Biology Questions and Answers – Environmental Issues – Water Pollution and its Control – 1

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This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Environmental Issues – Water Pollution and its Control – 1”.

1. When the government of India did pass the Water (Prevention and Control of Pollution) Act?
a) 1999
b) 1974
c) 1896
d) 2010
View Answer

Answer: b
Explanation: In 1974, the Water (Prevention and Control of Pollution) Act was passed by the government of India. It is comprehensive legislation for maintaining or restoring of wholesomeness of water by prevention and control of the pollution of water.
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2. How much percent of impurities are enough to make domestic sewage unfit for humans?
a) 0.1 percent
b) 1 percent
c) 5 percent
d) 10 percent
View Answer

Answer: a
Explanation: To make domestic sewage unfit for humans 0.1 percent of impurities are enough. These 0.1 percent impurities contain dissolved materials (ammonia, nitrate, sodium, etc.), colloidal materials (bacteria, cloth, fecal matter, etc.) and suspended solids (clay, sand, and silt).

3. Which of the following are the suspended solids in the domestic sewage?
a) Ammonia
b) Sand
c) Calcium
d) Bacteria
View Answer

Answer: b
Explanation: The suspended solids like sand, clay, and silt are commonly found in domestic sewage. They are the impurities that are visible and do not dissolve in water. They can be removed easily by physical or mechanical means.
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4. Which of the following are the colloidal materials present in domestic sewage?
a) Calcium
b) Sand
c) Ammonia
d) Fecal matter
View Answer

Answer: d
Explanation: The substances that do not readily dissolve in water but also are not settled down are known as colloidal substances. They may be filtered out in a Gooch Crucible and contains fecal matter, bacteria, cloth, and paper fibers.

5. Which of the following are the dissolved materials present in domestic sewage?
a) Sand
b) Clay
c) Nutrients
d) Bacteria
View Answer

Answer: c
Explanation: These are the smaller size particles that can easily pass through all the filters hence said as dissolved materials. They contain various nutrients like ammonia, calcium, nitrate, phosphate, and sodium.
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6. Which materials are easily removed from the polluted water?
a) Liquid
b) Solids
c) Dissolved
d) Nutrients
View Answer

Answer: b
Explanation: The large-sized solid materials can be easily removed from the polluted water by physical or mechanical means. These can be plastics, metals, sand, etc.

7. Which materials are hard to remove from the polluted water?
a) Sand
b) Plastic
c) Solids
d) Dissolved salts
View Answer

Answer: d
Explanation: The smaller sized dissolved materials are hard to remove from domestic sewage water as they can pass through the filters easily. They contain nutrients such as ammonia, calcium, nitrate, phosphate, and sodium.
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8. Which sewage contains biodegradable waste such as organic matter?
a) Medical waste
b) Plastic waste
c) Domestic waste
d) Wild waste
View Answer

Answer: c
Explanation: The biodegradable organic matter is a component of domestic sewage. The organic compounds present in domestic wastewater are carbohydrates, proteins, and fats (containing carbon, hydrogen, oxygen, nitrogen, sulphur, phosphorus, etc.).

9. Who is responsible for the degradation of biodegradable organic matter present in the domestic sewage?
a) Animals
b) Humans
c) Plastic
d) Bacteria and other microbes
View Answer

Answer: d
Explanation: The degradation of biodegradable organic matter present in the domestic sewage is done by microbes. They degrade this organic matter and uptake the essential nutrients required for their growth and development.
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10. How is the amount of biodegradable organic matter in sewage water estimated?
a) Chemical Oxygen Demand
b) Physical Oxygen Demand
c) Biological Oxygen Demand
d) Mathematical Oxygen Demand
View Answer

Answer: c
Explanation: The amount of biodegradable organic matter in sewage water estimated with the help of biological oxygen demand. It is used for indicating the organic strength of wastewater. It is designated as BOD.

11. Who utilizes the maximum amount of oxygen in the upstream of sewage discharge?
a) Animals
b) Microorganisms
c) Humans
d) Plants
View Answer

Answer: b
Explanation: In the upstream of sewage water, the maximum oxygen is used by the microorganisms. Due to this, there is less oxygen availability in the downstream that is rivers, ponds, or the other water bodies where the fully processed wastewater is released.

12. What happens when the maximum amount of oxygen in the upstream of sewage discharge is utilized by microbes?
a) Natality of aquatic plants
b) Natality of aquatic fishes
c) Mortality of aquatic creatures
d) Mortality of bacteria
View Answer

Answer: c
Explanation: When the maximum amount of oxygen in the upstream of sewage discharge is utilized by microbes, there is less oxygen availability in the downstream that is rivers, ponds, or the other water bodies. Due to this, the aquatic organisms living in that respective ecosystem die due to a deficiency of oxygen.

13. What is the excess growth of plankton in water due to the presence of nutrients called?
a) Fungal bloom
b) Algal bloom
c) Plantae bloom
d) Animal bloom
View Answer

Answer: b
Explanation: The excessive growth of planktons in any water body due to the presence of nutrients is known as an algal bloom. An algal bloom or marine bloom or water bloom is a rapid increase of algae in an aquatic system (freshwater as well as marine water).

14. Which of the following is the effect of high BOD?
a) More birth of aquatic plants
b) More birth of fishes
c) Higher dissolved oxygen
d) Lower dissolved oxygen
View Answer

Answer: d
Explanation: The high BOD results in the reduction of dissolved oxygen in the water. This is because the maximum amount of oxygen is utilized by microbes in decomposing the organic wastes of water.

15. What do BOD and COD stand for?
a) Biological Oxygen Demand and Chemical Oxygen Demand respectively
b) Chemical Oxygen Demand and Biological Oxygen Demand respectively
c) Botanical Oxygen Demand and Chemical Oxygen Demand respectively
d) Basic Oxygen Demand and Chemical Oxygen Demand respectively
View Answer

Answer: a
Explanation: The BOD and COD stand for the Biological Oxygen Demand and Chemical Oxygen Demand respectively. BOD is the dissolved oxygen is utilized by microbes in decomposing the organic wastes of water while COD is the measure of the amount of oxygen necessary to oxidize all the pollutants present in water.

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