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Water Pollution MCQ for NEET Biology With Answers

Prepare for NEET Biology with Water Pollution MCQ practice. Find answers and study Water Pollution MCQ topics.
authorImageKrati Saraswat27 May, 2025
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Water Pollution MCQ

Water pollution MCQ:  Water pollution refers to the contamination of water bodies such as lakes, rivers, oceans, and groundwater by harmful substances. This environmental issue poses a significant threat to both aquatic life and human health. Various factors contribute to water pollution, including industrial activities, agriculture practices, improper waste disposal, oil spills, and sewage discharge.

Water Pollution MCQ Introduction

Industrial processes often release toxic chemicals into nearby water sources through direct effluent discharge or accidental leaks. Likewise, agricultural runoff carries fertilizers and pesticides into streams and lakes during heavy rainfall or irrigation periods. These pollutants not only disrupt the delicate balance of ecosystems but also introduce hazardous contaminants into the food chain as they accumulate in fish and other organisms consumed by humans. Furthermore, untreated sewage being discharged directly into natural bodies of water can spread disease-causing microorganisms leading to widespread illness among those who rely on contaminated water for drinking or cooking purposes. Consequently, combating this grave issue requires a collective effort from individuals and industries alike to adopt sustainable practices that minimize their impact on water resources while ensuring a clean supply for future generations.

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Water Pollution MCQ

Q.1 High concentrations of accumulated DDT in birds

  1. kills pathogens in their blood
  2. causes sterility by affecting gametogenesis
  3. leads to the premature breaking of eggs
  4. causes spasticity of the muscles of the body
Answer- 4, leads to premature breaking of eggs
Explanation: High concentrations of DDT in birds can cause a wide range of negative effects, from sterility to premature breaking of eggs. DDT accumulates in the birds' bodies and kills pathogens in their blood, which can interfere with gametogenesis, leading to sterility. It can also lead to spasticity of the muscles of the body, thus affecting the bird's ability to fly correctly. In order to prevent these effects, it is important to reduce or eliminate the use of DDT in areas where it is used agriculturally.

 Q 2. Eutrophication is often seen in

  1. freshwater lakes
  2. Ocean
  3. mountains
  4. Deserts
Answer- 4, freshwater lakes
Explanation: Eutrophication is most commonly seen in freshwater lakes. It is a process characterized by excessive nutrient enrichment, particularly of phosphorus and nitrogen, in a body of water. This enrichment can occur due to various factors such as agricultural runoff, sewage discharge, and the use of fertilizers. When these nutrients enter a lake, they stimulate the growth of algae and other aquatic plants. As a result, an excessive amount of plant biomass is produced, leading to a phenomenon known as algal blooms.

Q 3. The natural ageing of a lake by biological enrichment is known as:

  1. Eutrophication
  2. Biomagnification
  3. Bioremediation
  4. Biofortification
Answer- 1, Eutrophication
Explanation: Eutrophication. Eutrophication is a natural aging process where a body of water becomes enriched with nutrients, leading to an increase in biological activity in the ecosystem. These biological activities can have both positive and negative effects on the environment, depending on the type and amount of nutrients present.

Q 4. Examples of integrated wastewater treatment include

  1. Biologists at the town of Arcata and Humboldt State University on California's North Shore
  2. A biologist at Bangalore City and Humboldt State University
  3. A biologist at New York City and Purdue University on California's North Coast
  4. The town of Arcata on California's North Shore and Purdue University of Biologists
Answer- a Biologists at the town of Arcata and Humboldt State University on California's North Shore
Explanation: The town of Arcata along the northern coast of California and biologists from Humboldt State University developed an integrated wastewater treatment system. This system consists of a three-stage process that involves treated wastewater being discharged into the ocean. First, the wastewater is screened for large debris and solids, then it is filtered using a sand filtration system. After this, the water goes through a disinfection process that uses ultraviolet light or chlorine to kill disease-causing organisms. Finally, the treated water is released back into the ocean via an outfall pipe. This type of technique provides a great example of how natural systems can be used in combination with technology to effectively reduce water pollution.

Q 5. The natural aging of a lake

  1. Depends on climate
  2. Depends on the size of the lake
  3. May take thousands of years
  4. All of these
Answer- 4, All of these
Explanation: The natural aging of a lake is dependent on the climate it's in, the size of the lake, and other factors such as water pollution. It can take thousands of years for a lake to age naturally, so it's important to be aware of any changes that may occur in order to keep it healthy.

Q 6. Photo Electro Chemical (PEC) solar cells are based on

  1. Only inorganic semiconductors
  2. Only organic semiconductors
  3. Only crystal silicon semiconductor
  4. Electrolyte and inorganic semiconductor hybrid structure
Answer- d, Electrolyte and inorganic semiconductor hybrid structure Explanation: Hybrid structure of inorganic semiconductors and an electrolyte. PEC solar cells are based on a hybrid structure composed of an inorganic semiconductor such as titanium dioxide (TiO2), dye-sensitized TiO2, or zinc oxide (ZnO) nanostructures, and a liquid electrolyte. These compounds absorb solar radiation and generate free electrons by the photovoltaic effect. The electrons move from the semiconductor to the electrolyte, producing an electric current.

Q 7. Photoelectrochemical decomposition of water is done to

  1. To produce hydrogen
  2. To remove pathogens from water
  3. To remove metals from water
  4. To remove oil and grease from water
Answer- c, To remove metals from water
Explanation: Photo-electro-chemical decomposition of water is an effective and efficient way to remove metals from water. It works by using light energy to break down molecules into simpler forms and can be used to remove metals, oil, grease, and other pathogens from water. This process makes the water clean and safe for consumption while minimizing environmental impact.

Q 9. Which of the following substances is not a water pollutant?

  1. Chromium
  2. Silt
  3. Glacier
  4. Arsenic
Answer- c, Glacier
Explanation: Glacier. Glacier is not considered water pollutant, as glaciers are large masses of ice and snow formed over thousands of years that can slowly move downhill under gravity's influence. Water pollution occurs when toxic substances contaminate rivers, lakes, oceans, and other water sources through human activities such as industrial waste, runoff from agriculture, or oil spills. Common water pollutants include arsenic, chromium, silt, and nitrates.

Q 10. Streams draining into the lake introduce nutrients such as .... (Young Lake)

  1. Nitrogen and Phosphorus
  2. DDT and cadmium
  3. DDT
  4. Calcium
Answer- Nitrogen and Phosphorus
Explanation: Nitrogen and Phosphorus. Nitrogen and phosphorus are commonly found in agricultural fertilizers, sewage effluent, and urban runoff that can flow into streams leading to a lake. These nutrients can cause algae blooms and deplete oxygen levels in the water, making it difficult for other aquatic life to survive.

Q 11. There was a significant decline in bird populations in an area where DDT had been extensively used because

  1. Birds stopped laying eggs
  2. Earthworms in the area got eradicated
  3. Cobras were feeding exclusively on birds
  4. Birds laid eggs and the eggs hatched early
Answer- birds stopped laying eggs
Explanation: DDT is a chemical that can be harmful to the environment and animals, including birds. In an area where it had been used extensively, this caused significant changes to the bird population. This was because the chemical caused the eggs to not hatch properly, which led to fewer birds being born, and also eliminated earthworms in the area that birds rely on as a food source. Additionally, some cobras started to feed exclusively on birds, further reducing their population numbers.

Q 12. In rivers with domestic sewage rich in organic waste, the following may happen

  1. increased population of aquatic food web organisms
  2. an increased production of fish due to biodegradable nutrients
  3. death of fish due to lack of oxygen
  4. Algal blooms will cause the river to dry very soon
Answer- c, death of fish due to lack of oxygen
Explanation: When organic matter from domestic sewage enters a river, it undergoes decomposition which requires oxygen and depletes the dissolved oxygen in the water. When there is not enough oxygen present, most aquatic organisms will die or have difficulty surviving. This may result in a phenomenon known as eutrophication, where high levels of nutrients lead to an algal bloom that can lead to further depletion of oxygen.

Q 13. Which of the following is not associated with Eco-san toilets?

  1. Are working in Sri Lanka and Kerala
  2. Composting method for recycling of human excreta
  3. Recycled material forms natural fertilizer
  4. Enhance the need for chemical fertilizers
Answer- d, Enhance the need for chemical fertilizers
Eexplanation: Enhance the need for chemical fertilizers. Eco-san toilets are a form of composting toilet which is a dry-tech, waterless, sanitation system that uses no water to process and dispose of human excreta. This method helps recycle waste materials into natural fertilizer while reducing the need for chemical fertilizers. It has been implemented in several countries including Sri Lanka and Kerala.

Q 14. The formation of London smog takes place in

  1. Winter during night time
  2. Summer during daytime
  3. Summer during the morning time
  4. Winter during morning time
Answer- d, Winter during morning time
Explanation: London smog is most likely to form in the winter during the day time. This is due to colder temperatures and low wind speeds, which create an inversion layer that traps pollutants near the ground. This makes it more difficult for pollutants to disperse, leading to increased levels of air pollution.

Q 15. If the lake is covered with algae, it will smell bad and the water will be undrinkable. Here's why the lake got into this state:

  1. Eutrophication.
  2. Excess of oxalate ions in water.
  3. Excess of non-biodegradable waste in water.
  4. Excess of photosynthesis.
Answer- a, Eutrophication
Explanation: Eutrophication. This occurs when excess nutrients, such as phosphorus and nitrogen, are released into the water. These nutrients encourage the growth of algae which can lead to an increase in water turbidity, a decrease in oxygen levels, and an increase in toxic compounds in the water. This can make the lake's water become unusable for humans or animals.

Check More Important NEET Biology MCQ

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