Selina Concise Solutions for ICSE Class 10 Biology Chapter 14 Pollution A Rising Environmental Problems

Exercise 1

Solution A.1.
Answer: (d) The dust raised during road-cleaning
In simple words: When roads are cleaned, dust particles get mixed with air and pollute it, making the air dirty to breathe.

📝 Teacher's Note: Show students real examples of dust pollution during road cleaning or construction work. This visual connection helps them understand air pollution sources in their daily environment.

🎯 Exam Tip: Focus on identifying pollution sources in everyday activities - road cleaning creates particulate matter that pollutes air.

Solution A.2.
Answer: (b) Disposing of corpses in rivers
In simple words: When dead bodies are put in rivers, they release harmful bacteria and chemicals that make the water unsafe for drinking and swimming.

📝 Teacher's Note: Discuss cultural practices sensitively while emphasizing environmental impact. Explain how decomposition releases pathogens and depletes oxygen in water bodies.

🎯 Exam Tip: Remember that biological waste disposal in water bodies causes severe water pollution through pathogenic contamination.

Solution A.3.
Answer: (b) Ozone
In simple words: Ozone acts like Earth's sunscreen in the upper atmosphere, protecting us from harmful sun rays that can cause skin cancer.

📝 Teacher's Note: Clarify the difference between good ozone (stratospheric) and bad ozone (ground level). Use the sunscreen analogy to make the protective function memorable.

🎯 Exam Tip: Distinguish between ozone as a pollutant at ground level and as a protective layer in the stratosphere.

Solution B.1.
Answer:
(i) \( SO_2 \)
(ii) Bromochlorodifluoromethane and chlorofluoromethane
(iii) Mercury
In simple words: These are specific chemical pollutants - sulfur dioxide from burning fuel, CFCs from old refrigerators, and mercury from industrial waste.

📝 Teacher's Note: Connect these chemicals to their common sources - SO2 from vehicle exhaust, CFCs from old cooling systems, mercury from thermometers and industrial processes.

🎯 Exam Tip: Learn the chemical formulas and sources of major pollutants - this knowledge appears frequently in environmental science questions.

Solution B.2.
Answer:

In simple words: Each pollutant causes a specific type of environmental problem - like CFCs making holes in the ozone layer that protects us from sun's harmful rays.

📝 Teacher's Note: Use cause-effect relationships to help students remember these matches. Create simple mnemonics like "CFCs Cut ozone" or "SO2 makes Sour rain."

🎯 Exam Tip: Learn the specific environmental effects of each pollutant - matching questions often test these cause-effect relationships.

Solution B.3.
Answer:
(i) vehicular air
(ii) X-ray
(iii) hot
(iv) domestic activities
In simple words: These are fill-in-the-blank answers about pollution sources - cars pollute air, X-rays create radiation, hot water causes thermal pollution, and household activities create waste.

📝 Teacher's Note: Connect each answer to students' daily experiences - vehicle exhaust they see on roads, X-rays at hospitals, hot water from factories, kitchen waste at home.

🎯 Exam Tip: Pay attention to context clues in fill-in-the-blank questions to identify the type of pollution being discussed.

Solution C.1.
Answer:

(i) Rivers contaminated with sewage:
• A number of waterborne diseases are produced by the pathogens present in polluted water, affecting humans as well as animals.
• The flora and fauna of rivers, sea and oceans is adversely affected.

(ii) Too much gaseous exhausts containing \( CO_2 \) and \( SO_2 \):
• The high concentration of \( CO_2 \) in atmosphere has been the main component of the green house effect that has caused global warming i.e. the rise of atmospheric temperature in recent years. Global warming causes melting of snow caps rise in sea levels.
• \( SO_2 \) is poisonous and irritates the respiratory system of animals and humans. A continuous exposure to \( SO_2 \) has been reported to damage the lungs and increase the rate of mortality.
• \( SO_2 \) is also responsible for acid rain

(iii) Pesticides such as DDT used in agriculture:
• Pesticides kill soil microbes which are responsible to recycle the nutrients in the soil.
• Pesticides can enter the food chain and affect the health of humans as well as animals. It can cause damage to the lungs and central nervous system, failures of reproductive organs and dysfunctions of the immune system, endocrine system, and exocrine system, as well as potential cancer risks and birth defects.

(iv) Prolonged noise such as the one produced by crackers throughout night:
• Prolonged exposure to the high decibel noise damages ear drums and can bring permanent hearing impairment.
• Noise pollution can lead to high blood pressure (hypertension), constant headache, lack of concentration.

In simple words: These pollution sources harm the environment in different ways - sewage spreads diseases, gases cause global warming and acid rain, pesticides poison the food chain, and loud noise damages our hearing and health.

📝 Teacher's Note: Use local examples for each type of pollution. Discuss how sewage treatment works, show effects of acid rain on buildings, explain bioaccumulation of pesticides, and demonstrate noise levels with a decibel meter.

🎯 Exam Tip: For descriptive answers, always mention both immediate effects (like diseases) and long-term consequences (like global warming) of each pollution type.

Solution C.2.
Answer:
Three major constituents of sewage:
1. Kitchen wastes
2. Sanitary waste
3. Waste from agricultural lands
In simple words: Sewage is made up of waste water from our kitchens, toilets, and farms - basically all the dirty water that goes down drains.

📝 Teacher's Note: Trace the journey of waste water from homes to treatment plants. Show students where their household waste water goes and how it gets cleaned.

🎯 Exam Tip: Remember the three main sources of sewage - domestic (kitchen + sanitary) and agricultural waste water.

Solution C.3.
Answer:
• The common sources of oil spills are: The overturned oil tankers, offshore oil mining and Oil Refineries.
• The sea birds and sea animals sometimes get thick, greasy coating on their bodies due to oil spills.
• Sea birds may ingest their oil coated. This may irritate their digestive system, may damage liver and kidney.
• Oil spills lead to the death of sea birds as well as sea animals.
In simple words: When oil ships crash or oil wells leak, the oil spreads in water and coats sea animals with a thick, sticky layer that makes them sick and often kills them.

📝 Teacher's Note: Show images of oil-covered birds from real spill incidents. Explain why oil and water don't mix and how this makes cleanup difficult. Discuss cleanup methods like dispersants.

🎯 Exam Tip: Focus on both sources of oil spills and their effects on marine life - especially the physical coating and internal damage to animals.

Solution C.4.
Answer:
Measures to minimise noise pollution:
1. Use of loud speakers should be banned.
2. Airports should be located away from the residential area.
In simple words: To reduce noise pollution, we should ban loud speakers and build noisy places like airports far away from where people live.

📝 Teacher's Note: Discuss additional measures like sound barriers, noise limits during night hours, and personal protective equipment. Relate to local noise regulations and enforcement.

🎯 Exam Tip: Focus on practical solutions that either reduce noise at source or separate noise sources from populated areas.

Solution D.1.
Answer:
1. Industrial Waste:
Large number of industries produces waste water which contains various types of chemical pollutants. Such wastes are commonly discharged into the rivers. These chemicals cause irritation to the body systems of fish.

2. Thermal Pollution:
Many industries such as thermal power plants, oil refineries, nuclear plants use water for cooling their machinery. This hot waste water may be 8-10°C warmer than the intake water. This hot water is released into the nearby streams, rivers or the sea and causes warming. The sudden fluctuation in the temperature of water kills the fishes and harms the plant life growing in it.
In simple words: Factories pollute water in two ways - by adding harmful chemicals and by releasing hot water that's too warm for fish and plants to survive.

📝 Teacher's Note: Demonstrate temperature sensitivity of aquatic life using simple experiments. Show how even small temperature changes affect fish behavior. Discuss thermal pollution near local power plants.

🎯 Exam Tip: Distinguish between chemical pollution (toxic substances) and thermal pollution (temperature change) - both are industrial water pollution but have different mechanisms.

Solution D.2.
Answer:
(i) Noise Pollution
(ii) Industrial machines, workshops, trains, loud conversation, loudspeakers, etc.
(iii) Effects of noise pollution:
1. It lowers efficiency of work.
2. It disturbs sleep and leads to nervous irritability.
In simple words: Noise pollution comes from loud machines and sounds, making it hard to work properly, sleep well, and stay calm.

📝 Teacher's Note: Measure noise levels in different environments using smartphone apps. Help students understand decibel scales and safe exposure limits for various sound levels.

🎯 Exam Tip: Remember both sources of noise pollution and its effects on human health and productivity - questions often ask for both aspects.