Q31. Eutrophication of water bodies is predominantly caused by an excess of:
Environmental and Ecological Changes and Impact Assessment: RAS Prelims MCQs
168 RAS Prelims MCQs on environmental and ecological changes and impact assessment cover ecosystem concepts, pollution, climate and environmental law. Ecotones, decomposers, primary productivity, secondary pollutants, the greenhouse effect, the EIA Notification 2006, the Environment (Protection) Act 1986 and the Aravalli mining ban are asked as definitions, laws and statements.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Showing 31–40 of 168 questions
Q32. Biochemical Oxygen Demand (BOD) is a measure of:
Explanation
Scientists use a specific test to determine the level of organic pollution in a water sample. This measure quantifies the amount of dissolved oxygen required by microorganisms to break down the organic material present over a set period. A high value indicates that the water is heavily contaminated with waste, as more oxygen is needed for the bacteria to complete the decomposition.
Q33. Minamata disease is a neurological syndrome caused by severe poisoning of:
Explanation
A severe neurological condition first discovered in a coastal Japanese town was linked to the industrial discharge of a toxic heavy metal into the local bay. The chemical transformed into an organic form that accumulated in fish and shellfish. People who consumed the contaminated seafood suffered from symptoms like loss of coordination and muscle weakness, illustrating the dangers of mercury in the environment.
Q34. What is the primary purpose of the ‘Activated Sludge Process’ in wastewater treatment?
Explanation
During the treatment of wastewater, a biological stage is used to break down dissolved and suspended organic matter. This process involves mixing the water with a concentrated population of bacteria and other microorganisms in an aerated tank.
Q35. High concentrations of fluoride in drinking water cause which of the following conditions?
Explanation
While small amounts of a certain mineral can help prevent tooth decay, excessive intake through drinking water over a long period causes serious health problems. The most severe form of this condition affects the bones, leading to pain and permanent deformities. This issue is particularly prevalent in regions where the groundwater naturally contains high concentrations of the mineral due to local geological formations.
Q36. Which of the following correctly pairs a water pollutant with its associated health effect?
Explanation
Different chemical contaminants in water are linked to specific medical conditions. For example, high levels of a particular nitrogen compound are known to interfere with the blood’s ability to carry oxygen, especially in infants. This condition, often caused by runoff from fertilized fields, results in a characteristic bluish tint to the skin and can be life-threatening if the exposure is not stopped.
Q37. Match List I with List II regarding wastewater treatment:
| Wastewater Treatment Stage | Associated Process |
|---|---|
| A. Primary Treatment | i. Biological degradation of organic matter |
| B. Secondary Treatment | ii. Chlorination or UV radiation |
| C. Tertiary Treatment | iii. Physical settling and screening |
| D. Disinfection | iv. Advanced nutrient and chemical removal |
Explanation
Cleaning wastewater involves several distinct steps. The initial phase uses physical methods like screening and settling to remove large solids. The next stage employs biological processes where microorganisms digest dissolved organic matter. More advanced techniques are then used to target specific nutrients and chemicals. Finally, the water is treated with chemicals or radiation to kill any remaining harmful bacteria before it is reused.
Q38. The ‘Ganga Action Plan’ in India was launched primarily to:
Explanation
A major national initiative was launched to address the severe pollution in one of the world’s most significant rivers. The primary objective was to improve the quality of the water by reducing the amount of untreated domestic and industrial waste being discharged. This was achieved through the construction of numerous sewage treatment plants and the diversion of sewage away from the main river.
Q39. The presence of coliform bacteria in a water sample indicates:
Explanation
Testing for a specific group of microorganisms that are naturally found in the intestines of warm-blooded animals is a standard way to assess water safety. Their presence in a sample serves as a clear warning that the water has been contaminated with waste from humans or animals. This indicator suggests that dangerous pathogens could also be present, making the water unsafe for drinking.
Q40. Bioremediation is defined as:
Explanation
Cleaning up contaminated environments can be achieved through a technology that uses the natural metabolism of living organisms. These biological agents, such as bacteria or fungi, are introduced to break down or neutralize hazardous substances in the soil or water. This method is often preferred over traditional chemical or physical cleaning because it is more cost-effective and has a lower environmental impact.Answer key for these questions
| Q | Correct answer |
|---|---|
| 31 | (d) Nitrogen and Phosphorus |
| 32 | (c) Oxygen needed by bacteria for decomposition |
| 33 | (b) Methylmercury |
| 34 | (d) Secondary treatment to reduce organic matter |
| 35 | (a) Skeletal fluorosis |
| 36 | (c) Nitrate - Methemoglobinemia |
| 37 | (a) A-iii, B-i, C-iv, D-ii |
| 38 | (d) Improve water quality via sewage treatment |
| 39 | (b) Fecal contamination |
| 40 | (d) Use of living organisms to degrade contaminants |
Key facts from Environmental and Ecological Changes and Impact Assessment
- An ecosystem is made of interacting organisms and their physical environment; an ecotone is a zone of transition between ecosystems.
- Saprotrophs convert complex organic matter into simple substances; gross primary productivity is the rate at which producers create organic matter.
- Plants release water vapour through transpiration.
- Ground-level ozone is a secondary pollutant; CO, SO₂ and PM10 are primary pollutants.
- The greenhouse effect is the trapping of heat by atmospheric gases.
- Category B2 projects are exempt from public consultation under the EIA Notification 2006; the Supreme Court banned mining in the Aravalli range in Haryana and Rajasthan.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Environmental and Ecological Changes and Impact Assessment?
This page has 168 practice MCQs on Environmental and Ecological Changes and Impact Assessment (Health, Environment and Agriculture). Each has the correct answer, and most have an explanation.
What is a secondary pollutant?
A pollutant that is not emitted directly but forms in the air from primary pollutants. Ground-level ozone is the standard example, formed when nitrogen oxides and volatile organic compounds react in sunlight.
What is an ecotone?
A zone of transition between two different ecosystems, such as the area between a forest and a grassland. It often has more species than either neighbour because it has species of both.
Which projects are exempt from public consultation under EIA 2006?
Category B2 projects, which have less environmental impact. Category A and B1 projects need public consultation as part of the clearance process, which is the main way local people are heard.