradation of dissolved organic matter
B. Disinfection using UV light or chlorine
C. Removal of large debris and grit
D. Removal of dissolved heavy metals
Answer: A
Rationale: Secondary treatment utilizes aerobic bacteria to break down organic waste
through biological processes. This step typically involves aeration tanks where
microorganisms consume the organic material. It is a critical stage in reducing the
biochemical oxygen demand (BOD) of the effluent.
4. Which layer of the atmosphere contains the ozone layer that protects Earth from UV
radiation?
A. Troposphere
B. Mesosphere
, C. Stratosphere
D. Thermosphere
Answer: C
Rationale: The stratosphere is located directly above the troposphere and contains the
ozone layer. This ozone absorbs the majority of the sun’s harmful ultraviolet radiation,
preventing it from reaching the surface. Without this protection, life on land would face
significant DNA damage and high rates of skin cancer.
5. What is a ‘point source’ of water pollution?
A. A specific discharge pipe from a factory
B. Atmospheric deposition of mercury
C. Runoff from a large agricultural field
D. Urban runoff from city streets
Answer: A
Rationale: A point source is any single identifiable source of pollution from which
pollutants are discharged. Examples include pipes, ditches, or factory smokestacks where
the origin is discrete and easily regulated. In contrast, non-point sources like agricultural
runoff come from broad, diffuse areas.
6. Which of the following is considered a primary air pollutant?
A. Ground-level ozone
Environmental Science | StraighterLine |
Q&A with Rationale (StraighterLine
ENV101 Exam 4)
1. Which of the following describes the largest reservoir of fresh water on Earth?
A. Groundwater aquifers
B. Glaciers and ice caps
C. Lakes and rivers
D. The atmosphere
Answer: B
Rationale: Glaciers and polar ice caps contain approximately 68.7% of the world’s fresh
water. Although groundwater is the largest source of liquid fresh water, it is significantly
less than the amount trapped in ice. Lakes and rivers contain a very small percentage of the
total freshwater supply.
2. What is the primary cause of cultural eutrophication in aquatic ecosystems?
A. Heavy metal contamination
B. Excessive nutrient runoff like nitrogen and phosphorus
C. Thermal pollution from power plants
D. Acid rain deposition
,Answer: B
Rationale: Cultural eutrophication is caused by human activities that increase nutrient
input into water bodies. Runoff from agricultural fertilizers and sewage discharge are the
most common sources of nitrogen and phosphorus. This process leads to algae blooms,
which eventually deplete oxygen and harm aquatic life.
3. In the context of wastewater treatment, what is the primary goal of the secondary
treatment phase?
A. Biological degradation of dissolved organic matter
B. Disinfection using UV light or chlorine
C. Removal of large debris and grit
D. Removal of dissolved heavy metals
Answer: A
Rationale: Secondary treatment utilizes aerobic bacteria to break down organic waste
through biological processes. This step typically involves aeration tanks where
microorganisms consume the organic material. It is a critical stage in reducing the
biochemical oxygen demand (BOD) of the effluent.
4. Which layer of the atmosphere contains the ozone layer that protects Earth from UV
radiation?
A. Troposphere
B. Mesosphere
, C. Stratosphere
D. Thermosphere
Answer: C
Rationale: The stratosphere is located directly above the troposphere and contains the
ozone layer. This ozone absorbs the majority of the sun’s harmful ultraviolet radiation,
preventing it from reaching the surface. Without this protection, life on land would face
significant DNA damage and high rates of skin cancer.
5. What is a ‘point source’ of water pollution?
A. A specific discharge pipe from a factory
B. Atmospheric deposition of mercury
C. Runoff from a large agricultural field
D. Urban runoff from city streets
Answer: A
Rationale: A point source is any single identifiable source of pollution from which
pollutants are discharged. Examples include pipes, ditches, or factory smokestacks where
the origin is discrete and easily regulated. In contrast, non-point sources like agricultural
runoff come from broad, diffuse areas.
6. Which of the following is considered a primary air pollutant?
A. Ground-level ozone
