Ready for Environment and Ecology Test 5? 🌱 This TNPSC Biology quiz focuses on Environmental Pollution and Waste Management. Try the questions, check your answers, and see how well you know these important topics.
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Note: After completing the test, review the detailed explanations below to reinforce your knowledge and identify areas that need more attention.
TNPSC Biology Environment & Ecology – Test 5 – Topic Overview & Quick Revision
This section explains the answers from Environment and Ecology Test 5 with a focus on important TNPSC Biology topics such as Environmental Pollution and its different types, including air, water, soil, noise, thermal, and radioactive pollution.
It also covers Waste Management topics such as biodegradable and non-biodegradable waste, solid waste, plastic pollution, e-waste, sewage treatment, composting, and the Reduce, Reuse, Recycle approach. Read each explanation carefully to understand the topic and strengthen your TNPSC Biology preparation.
1. Environmental pollution is best described as
Answer: B. Undesirable change in environmental quality
Explanation : Environmental pollution refers to an undesirable change in the physical, chemical, or biological characteristics of the environment that can adversely affect living organisms and environmental quality. Pollution may affect different environmental components such as air, water, and soil.
Real-Life Example:
Smoke and harmful gases released from vehicles can reduce air quality and contribute to air pollution. Similarly, untreated sewage released into a river can reduce water quality and harm aquatic life.
Why Other Options Are Wrong
- A. Natural variation in climate — Natural climate variations are not, by themselves, considered environmental pollution.
- C. Seasonal movement of organisms — Migration of birds or animals is a natural ecological process, not pollution.
- D. Natural recycling of nutrients — Nutrient cycling is an essential natural process that helps maintain ecosystem balance.
2. Which of the following is a primary air pollutant?
Answer: C. Sulfur dioxide
Explanation : Primary air pollutants are pollutants that are released directly into the atmosphere from natural or human-made sources. Sulfur dioxide (SO₂) is a primary air pollutant, mainly released during the burning of sulfur-containing fossil fuels and from certain industrial processes. In contrast, ozone and PAN are secondary pollutants, formed through chemical reactions in the atmosphere, particularly in the presence of sunlight. Photochemical smog is also a secondary atmospheric phenomenon. TNPSC’s Environmental Science syllabus specifically includes primary and secondary pollutants, SO₂, PAN and photochemical smog.
Real-Life Example:
Burning coal or other sulfur-containing fuels in industries and thermal power plants can release sulfur dioxide directly into the air.
Why Other Options Are Wrong
- A. Ozone — Ground-level ozone is a secondary pollutant formed through atmospheric reactions involving nitrogen oxides and volatile organic compounds in sunlight.
- B. PAN — Peroxyacetyl nitrate (PAN) is a secondary pollutant associated with photochemical smog.
- D. Photochemical smog — It forms through chemical reactions between pollutants in sunlight and is therefore considered secondary.
3. Which gas is mainly associated with acid rain?
Answer: B. Sulfur dioxide
Explanation : Sulfur dioxide (SO₂) is one of the major gases responsible for acid rain. It is released mainly from the burning of coal and other sulfur-containing fossil fuels and from certain industrial activities. In the atmosphere, sulfur dioxide undergoes chemical reactions and forms sulfuric acid, which can contribute to the acidity of rainwater.
Real-Life Example:
Emissions from coal-based thermal power plants can release sulfur dioxide into the atmosphere. The resulting acidic compounds may reach the ground through rain and affect soil, water bodies, vegetation, and buildings.
Why Other Options Are Wrong
- A. Oxygen — Oxygen is an essential component of the atmosphere but is not a major cause of acid rain.
- C. Hydrogen — Hydrogen is not a major atmospheric gas responsible for acid rain.
- D. Helium — Helium is an inert gas and does not contribute significantly to acid rain.
4. Excessive growth of algae in a water body due to nutrient enrichment is called
Answer: A. Eutrophication
Explanation : Eutrophication is the enrichment of a water body with nutrients, particularly nitrogen and phosphorus, which can cause excessive growth of algae and aquatic plants. When the excess algae die and decompose, microorganisms consume dissolved oxygen, which can reduce oxygen availability for aquatic organisms.
Real-Life Example:
Fertilizers washed from agricultural fields into ponds or lakes can add excess nutrients to the water and encourage algal growth.
Why Other Options Are Wrong
- B. Biomagnification — It refers to the increase in concentration of certain persistent pollutants as they move through successive levels of a food chain.
- C. Sedimentation — It is the settling and accumulation of suspended particles at the bottom of a water body.
- D. Desalination — It is the process of removing dissolved salts from saline water.
5. Which parameter indicates the amount of oxygen required by microorganisms to decompose organic matter in water?
Answer: A. BOD
Explanation : Biochemical Oxygen Demand (BOD) indicates the amount of dissolved oxygen required by microorganisms to break down biodegradable organic matter present in water. A higher BOD generally indicates a greater amount of biodegradable organic matter and greater oxygen demand in the water.
Real-Life Example:
Untreated sewage entering a river contains considerable organic matter. Microorganisms decompose this material and consume dissolved oxygen, increasing the BOD of the water.
Why Other Options Are Wrong
- B. pH — It indicates how acidic or alkaline the water is.
- C. TDS — Total Dissolved Solids measure the amount of dissolved substances present in water.
- D. DO — Dissolved Oxygen (DO) is the amount of oxygen actually present in the water, whereas BOD measures the oxygen required for decomposition.
6. Which substance is a common cause of soil pollution when used excessively in agriculture?
Answer: A. Pesticides
Explanation : Excessive use of pesticides such as insecticides, herbicides, and fungicides can contribute to soil pollution. Some pesticide residues remain in the soil for long periods and may affect soil organisms, soil fertility, and groundwater when they leach through the soil.
Real-Life Example:
Repeated and excessive pesticide application in agricultural fields can leave chemical residues in the soil and may also contaminate nearby water sources.
Why Other Options Are Wrong
- B. Oxygen – Essential for living organisms and is not a soil pollutant.
- C. Water vapour – A natural component of the atmosphere and not a common cause of soil pollution.
- D. Nitrogen gas – Naturally present in the atmosphere and is not normally considered a soil pollutant.
7. Which of the following is a common source of noise pollution?
Answer: A. Automobile traffic
Explanation: Automobile traffic is a common source of noise pollution, especially in busy cities and along major roads. Vehicle engines, horns, and heavy traffic can produce excessive sound that may disturb people and wildlife.
Real-Life Example:
Continuous honking and heavy vehicle movement near busy roads can create high noise levels and disturb nearby residents.
Why Other Options Are Wrong
- B. Photosynthesis – A biological process in plants and does not produce significant noise.
- C. Rainwater harvesting – A method of collecting and storing rainwater, not a source of noise pollution.
- D. Composting – A natural process of decomposing organic waste and is not a common source of noise pollution.
8. A major effect of thermal pollution on aquatic ecosystems is
Answer: B. Reduction in dissolved oxygen
Explanation : Thermal pollution occurs when the temperature of a water body increases due to the discharge of heated water, commonly from industries and power plants. As water temperature rises, its ability to hold dissolved oxygen (DO) decreases. This can create stress for fish and other aquatic organisms that depend on oxygen in the water.
Real-Life Example:
Hot water released from a thermal power plant into a nearby water body can raise the water temperature and reduce dissolved oxygen levels.
Why Other Options Are Wrong
- A. Increase in dissolved oxygen – Warmer water generally holds less dissolved oxygen.
- C. Increase in soil fertility – Thermal pollution primarily affects aquatic ecosystems, not soil fertility.
- D. Reduction in evaporation – Higher water temperature generally increases the rate of evaporation.
9. Which type of pollution is associated with exposure to ionizing radiation?
Answer: C. Radioactive pollution
Explanation : Radioactive pollution refers to the contamination of the environment by radioactive substances or exposure to harmful ionizing radiation. Sources can include nuclear facilities, radioactive materials used in medicine and industry, and improper disposal of radioactive waste. Excessive exposure can harm living organisms and cause biological damage.
Real-Life Example:
Improper handling or disposal of radioactive materials can expose workers and nearby environments to ionizing radiation.
Why Other Options Are Wrong
- A. Thermal pollution – Caused mainly by the discharge of excess heat into water bodies.
- B. Noise pollution – Caused by excessive or unwanted sound.
- D. Soil pollution – Involves contamination of soil by harmful chemicals, wastes, and other pollutants.
10. Which pollutant is commonly produced by incomplete combustion of fuels?
Answer: A. Carbon monoxide
Explanation :
Carbon monoxide (CO) is a major air pollutant produced when fuels do not burn completely because of insufficient oxygen. It is a colourless and odourless gas and can be harmful when inhaled because it interferes with the blood’s ability to transport oxygen.
Real-Life Example:
Incomplete combustion in vehicle engines can produce carbon monoxide, particularly when combustion conditions are inefficient.
Why Other Options Are Wrong
- B. Oxygen – Oxygen supports combustion and is not produced as a pollutant by incomplete combustion.
- C. Nitrogen – Nitrogen is a major component of air but is not the typical pollutant produced by incomplete combustion.
- D. Water vapour – Water vapour can be produced during combustion but is not the pollutant referred to in this question.
11. Which device is commonly used to remove fine particulate matter from industrial exhaust?
Answer: A. Electrostatic precipitator
Explanation: An electrostatic precipitator (ESP) is an air-pollution-control device used in industries to remove fine particulate matter from exhaust gases. It gives particles an electrical charge and attracts them towards oppositely charged collection plates, where they are collected and removed.
Real-Life Example:
Electrostatic precipitators are commonly used in thermal power plants and other industries to reduce particulate emissions from flue gases.
Why Other Options Are Wrong
- B. Catalytic converter – Mainly used in vehicles to convert harmful gaseous pollutants into less harmful substances.
- C. Septic tank – Used for treating domestic sewage and wastewater.
- D. Chlorination unit – Used mainly for disinfecting water by killing or inactivating microorganisms.
12. Which of the following is biodegradable waste?
Answer: C. Vegetable peels
Explanation: Biodegradable waste is waste that can be broken down naturally by microorganisms such as bacteria and fungi. Vegetable peels are organic waste and decompose relatively easily, returning nutrients to the environment.
Real-Life Example:
Vegetable and fruit peels from kitchens can be added to a compost pit or compost bin and converted into useful manure.
Why Other Options Are Wrong
- A. Plastic bottle – Most conventional plastics degrade very slowly.
- B. Glass bottle – Glass does not readily decompose through biological processes.
- D. Aluminium can – Aluminium is non-biodegradable, although it can be recycled.
13. Which process converts biodegradable organic waste into nutrient-rich manure?
Answer: B. Composting
Explanation : Composting is the natural decomposition of biodegradable organic waste such as vegetable peels, leaves, and other plant materials by microorganisms. Under suitable conditions, the waste is converted into compost, which can be used as a nutrient-rich soil amendment.
Real-Life Example:
Kitchen waste such as vegetable peels and garden leaves can be collected in a compost bin and converted into compost for plants.
Why Other Options Are Wrong
- A. Incineration – Involves burning waste at high temperatures.
- C. Landfilling – Involves depositing waste in designated landfill sites rather than converting it into compost.
- D. Distillation – A separation process used mainly for liquids based on differences in boiling points.
14. Which property makes most conventional plastics a major environmental concern?
Answer: C. Slow degradation
Explanation : Most conventional plastics are non-biodegradable or degrade very slowly in the natural environment. They can persist for long periods and accumulate as waste on land and in water bodies. Plastic waste can also harm animals when they ingest it or become entangled in it.
Real-Life Example:
Plastic bags and bottles discarded in streets or water bodies can remain in the environment for long periods instead of decomposing like vegetable waste.
Why Other Options Are Wrong
- A. Rapid decomposition – Rapid decomposition would reduce the persistence of plastic waste.
- B. Easy evaporation – Conventional plastics do not normally evaporate under ordinary environmental conditions.
- D. High water solubility – Most conventional plastics are not highly soluble in water.
15. Which of the following is an example of e-waste?
Answer: A. Used computer
Explanation : E-waste (electronic waste) refers to discarded electrical and electronic equipment and their components. Computers, mobile phones, televisions, printers, and other electronic devices become e-waste when they are discarded. Some e-waste may contain hazardous substances, so proper collection, recycling, and disposal are important.
Real-Life Example:
An old computer that is no longer used should be given to an authorized e-waste collection or recycling facility rather than being mixed with ordinary household waste.
Why Other Options Are Wrong
- B. Vegetable waste – Biodegradable organic waste.
- C. Dry leaves – Biodegradable garden waste.
- D. Food scraps – Biodegradable organic waste.
16. Which stage of sewage treatment primarily removes large and suspended solids?
Answer: A. Primary treatment
Explanation : Primary treatment is the initial physical stage of sewage treatment. It removes large floating materials and suspended solids mainly through processes such as screening and sedimentation. This reduces the solid load before the sewage enters further treatment stages.
Real-Life Example:
Before wastewater undergoes biological treatment, screens can remove large objects such as plastics and other solid materials.
Why Other Options Are Wrong
- B. Secondary treatment – Mainly uses biological processes to reduce biodegradable organic matter.
- C. Tertiary treatment – Provides additional treatment to remove specific pollutants and contaminants.
- D. Disinfection only – Primarily aims to reduce harmful microorganisms and is not the main stage for removing suspended solids.
17. Which of the 3Rs should be given the highest priority for reducing waste generation?
Answer: C. Reduce
Explanation : The 3Rs – Reduce, Reuse, and Recycle – are important principles of waste management. Reduce is given the highest priority because preventing unnecessary waste at the source reduces the amount of material that needs to be reused, recycled, treated, or disposed of.
Real-Life Example:
Carrying a reusable bag instead of accepting a new plastic bag every time helps reduce waste generation at the source.
Why Other Options Are Wrong
- A. Recycle – Recycling is important, but it happens after materials have already been used and discarded.
- B. Reuse – Extends the useful life of products, but reducing consumption comes before reuse.
- D. Recover – Recovery is a waste-management approach but is not one of the basic 3Rs listed in the question.
18. Which waste-management method is most suitable for biodegradable kitchen waste?
Answer: A. Composting
Explanation : Composting is a suitable method for managing biodegradable kitchen waste such as vegetable peels, fruit scraps, and other organic materials. Microorganisms break down this waste into compost, which can be used to improve soil quality.
Real-Life Example:
Vegetable peels and fruit waste from a household can be collected separately and placed in a compost bin to produce useful compost.
Why Other Options Are Wrong
- B. Open burning – Causes air pollution and is not a suitable method for managing organic kitchen waste.
- C. Plastic packaging – Plastic is generally non-biodegradable and cannot be used to manage organic waste.
- D. Metal smelting – Used for processing metals and is unrelated to biodegradable kitchen waste.
19. Fine particulate matter in polluted air can primarily affect the
Answer: A. Respiratory system
Explanation : Fine particulate matter, especially PM2.5, consists of very small particles that can enter deep into the respiratory tract when inhaled. Exposure to particulate pollution can irritate the airways and contribute to respiratory problems. Very fine particles may also enter the bloodstream after reaching the lungs.
Real-Life Example:
People living or working near areas with heavy traffic may be exposed to higher levels of particulate matter from vehicle emissions and road dust.
Why Other Options Are Wrong
- B. Skeletal system – It is not the primary system directly affected by inhaled particulate matter.
- C. Digestive system only – Particulate pollution primarily enters the body through inhalation and affects the respiratory system.
- D. Reproductive organs only – Air pollution can have wider health effects, but the respiratory system is a primary target of inhaled particulate matter.
20. Which approach is most effective for controlling pollution at its source?
Answer: B. Preventing or reducing pollutant generation
Explanation : Pollution prevention at source means reducing or eliminating the generation of pollutants before they enter the environment. This can be achieved through cleaner production methods, efficient use of resources, pollution-control technologies, and reducing unnecessary waste.
Real-Life Example:
Using cleaner fuels and improving industrial processes can reduce the amount of pollutants released into the air instead of trying to deal with them after they have already been emitted.
Why Other Options Are Wrong
- A. Increasing waste after treatment – Producing more waste does not control pollution.
- C. Diluting every pollutant with water – Dilution does not eliminate the pollutant and can transfer pollution to water bodies.
- D. Moving pollutants to another location – Relocating pollutants does not solve the underlying pollution problem.
Further Reference – Environment and Ecology
For additional reading on Environmental Pollution, Waste Management, and related environmental topics, students can refer to the relevant NCERT textbook material. This resource provides a useful foundation for understanding environmental issues and supports the concepts covered in this TNPSC Biology – Environment and Ecology quiz.
