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

Wetlands are useful for human beings because

Directions: Read the passage and answer the question that follows:

Wetlands are indeed the vital link between water and land. It is the collective term for marshes, swamps, and bogs, found along the edges of streams, rivers, lakes and coastlines. Wetlands can be found in nearly every country and climatic zone. Indeed wetlands are found from the Tundra to the Tropics and on every continent. They are so varied. Some are wet all the time. Some wetlands are large and some are very small. Many have been altered by human activities such as farming, building of roads, dams and towns. Wetlands are regarded wastelands sources of mosquitoes, flies, snakes and diseases. People had negative views about them and they eliminated them. Original wetlands have been destroyed; some of them have been converted into farmland, some others filled by industrial wastes.
Wetlands vary widely because of topography, climate, hydrology, water chemistry and vegetation. Wetlands are the coastal mangrove forests, lake marshes and seasonally flooded lands along river courses. Palm swamps, sea grass beds, salt flats, and coral reefs are common wetlands. They are of two types: tidal wetlands and non-tidal (inland) wetlands. Tidal wetlands are found along the Atlantic, Pacific, Alaskan and Gulf Coasts. The salt water and fluctuating water levels create a difficult environment. Some plants have adapted to the environment of saline conditions. Inland wetlands are common in the margins of lakes and rivers. They include wet meadows dominated by herbaceous plants, swamps and shrubs and tall trees. The prolonged presence of water favours the growth of specially adapted plants.
States and tribes play a critical role in the protection and management of wetlands. With the growth of education, people have started understanding ecological processes and their attitude towards wetlands have changed. They have recognised the ecological significance of the wetlands; they are a source of valuable natural wealth. They help regulating water levels within watersheds; reduce flood and storm damages; and provide fish and wildlife habitat. They support hunting, fishing and other recreational activities.

Wetlands are the most productive ecosystems in the world. They have been described as biological supermarkets as they provide great volumes of food and attract many animal species. A variety of insects, amphibians, reptiles, birds, fish and mammals are found in these wetlands. Many species of birds, animals, rely on wetlands for food, water and shelter. The microbes, insects and wildlife are part of global cycles for water, nitrogen, and sulphur. They store carbon within their plant communities and thus help to moderate climate conditions.

  1. they are a source of economic growth

  2. they are productive ecosystems in nature and a source of natural wealth

  3. they are a source of mosquitoes, flies and snakes

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Option (3) can be rejected straightaway, being negative in connotation. Option (1) is a little far-fetched and not borne by the passage. Option (2) can be directly derived from the last two paragraphs.

Multiple choice

When water is boiled, bubbles can be seen coming up from the bottom of the pan. Which of the following is present in the water?

  1. Live microorganisms

  2. Carbon-dioxide

  3. Dissolved air in water

  4. Atmospheric oxygen entering water

  5. Excess of nitrogen gas in water as in atmosphere
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, when water is boiled, air bubbles can be seen coming up from the bottom of the pan. This simple activity shows that air is present in water.

Multiple choice

Harmful algal blooms occur when colonies of algae grow out of control while producing toxic or harmful effects in organisms. The causative agent for toxic red tides is

  1. Besnoitia

  2. Frenkelia

  3. Neospora

  4. Noctiluca scintillans

  5. Ceratium furca
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Ceratium furca blooms because of coastal eutrophication. Blooms of this species cause toxic red tides (red-brown), damage fish gills and deplete dissolved oxygen causing anoxic conditions

Multiple choice

Swimmers always suffer from the irritation of skin and mucous membranes of the body. Which among the following algae causes such irritation to humans while swimming?

  1. Euglena

  2. Microcystis

  3. Dictyosphaerium anabaena

  4. Nodularia

  5. Oscillatoria
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Oscillatoria, is part of the Blue Green Algae (Cyanobacteria) family. It is blue greenish 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 swimming.

Multiple choice

Biological treatment of water pollution is done with the help of�

  1. Lichens

  2. Fungi

  3. Phytoplankton

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Biological treatment of water pollution uses microorganisms like phytoplankton to consume organic pollutants. Phytoplankton (C) are microscopic aquatic organisms that help purify water naturally. Lichens are typically air quality indicators. Fungi decompose matter but are more common in terrestrial environments. None of the above is incorrect since phytoplankton is valid.

Multiple choice

Water pollution is caused by�

  1. Decay of bodies of aquatic organisms

  2. Rain

  3. Growth of phytoplankton

  4. Industrial effluents
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Industrial effluents contain toxic chemicals and heavy metals that contaminate water bodies. These wastes from factories and manufacturing processes are a major source of water pollution worldwide. The other options are natural processes or part of aquatic ecosystems.

Multiple choice

Sewage water can be purified for recycling with the action of�

  1. Aquatic plants

  2. Penicillin

  3. Micro-organisms

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

Microorganisms like bacteria break down organic matter in sewage through biological treatment processes. Sewage treatment plants use these microbes to purify water before it's recycled or discharged back into water bodies. This is a natural and effective way to treat wastewater.

Multiple choice

Which of the following enhances BOD of water?

  1. Algae

  2. Sand

  3. Moss

  4. Sugar mill
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

BOD (Biochemical Oxygen Demand) measures how much oxygen microorganisms need to decompose organic matter in water. Sugar mills discharge large amounts of organic waste that increases BOD, potentially depleting oxygen levels for aquatic life. Higher BOD indicates more severe pollution.

Multiple choice

If water pollution continues at its present rate, it will eventually�

  1. Make oxygen molecules unavailable to aquatic life

  2. Make nitrates unavailable to aquatic life

  3. Prevent precipitation

  4. Stop the water cycle
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Water pollution reduces dissolved oxygen levels, making oxygen unavailable to aquatic organisms. When organic pollutants decompose, they consume oxygen through bacterial action. This oxygen depletion can lead to fish kills and ecosystem collapse in severely polluted waters.

Multiple choice

What is/are the effect(s) of thermal discharge on river water?

  1. It heats up the water and destroys aquatic life.

  2. It decreases oxygenation.

  3. It increase the toxicity of toxic pollutants.

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

Thermal discharge heats up the water, destroy aquatic life, decreases oxygenation and increase the toxicity of toxic pollutants.

Multiple choice

BOD is increased by:

  1. algae

  2. moss

  3. fern

  4. distillated wastes

  5. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Algae increase BOD (Biochemical Oxygen Demand) in water bodies. When algal blooms die and decompose, bacteria consume significant amounts of oxygen during the decomposition process, leading to higher BOD values that can harm aquatic ecosystems.