Environmental Studies · General Awareness

Water Quality and Pollution

1,303 Questions

Water Quality and Pollution examines the sources, mechanisms, and impacts of contaminants in aquatic ecosystems. It covers crucial environmental concepts like eutrophication, biochemical oxygen demand, and thermal pollution. This subject frequently appears in general science and environmental studies sections of various examinations.

Eutrophication CausesThermal Pollution EffectsBiochemical Oxygen DemandSynthetic Fertilizer ImpactsWastewater SourcesAquatic Ecosystem Toxicity

Water Quality and Pollution Questions

Multiple choice

BOD level in fresh water should not exceed beyond:

  1. 5 ppm

  2. 10 ppm

  3. 25 ppm

  4. 50 ppm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

BOD (Biochemical Oxygen Demand) measures the amount of dissolved oxygen consumed by microorganisms in water. A BOD level of 5 ppm is the standard maximum acceptable limit for fresh water to maintain aquatic life and prevent oxygen depletion. Higher BOD levels indicate organic pollution and can lead to eutrophication.

Multiple choice

While swimming Arun suffered from the irritation of skin and mucous membranes of the body. Which of the following algae causes such irritation to humans while swimming?

  1. Oscillatoria

  2. Nodularia

  3. Dictyosphaerium Anabaena

  4. Microcystis

  5. Euglena
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Oscillatoria is part of the blue-green Algae (Cyanobacteria) family. It is blue-green in colour, usually free floating, cylindrical or sometimes slightly tapering, unbranched filaments in aquatic environments. It is implicated in irritation of skin and mucous membranes suffered by people while swimming.

Multiple choice

Continuous sewage flow into a stream would lead to

  1. Eutrophication

  2. Algal Bloom

  3. Depletion of oxygen

  4. Increase in temperature
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Continuous sewage flow introduces organic matter and nutrients that stimulate excessive bacterial growth. These bacteria consume oxygen for decomposition, leading to oxygen depletion. Eutrophication and algal blooms are earlier stages; oxygen depletion is the direct consequence that harms aquatic life.

Multiple choice

A city’s sewage was disposed into a water body. It was noticed that the aquatic animals in the body started dying. What effect of sewage led to the death of aquatic life?

  1. Utilisation of oxygen from water body

  2. Utilisation of CO2 from water

  3. Increasing temperature of water body

  4. Increasing metal content in water body
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sewage is an oxygen-consuming material. It decreases the oxygen content of the water body and thus, the amount of oxygen available for aquatic organisms decreases.

Multiple choice

Biological magnification occurs in environment as a result of water pollution. Which of the following factors may be involved in biological magnification?

  1. Chlorinated hydrocarbons

  2. Oil spills

  3. Sewage water

  4. Chlorofluorocarbons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Chlorinated hydrocarbons are present in pesticides and are involved in biological magnification. These chemicals may be selectively accumulated by organisms to much larger concentrations than that can cause toxicity.

Multiple choice

Which of the following is the effect of siltation in water pollution?

  1. Reduction in primary production

  2. Excessive growth of phytoplanktons

  3. Heavy mortality among fishes

  4. Rapid multiplication of dinoflagellates
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Siltation is the phenomenon by which the gills of fishes are deposited with silt. This causes heavy mortality among fishes.

Multiple choice

Eutrophication of lacks is consequence effect of the accumulation of

  1. Silt load

  2. Sewage

  3. Nitrates and Phosphates

  4. Vegetation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Eutrophication occurs when a body of water receives an excess of nutrients, specifically nitrates and phosphates, often from agricultural runoff or detergents. This nutrient overload leads to algal blooms, which deplete oxygen levels and harm aquatic life.

Multiple choice

Despite protests from industry, pollution control board officials have ordered the levels of microorganisms in various water bodies to be measured and that the results be published.

  1. the levels of microorganisms in various water bodies to be measured and that the results be published

  2. that various water bodies should be measured for their levels of microorganisms, with the results being

  3. the measure of levels of microorganisms in various water bodies and the results to be

  4. various water bodies measured for levels of microorganisms, with their results

  5. that the levels of microorganisms in various water bodies be measured and the results
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The subjunctive mood must be used with order or recommendation verbs like order, mandate, recommend, ask and demand. To properly use the subjunctive, the sentence structure is: [subject] [verb] that [next subject] [infinitive form of next verb, without "to"]. The missing 'that' makes options (1), (3) & (4) unsuitable. Option (2) has 'should' a term that becomes redundant with an order or recommendation verb. Hence (5).

Multiple choice

________ gives green color to water.

  1. Melanin

  2. Phytoplankton

  3. Fungi

  4. Amoeba

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Phytoplankton are microscopic marine algae that contain chlorophyll, which gives water a green appearance, especially in nutrient-rich areas.

Multiple choice

Acid rain can cause

  1. water to become polluted

  2. fish to die

  3. damage to buildings

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Acid rain is a broad environmental issue that lowers the pH of water bodies, harming aquatic life, and chemically weathers stone and metal structures.

Multiple choice

Which of the following statements is incorrect regarding algal blooms?

  1. The freshwater and ocean blooms have been found to be anthropogenic.

  2. Looms may be observed in freshwater aquariums.

  3. Freshwater algal blooms are the result of deficiency of nutrients.

  4. Bright green blooms are a result of cyanobacteria.

  5. Red tide is a term often used to describe HABs in marine coastal areas.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Freshwater algal blooms are the result of an excess of nutrients, particularly some phosphates.