Environment — Important Questions

Carbon dioxide levels would rise and oxygen levels would fall, worsening air quality

Step 1: In the oxygen cycle, plants absorb carbon dioxide during the day through photosynthesis and release oxygen. Step 2: When trees are cut down, this natural process of CO₂ absorption stops, causing CO₂ to accumulate in the atmosphere. Step 3: Simultaneously, the production of fresh oxygen decreases since fewer plants are performing photosynthesis. Step 4: This imbalance worsens air quality, contributes to global warming and makes it difficult to breathe — directly linking deforestation to air pollution. Step 5: Option B is scientifically incorrect — fewer trees means less oxygen, not more

Chemical pollutants reduce the dissolved oxygen in water, suffocating the fish

Step 1: Fish, like all living beings, require oxygen to survive — they breathe dissolved oxygen present in water through their gills. Step 2: When chemical waste from factories enters water bodies, it triggers excessive growth of algae and microbes that consume most of the dissolved oxygen. Step 3: Additionally, some chemicals directly react with and deplete the dissolved oxygen in water. Step 4: With reduced oxygen levels, fish are unable to breathe and eventually die — a process known as eutrophication-related oxygen depletion. Step 5: Option B is factually wrong — chemical pollutants may ra

Smog contains chemical pollutants that cause respiratory diseases and reduces visibility more severely than ordinary fog

Step 1: Ordinary fog is formed from water droplets suspended in air and is generally harmless. Step 2: Smog, however, is a mixture of smoke particles and fog — it contains harmful chemicals, carbon particles, and toxic gases from vehicles and industries. Step 3: When inhaled, these chemical pollutants damage the respiratory tract, causing diseases like bronchitis and asthma. Step 4: Smog also reduces visibility more severely than plain fog, causing accidents on roads — this is explicitly mentioned in the chapter. Step 5: Option B confuses smog with fog by focusing only on water content. Option

Germs from defecation and garbage in soil entered through the skin on his feet

Step 1: The chapter directly narrates Ramesh's son's case, where the doctor confirmed the stomach disorder was due to walking barefoot on soil. Step 2: Open defecation and urination on soil introduce disease germs and worms (like hookworms) into the soil. Step 3: When a person walks barefoot, these germs and worms penetrate the skin through the feet and enter the bloodstream, eventually reaching the digestive system. Step 4: This is a well-known mode of transmission for soil-transmitted helminths (worms) like hookworm — a direct link between soil pollution and human health. Step 5: Option B de