- Which of the following is the major cause of desertification?
A) Overgrazing
B) Reforestation
C) Reduced agriculture
D) Increased precipitation
Answer: A) Overgrazing
Explanation:
Overgrazing by livestock reduces vegetation cover, leading to soil degradation and desertification. Without plant cover, soil becomes more prone to erosion by wind and water.
- Which one of the following is a point source of water pollution?
A) Agricultural runoff
B) Sewage treatment plant
C) Urban runoff
D) Atmospheric deposition
Answer: B) Sewage treatment plant
Explanation:
A point source of pollution is any single, identifiable source from which pollutants are discharged. A sewage treatment plant is a point source because its pollution can be traced to a specific location. Agricultural and urban runoff are examples of non-point sources.
- Which of the following is a major pollutant from vehicle exhausts?
A) Sulfur trioxide
B) Methane
C) Carbon monoxide
D) Hydrogen sulfide
Answer: C) Carbon monoxide
Explanation:
Vehicle exhausts emit carbon monoxide (CO), which is a harmful pollutant. CO reduces the ability of blood to carry oxygen and can be fatal in high concentrations.
- Which of the following resources is renewable?
A) Coal
B) Petroleum
C) Natural gas
D) Wind energy
Answer: D) Wind energy
Explanation:
Wind energy is a renewable resource because it is continuously replenished by natural processes. Fossil fuels like coal, petroleum, and natural gas are non-renewable because they take millions of years to form.
- Which of the following is an example of a secondary pollutant?
A) Particulate matter
B) Nitrogen oxide
C) Ozone
D) Carbon monoxide
Answer: C) Ozone
Explanation:
Secondary pollutants are not directly emitted but form in the atmosphere through chemical reactions between primary pollutants. Ozone (O₃) is a secondary pollutant that forms from the reaction of nitrogen oxides and volatile organic compounds in the presence of sunlight.
- Which of the following practices can help in waste management?
A) Incineration without emission control
B) Landfilling without sorting waste
C) Recycling and composting
D) Open burning of plastics
Answer: C) Recycling and composting
Explanation:
Recycling and composting are sustainable waste management practices that reduce the amount of waste sent to landfills and minimize environmental pollution. Incineration without controls, open burning, and unsorted landfilling can cause significant environmental harm.
- Which of the following is the main cause of coral bleaching?
A) Oil spills
B) Global warming and increased sea temperatures
C) Overfishing
D) Plastic pollution
Answer: B) Global warming and increased sea temperatures
Explanation:
Coral bleaching occurs when corals, stressed by warmer sea temperatures, expel the symbiotic algae (zooxanthellae) that give them color. This is primarily due to global warming and is exacerbated by pollution and overfishing.
- Which of the following gases is responsible for the brown color of photochemical smog?
A) Nitrogen dioxide
B) Sulfur dioxide
C) Ozone
D) Carbon dioxide
Answer: A) Nitrogen dioxide
Explanation:
Nitrogen dioxide (NO₂) is responsible for the characteristic brownish haze associated with photochemical smog. It is produced by vehicle emissions and industrial processes.
- Which of the following is a bioindicator of water pollution?
A) Frogs
B) Lichens
C) Coliform bacteria
D) Birds
Answer: C) Coliform bacteria
Explanation:
Coliform bacteria are used as bioindicators of water pollution, especially fecal contamination. Their presence in water suggests the presence of harmful pathogens.
- What is the primary effect of biomagnification on ecosystems?
A) Increase in biodiversity
B) Accumulation of harmful substances in top predators
C) Increase in plant productivity
D) Enhanced soil fertility
Answer: B) Accumulation of harmful substances in top predators
Explanation:
Biomagnification refers to the process where toxic substances, such as pesticides and heavy metals, become more concentrated in organisms higher up the food chain, often leading to health issues for top predators.
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