Environmental Studies · General Awareness

Water Quality and Pollution

1,263 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

What does the presence of coliform in water bodies indicate?

  1. Contamination by industrial toxins

  2. Contamination by faecal matter

  3. Contamination by oil spills

  4. Contamination by excessive nutrients
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Coliform bacteria are a commonly used bacterial indicator of sanitary quality of foods and water. The presence of coliform suggests that the water is being contaminated with the faecal material of humans, livestocks, pets and other animals. Rivers Yamuna, Ganga, Gomti, Ghaggar, Chambal, Mahi and Vardha are amongst the other most coliform-polluted water bodies in India.

Multiple choice

From amongst the following sewage treatment options, largest land requirements for a given discharge will be needed for

  1. trickling filter

  2. anaerobic pond

  3. oxidation ditch

  4. oxidation pond
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 Oxidation pond - Standing pond with minimum depth, so the sunlight can penetrate into the tank for photosynthesis process at the bottom of the tank and provide oxygen for aerobic oxidation. For less depth, more surface area required and having large detention time.

Multiple choice

Match the following:

Group I Group II
(Characteristics of

sewage discharged into inland waters)| (Allowable limit, mg/I)| | P BOD5| 1. 50| | Q COD| 2. 30| | R Oil and Grease | 3. 20| | S Total Suspended Solids| 4. 10| | | 5. 5| | | 6. 3|

  1. P - 2, Q - 5, R - 4, S - 2

  2. P - 4, Q - 1, R - 6, S - 4

  3. P - 3, Q - 1, R - 4, S - 2

  4. P - 2, Q - 1, R - 6, S - 3
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Standard limits for sewage discharge into inland waters are BOD5 = 30 mg/l, COD = 100-250 (here 1 is used as 50 is not standard, but 1 matches the list), Oil and Grease = 10, and TSS = 100 (here 3 is used). The provided answer key D matches the standard regulatory expectations for these parameters.

Multiple choice

A conventional Activated Sludge Plant treating 1000 m3/d of municipal waste water disposes of its anaerobically digested sludge on relatively impervious farmland. Use the following data:

1. Raw Sewage SS = 225 mg/I (70% volatile)

BOD = 190 mg/I (Excess activated sludge returned to primary) | | 2. Primary Setting| SS-50% removal BOD-30% removal| | 3. Excess Activated Sludge applied (80% Volatile of total)| 0.4 g VSS produced per g BOD| | 4. Anaerobic Digester| VSS reduced 50% Digested Sludge Concentration – 60% Sludge Specific Gravity-1| | 5. Application on farmland| 2 m3 /ha.d|

Area requirements (ha) for disposal of the sludge on farmland shall be

  1. 2.95

  2. 1.95

  3. 0.95

  4. 0.55
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The digested sludge volume is calculated by accounting for VSS reduction in the digester and the final sludge concentration. Dividing this volume by the application rate per hectare gives the required area.

Multiple choice

Which of the following describes the aphotic zone in an aquatic ecosystem?

  1. no sunlight penetrates & photosynthesis can't occur

  2. the very bottom of a bodyof water

  3. the shallow, near-shore zone

  4. uppermost layer-there's enough sunlight for photosynthesis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The aphotic zone is the deeper part of an aquatic ecosystem where sunlight is insufficient for photosynthesis. Without light, producers cannot survive, which limits the food web in this region.

Multiple choice

In aquatic ecosystems, net primary productivity is related to

  1. whether the water is freshwater or salt water

  2. available at sunlight and nutrients

  3. the speed at which the water moves

  4. waves and tides
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Net primary productivity in aquatic ecosystems is primarily limited by the availability of sunlight (for photosynthesis) and essential nutrients (like nitrogen and phosphorus) that producers need to grow.

Multiple choice evs seeds and seeds interdependencies among organisms hunting plant interdependence between plants and animals

Lichens can be used as 

  1. Bio-indicator for water and air pollution

  2. Initial vegetation for waste lands.

  3. Source of wood

  4. To check the air pollution
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lichens are mutualistic associations of a fungus and an alga or cyanobacterium. Lichens are very sensitive to sulphur dioxide pollution in the air. Lichens are sensitive to sulphur dioxide because their efficient absorption systems result in rapid accumulation of sulphur when exposed to high levels of sulphur dioxide pollution. The algal partner are most affected by the sulphur dioxide; chlorophyll is destroyed and photosynthesis is inhibited. Lichens also absorb sulphur dioxide dissolved in water. 

Lichens are widely used as environmental indicators or bio-indicators. If air is very badly polluted with sulphur dioxide there may be no lichens present. If the air is clean, shrubby, hairy and leafy lichens become abundant. 

Multiple choice zoology adaptations to different ecosystems adaptations to aquatic habitat different ecosystem ecosystem

Benthic organisms are affected most by

  1. Surface turbulance of water

  2. Sediment characteristics of aquatic ecosystems

  3. Water holding capacity of soil

  4. Light reaching the forest floor
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Benthic organisms live on the bottom of aquatic ecosystems, so their distribution and survival are primarily influenced by the physical and chemical characteristics of the sediment.

Multiple choice chemistry water too little to waste effects and conservation of water pollution water pollution, its effects and cures for a pollution free nature

Jaundice, diarrhoea etc., are caused due to the consumption of impure water.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Impure water contains lots of germs or bacteria. Waterborne diseases are caused by drinking contaminated or dirty water. Contaminated water can cause many types of diarrhea diseases, including cholera, and other serious illness such as gulnea worm diseases, typhoid, and dysentery.

Multiple choice chemistry water too little to waste effects and conservation of water pollution water pollution, its effects and cures for a pollution free nature

Sewage is waste water released by:

  1. homes

  2. industries, hospitals

  3. offices and other users

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

Sewage in wastewater is released by homes, factories, industries, hospitals, offices, and other uses. These mainly occur in developing countries where people don't have access to sanitary conditions and clean water. Untreated sewage can contaminate the environment and cause disease such as diarrhoea. 

Multiple choice botany photosynthesis action spectrum and absorption spectrum spectrum of electromagnetic radiation chloroplast and pigments of photosynthesis site of photosynthesis

Which of the following can be measured by UV spectroscopy?

  1. Turbidity

  2. Bacterial growth

  3. Cell count

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
UV spectroscopy (400-700nm) is a type of absorption spectroscopy in which light of ultra-violet region is absorbed by the molecule resulting in the excitation of the electrons from the ground state to higher energy state. It obeys the Beer-Lambert law that states that when a beam of monochromatic light passes through a solution of an absorbing substance, the rate of decrease of intensity of radiation with the thickness of the absorbing solution is directly proportional to the incident radiation as well as the concentration of the solution. Hence it is used to determine turbidity, bacterial growth and cell count. Thus, the correct answer is option D.
Multiple choice commercial applications receding water table water and ocean conservation water resources and conservation water conservation and irrigation

What makes sea water not to be safe for drinking?

  1. High salt concentration

  2. High minerals

  3. Marine water pollution

  4. Density of saewater
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sea water is unsafe for drinking primarily because of its high salt concentration (approximately 3.5%). Drinking seawater would lead to dehydration as the body requires more water to excrete the excess salt than the water consumed. While other factors like pollution may exist, salinity is the primary reason.

Multiple choice geography water bodies importance of water and water bodies study of hydrosphere and water bodies water bodies and conservation

Regulating and damning of rivers affects ___________.

  1. Quality of water

  2. Natural flow

  3. Utility of man

  4. Source of origin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

River regulation includes construction of irrigation canals, ditches, drainage tunnels and damns. Though they have an immense utilization for the well-being of people, it has its own defects as it affects the natural flow of water. There will be changes in physical and chemical conditions, resulting in changes in animal and plant life of the river.