Samacheer Kalvi Class 12 Bio Zoology Chapter 12 Environmental Issues

Higher Order Thinking Skills (HOTs) Questions

 

Question 1. Complete the following:
(a) Smoke + _____ = Smog
Answer: Fog
In simple words: This question asks you to complete a basic equation for how smog is formed. Smog is a mix of smoke and fog.

🎯 Exam Tip: Remember common environmental terms and their components, as these often appear in fill-in-the-blanks or MCQ formats.

 

Question 2. What is the unit of measuring ozone thickness?
Answer: Dobson Unit
In simple words: The thickness of the ozone layer, which protects us from harmful sun rays, is measured using a special unit called the Dobson Unit. This unit helps scientists track how much ozone is in the atmosphere.

🎯 Exam Tip: Knowing the units of measurement for various environmental parameters is important. Always link the unit to what it measures.

 

Question 3. List any four adverse effects of noise.
Answer: High blood pressure, stress-related ailments, sleep disruption, and hearing impairment are four negative effects of noise. Noise pollution can also lead to irritability and panic attacks.
In simple words: Too much noise can make your blood pressure go up, cause stress, make it hard to sleep, and damage your hearing.

🎯 Exam Tip: When listing effects, try to group them by system (e.g., cardiovascular, nervous) or type (physical, mental) for better recall and organization in your answer.

 

Question 4. Name the scientist who discovered the ozone layer
Answer: Charles Fabry and Henri Buisson
In simple words: Two scientists, Charles Fabry and Henri Buisson, were the ones who found the ozone layer. They were the first to measure it.

🎯 Exam Tip: For discovery questions, ensure you list all key individuals involved. Full names are often required to score full marks.

 

Question 1. Right to Clean Water is a fundamental right, under the Indian Constitution
(a) Article 12
(b) Article 21
(c) Article 31
(d) Article 41
Answer: (b) Article 21
In simple words: In India, the right to clean water is considered a very important basic right for everyone, included in Article 21 of the Constitution. This means every person has a right to a healthy life, which includes clean water.

🎯 Exam Tip: When answering questions related to legal articles or constitutional provisions, be precise with the article number. Article 21 is a broad article covering the right to life and personal liberty, which the judiciary has interpreted to include many other fundamental rights like clean water and a healthy environment.

 

Question 2. With which of the following, the Agenda 21′ of Rio Summit, 1992 is related to?
(a) Sustainable development
(b) Combating the consequences of population
(c) Mitigation norms of Green House Gases (GHG) emission
(d) Technology transfer mechanism to developing countries for ‘clean energy’ production
Answer: (a) Sustainable development
In simple words: Agenda 21, which came from the Rio Summit in 1992, is all about sustainable development. This means finding ways to grow and improve without using up all our resources or harming the planet for future generations.

🎯 Exam Tip: Associate key international summits with their main outcomes or declarations, such as the Rio Summit with Agenda 21 and sustainable development. These connections are frequently tested.

 

Question 3. Which among the following awards instituted by the Government of India for individuals or communities from rural areas that have shown extraordinary courage and dedication in protecting Wildlife?
(a) Indira Gandhi Paryavaran Puraskar
(b) Medini Puraskar Yojana
(c) Amrita Devi Bishnoi Award
(d) Pitambar Pant National Award
Answer: (c) Amrita Devi Bishnoi Award
In simple words: The Indian government gives the Amrita Devi Bishnoi Award to people or groups in villages who show great bravery and effort in protecting wild animals and nature. This award honors the legacy of Amrita Devi Bishnoi, who sacrificed her life to protect trees.

🎯 Exam Tip: Familiarize yourself with national environmental awards and their specific criteria. Knowing the namesake of an award often provides a clue to its purpose.

 

Question 4. The ‘thickness’ of Stratospheric Ozone layer is measured in/on:
(a) Sieverts units
(b) Dobson units
(c) Melson units
(d) Beaufort Scale
Answer: (b) Dobson units
In simple words: The ozone layer's thickness in the stratosphere, which is the layer that protects us, is measured in Dobson units. This helps scientists keep track of how much ozone is present.

🎯 Exam Tip: Units of measurement are crucial in science. Be careful not to confuse different units; for example, Sieverts are used for radiation dose, and the Beaufort scale measures wind speed.

 

Question 5. Which among the following is the most abundant Green-House-Gas (GHG) in the Earth’s atmosphere?
(a) Carbon dioxide
(b) Water Vapour
(c) Sulphur Dioxide
(d) Tropospheric Ozone
Answer: (a) Carbon dioxide
In simple words: Among the gases that trap heat in the Earth's atmosphere, carbon dioxide is the most common and plentiful. It plays a big role in the greenhouse effect.

🎯 Exam Tip: While carbon dioxide is a major greenhouse gas, water vapor is actually the most abundant. However, the question might be implicitly asking about anthropogenic (human-caused) greenhouse gases, where CO2 is dominant. If both are options, consider the context or typical textbook emphasis. The presence of water vapor is variable and has different dynamics. In this case, carbon dioxide is the intended answer for the most *significant* and *human-influenced* abundant GHG.

 

Question 6. As per 2017 statistics, the highest per capita emitter of Carbon dioxide in the world is
(a) USA
(b) China
(c) Qatar
(d) Saudi Arabia
Answer: (b) China
In simple words: According to data from 2017, China was the country that released the most carbon dioxide per person. This means, on average, each person in China contributed more to CO2 emissions than in other countries listed.

🎯 Exam Tip: Stay updated on environmental statistics, especially regarding emissions, as these figures can change and are often used in current affairs and environmental studies questions.

 

Question 7. The use of microorganism metabolism to remove pollutants such as oil spills in the water bodies is known as
(a) Sieverts units
(b) Bioremediation
(c) Biomethanation
(d) Bioreduction
Answer: (b) Bioremediation
In simple words: When tiny living things like bacteria are used to clean up pollution, for example, getting rid of oil spills in water, it is called bioremediation. These tiny helpers break down the harmful stuff.

🎯 Exam Tip: Understand the 'bio-' prefixes in environmental terms. 'Bioremediation' involves biological agents to remedy pollution, while 'biomethanation' involves microbes producing methane, and 'bioreduction' is a specific type of biological reaction.

 

Question 8. The Ozone Day is observed every year on September 16 as on this day in 1987 the _____ was signed for launching efforts to arrest the depletion of the fragile ozone layer in the stratosphere that prevents the harmful ultra-violet rays of the Sun from reaching the Earth. Fill the correct word in blank.
(a) Montreal Protocol
(b) Geneva Protocol
(c) Kyoto Protocol
(d) Nagoya Protocol
Answer: (a) Montreal Protocol
In simple words: Ozone Day, celebrated on September 16th, marks the signing of the Montreal Protocol in 1987. This important agreement started global efforts to protect the Earth's ozone layer from harmful chemicals.

🎯 Exam Tip: Connect important dates with significant environmental agreements. The Montreal Protocol is a landmark agreement for ozone layer protection, distinguishing it from other protocols like Kyoto (climate change) or Nagoya (biodiversity).

 

Question 9. Which among the following always decreases in a Food chain across tropic levels?
(a) Number
(b) Accumulated chemicals
(c) Energy
(d) Force
Answer: (c) Energy
In simple words: In a food chain, as energy moves from one level to the next (like from plants to plant-eaters), a lot of it gets lost. This means the amount of usable energy always goes down at each higher step.

🎯 Exam Tip: Recall the 10% law of energy transfer in ecological pyramids. This principle states that only about 10% of energy is transferred from one trophic level to the next, while the rest is lost, primarily as heat. This explains the decrease in energy.

 

Question 10. In the E-waste generated by the Mobile Phones, which among the following metal is most abundant?
(a) Copper
(b) Silver
(c) Palladium
(d) Gold
Answer: (a) Copper
In simple words: When mobile phones become electronic waste, copper is the metal found most often in them. It is used a lot in circuits and wires because it conducts electricity well.

🎯 Exam Tip: Be aware of the composition of common e-waste items. While precious metals like gold and silver are present, base metals like copper and aluminum are typically found in larger quantities by weight.

 

Question 11. The Hydrochlorofluorocarbons (HCFCs) are the compounds which have the following molecules:
(a) Hydrogen
(b) Carbon
(c) Chlorine
(d) Fluorine
Answer: (c) Chlorine
In simple words: Hydrochlorofluorocarbons, or HCFCs, are special compounds that always contain chlorine atoms. These chlorine atoms are what cause harm to the ozone layer.

🎯 Exam Tip: Understand the chemical components of ozone-depleting substances. The presence of chlorine (and bromine) atoms is key to their ozone-destroying potential, as seen in CFCs and HCFCs.

 

Question 12. SMOG is derived from:
(a) Smoke
(b) Fog
(c) Both A and B
(d) Only A
Answer: (c) Both A and B
In simple words: The word "smog" was created by combining two words: "smoke" and "fog." It describes a type of air pollution that looks like a mixture of the two. Smog often forms when pollutants mix with fog.

🎯 Exam Tip: Recognize compound words in scientific terminology. Many environmental terms are portmanteau words that offer clues about their meaning, like "smog" or "acid rain".

 

Question 13. Excess of fluoride in drinking water causes:
(a) Lung disease
(b) Intestinal infection
(c) Fluorosis
(d) None of the options
Answer: (c) Fluorosis
In simple words: Drinking water that has too much fluoride can lead to a health problem called fluorosis. This condition mainly affects teeth and bones, causing them to become discolored or weak.

🎯 Exam Tip: Be precise with disease names associated with specific pollutants. Each pollutant often has a unique health impact or related condition.

 

Question 14. Expand (i) CFC (ii) AQI (iii) PAN
Answer:
(i) CFC: Chlorofluorocarbons
(ii) AQI: Air Quality Index
(iii) PAN: Peroxyacetyl nitrate
In simple words: This question asks for the full names of three common environmental abbreviations. CFCs are chemicals that harm the ozone layer, AQI tells us how clean the air is, and PAN is a harmful pollutant found in smog.

🎯 Exam Tip: Memorize the full forms of important acronyms in environmental science. These are fundamental terms and are frequently tested in objective and short-answer questions.

 

Question 7. Name the famous flagship programme of Central Government launched to achieve pollution abatement and rejuvenation of River Ganga.
Answer: The main program by the Central Government to stop pollution and make the River Ganga clean again is called Namami Gange. This initiative aims to preserve the river's ecological integrity and cultural significance.
In simple words: The important government plan to clean the Ganga river is Namami Gange.

🎯 Exam Tip: Remember the full name of the program and its two main goals: pollution control and river revival.

 

Question 8. The intensity of noise is measured in..............
(a) Dobson
(b) Hertz
(c) Decibel
(d) Frequency
Answer: (c) Decibel
In simple words: Decibel is the unit we use to measure how loud a sound is.

🎯 Exam Tip: Know the correct units for common measurements like noise, ozone thickness, and frequency for MCQs.

 

Question 9. According to noise pollution rules 2000, the permissible level of noise in the commercial area is... during the day and ............. during nitght.
(a) 55 db, 65 db
(b) 65 db, 55 db
(c) 70 db, 60 db
(d) 75 db, 65 db
Answer: (b) 65 db, 55 db
In simple words: In business areas, noise should not be more than 65 dB in the day and 55 dB at night, by rules from the year 2000.

🎯 Exam Tip: Memorize specific regulatory values and their day/night distinctions for environmental standards.

 

Question 10. Which is not a physical method of wastewater treatment.
(a) Dilute and dispense
(b) Delay and decay
(c) Limit generation
(d) Limit generation
Answer: (c) Limit generation
In simple words: Making less radioactive waste is a good idea, but it's not a way to dispose of waste that is already made. Disposal means getting rid of it, like by diluting or storing it until it becomes harmless.

🎯 Exam Tip: Understand the difference between preventing waste (like limiting generation) and methods for its disposal or treatment.

 

Question 11. Match List I with List II
Answer: This question asks you to connect different types of waste with where they come from. The correct matches are: Residential waste with Batteries; Agriculture waste with Spoiled food; E-waste with Computer Mouse; and Institutional waste with Electronics. This sorting helps in proper waste management.
In simple words: Match the type of trash with its source. Residential waste includes batteries. Farms have spoiled food. E-waste means computer mice. Buildings like offices produce general electronics trash.

🎯 Exam Tip: When matching, always consider the most direct and common associations between waste categories and their sources.

 

Question 12. Which is not a method of disposal of radioactive waste.
(a) Dilute and dispense
(b) Delay and decay
(c) Limit generation
(d) Limit generation
Answer: (c) Limit generation
In simple words: Making less radioactive waste is a good idea, but it's not a way to dispose of waste that is already made. Disposal means getting rid of it, like by diluting or storing it until it becomes harmless.

🎯 Exam Tip: Understand the difference between preventing waste (like limiting generation) and methods for its disposal or treatment.

 

Question 13. E – Wastes are basically..............
(a) Poly iodinated biphenyl based compounds
(b) Polychlorinated biphenyl based compounds
(c) Polyhydroxy biphenyl based compounds
(d) Poly acetyl biphenyl based compounds
Answer: (c) Polyhydroxy biphenyl based compounds
In simple words: E-wastes mainly contain special chemicals called polyhydroxy biphenyl compounds.

🎯 Exam Tip: Knowing the hazardous components of e-waste, like specific chemical compounds, is important for understanding their environmental impact.

 

Question 14. Identify the correct statement indicating 4Rs of treating water.
(a) Regenerate, Reduce, Reuse and Recycle
(b) Refuse, Reduce, Rejenuvate, and Reuse
(c) Redeem, Refuse, Rejenuvate and Reduce
(d) Refuse, Reduce, Rescue and Recycle.
Answer: (d) Refuse, Reduce, Rescue and Recycle.
In simple words: To treat water with the 4Rs, we should say 'no' to waste, use less, clean and save water, and then recycle it.

🎯 Exam Tip: Familiarize yourself with different 'R' principles (3Rs, 4Rs, 5Rs) in environmental management, noting any variations for specific contexts like water treatment.

 

Question 15. UN conference on Sustainable development in 2012 was held at..............
(a) Ruanda
(b) Rio de Janeiro
(c) Geneva
Answer: (b) Rio de Janeiro
In simple words: The big UN meeting about sustainable development in 2012 happened in Rio de Janeiro.

🎯 Exam Tip: Key international conferences and their locations/dates are often asked in environmental studies, so note them carefully.

 

Question 16. The molecular formula for ozone is...
(a) O2
(b) O4
(c) O3
(d) O7
Answer: (c) O3
In simple words: Ozone is a type of oxygen with three atoms, written as \( O_3 \).

🎯 Exam Tip: Always ensure you know the chemical formulas of key environmental gases like ozone, carbon dioxide, and methane.

 

Question 17. World Ozone Day was observed on........
(a) September 16th
(b) October 12th
(e) December 1st
(d) August 18th
Answer: (a) September 16th
In simple words: We celebrate World Ozone Day on September 16th each year to remember the ozone layer and how to protect it.

🎯 Exam Tip: Remember important environmental dates as they often relate to significant agreements or events.

 

Question 18. Who is the leader of Chipko Movement?
Answer: The Chipko Movement, a grassroots effort to protect trees, was led by Sunderlal Bahuguna. He was a prominent environmentalist known for his non-violent activism, advocating for forest conservation through community participation.
In simple words: Sunderlal Bahuguna was the main leader of the Chipko Movement, which worked to save trees.

🎯 Exam Tip: When asked about movements, always identify the key figures and their contributions.

 

Question 19. I am called the 'Forest Man of India? Who am I?
Answer: Jadav Payeng is widely known as the 'Forest Man of India' because he single-handedly planted and nurtured a large forest on a barren land in Assam, India. His dedication transformed an eroded sandbar into a thriving ecosystem, showing the power of individual action.
In simple words: Jadav Payeng is known as the 'Forest Man of India' because he planted a whole forest by himself.

🎯 Exam Tip: Be ready for questions that test your knowledge of famous environmentalists and their specific achievements.

 

Question 20. Identify the incorrect statement.
(i) EcoSan toilets is a sustainable way of handling human excreta by using dry composting toilets
(ii) It reduces wastewater generation
(iii) It is based on the recovery and recycling of nutrients from excreta
(iv) EcoSan toilets are used in several parts of India and Srilanka.
(a) i and ii only
(b) iii and iv only
(c) all the above
(d) none of the above
Answer: (d) none of the above
In simple words: EcoSan toilets are a good way to manage human waste. They use dry composting, save water, turn waste into useful nutrients, and are used in places like India and Sri Lanka. All these points are true.

🎯 Exam Tip: For 'incorrect statement' questions, evaluate each option carefully. If all statements are true, then 'none of the options' is the correct answer.

 

Question 21. What is the name of the action plan for sustainable development framed at the Rio conference in 1992?
(a) Action 21
(b) Declaration 21
(c) Protocol 21
(d) Agenda 21
Answer: (d) Agenda 21
In simple words: The plan made at the Rio conference in 1992 to help the world develop in a sustainable way is called Agenda 21.

🎯 Exam Tip: Recall major international environmental agreements and their specific names, like Agenda 21 for the Rio Summit.

 

Question 22. Eutrophication is a result of................
(a) Deforestation
(b) Vehicle emission
(c) Pesticides
(d) Industrial effluent
Answer: (c) Pesticides
In simple words: Eutrophication happens because of too many nutrients in water. These nutrients can come from things like pesticides used in farming, making algae grow too much.

🎯 Exam Tip: Understand that eutrophication is primarily caused by nutrient enrichment, often from agricultural runoff containing fertilizers and some pesticides.

 

Question 23. BOD stands for.
(a) Biological Oxidation Demand
(b) Biotic Oxygen Deficient
(c) Biological Oxygen Deficit
(d) Biochemical Oxidation Deficit
Answer: (a) Biological Oxidation Demand
In simple words: BOD means Biological Oxidation Demand. It tells us how much oxygen tiny living things need to break down dirt in water.

🎯 Exam Tip: Knowing the full forms of common environmental acronyms like BOD, COD, AQI, and PAN is essential.

 

Question 24. The stratosphere is mainly depleted by..............
(a) Excess CO
(b) CFC's
(c) Ozone
(cl) Excess CO2
Answer: (b) CFC's
In simple words: The ozone layer in the sky is mostly thinned by chemicals called CFCs.

🎯 Exam Tip: Recognize CFCs as the main culprits behind ozone layer depletion and understand their chemical action.

 

Question 25. Treatment of sewage involves
(a) Floatation, Filtration and Sedimentation of suspended particles
(b) Aerating it for bacterial action
(c) Disinfection for pathogens to make it harmless
(d) All of the options
Answer: (d) All of the options
In simple words: Treating sewage means many steps. It includes floating and settling particles, filtering, adding air for good bacteria, and killing germs. All these are part of the process.

🎯 Exam Tip: Understand the different stages of sewage treatment (primary, secondary, tertiary) and the purpose of each step.

 

Question 26. Assertion (A): The ozone layer protects the UV rays entering the Earth. Reason (R): UV rays may cause melanoma
(a) A is right R is wrong
(b) A is the wrong R is right
(c) Both A and R are correct
(d) R explains A
Answer: (d) R explains A
In simple words: The ozone layer stops harmful UV rays from reaching Earth. UV rays can cause skin cancer like melanoma. The fact that UV rays cause melanoma shows why the ozone layer's protection is so important.

🎯 Exam Tip: For Assertion-Reason questions, first check if both A and R are true. Then, test if R provides a direct explanation or cause for A, or if it's merely a related true statement.

 

Question 27. Assertion (A): Evolution of Greenhouse gases leads to Global warming Reason (R): The energy released by the greenhouse gases move away from the atmospheric surface
(a) A is right R is wrong
(b) A is wrong R is right
(c) Both A and R are correct
(d) R explains A
Answer: (a) A is right R is wrong
In simple words: More greenhouse gases cause global warming, which is true. But the idea that these gases move energy away from Earth is wrong; they actually trap heat.

🎯 Exam Tip: Ensure a clear understanding of the greenhouse effect mechanism: greenhouse gases absorb and re-emit infrared radiation, trapping heat, rather than allowing it to escape.

 

Question 28. Statement (1): Incomplete combination of fossil fuels releases CO Statement (2): CO is a GHG
(a) Statement 1 is true, statement 2 is false
(b) Statement 1 is false, statement 2 is true
(c) Both Statements 1 and 2 are true
(d) Both statements 1 and 2 are false
Answer: (a) Statement 1 is true, statement 2 is false
In simple words: When fuels don't burn completely, they make carbon monoxide (CO), which is true. But CO is not a greenhouse gas; that is false. Carbon dioxide (\( CO_2 \)) is the greenhouse gas.

🎯 Exam Tip: Differentiate between carbon monoxide (CO) as a toxic air pollutant and carbon dioxide (\( CO_2 \)) as the primary carbon-based greenhouse gas.

 

Question 29. Statement (1): The intensity of noise is measured in the dobson (dB) unit. Statement (2): Noise provides immense bliss.
(a) Statement 1 is true, statement 2 is false
(b) Statement 1 is false, statement 2 is true
(c) Both Statements 1 and 2 are true
(d) Both statements 1 and 2 are false
Answer: (d) Both statements 1 and 2 are false.
In simple words: Statement 1 is wrong because noise is measured in decibels, not Dobson units. Statement 2 is also wrong because loud noise usually makes people annoyed, not happy.

🎯 Exam Tip: Be precise with units of measurement (decibel vs. Dobson) and understand the general impacts of pollutants like noise.

 

Question 30. The threshold of noise level is.............. 120db
Answer: The threshold of noise level, meaning the point where noise becomes extremely loud and potentially damaging, is often considered to be around 120 decibels (dB). Exposure to such high levels can cause immediate hearing damage or even pain.
In simple words: A noise level of 120 decibels (dB) is often seen as the point where it becomes dangerously loud, almost like a warning limit.

🎯 Exam Tip: Recall specific threshold values for environmental parameters, like the danger level for noise, as these indicate critical points.

 

Question 31. Chemicals used in agriculture as fertilizer and pesticides are generally called as
Answer: Chemicals used in farming to help crops grow (fertilizers) or to kill pests (pesticides) are collectively known as agrochemicals. These substances play a significant role in modern agriculture but also pose environmental challenges.
In simple words: Chemicals like fertilizers and pesticides used in farming are called agrochemicals.

🎯 Exam Tip: Use precise terminology for substances used in agriculture and understand their dual role in farming and the environment.

12th Bio Zoology Guide Environmental Issues Two Marks Questions and Answers

 

Question 1.
Answer: Pollution refers to any unwanted change in the environment's natural state, affecting its physical, chemical, or biological makeup. These changes can be caused by either natural events or human activities, impacting ecosystems and health.
In simple words: Pollution means any bad change to nature – its look, its chemicals, or its living things. This can happen because of nature or because of people.

🎯 Exam Tip: A clear definition of pollution, highlighting its multi-faceted impact (physical, chemical, biological) and sources (natural, human), is key.

 

Question 2. What is air pollution?
Answer: Air pollution occurs when the natural makeup of Earth's atmosphere changes in unwanted ways. This can be due to natural events or, more commonly, human activities which introduce harmful substances, leading to various environmental and health issues.
In simple words: Air pollution is when bad things change the air we breathe, either from nature or from human actions.

🎯 Exam Tip: Define air pollution by focusing on changes to atmospheric composition and identifying both natural and anthropogenic sources.

 

Question 3. Classify air pollutants.
Answer: Air pollutants can be classified mainly into two types. First, there are particulate matters, which are tiny solid particles like dust (for example, PM 2.5 and PM 10). Second, there are various harmful gases, such as sulfur oxides (SOx), nitrogen oxides (NOx), carbon monoxide (CO), and carbon dioxide (\( CO_2 \)), released into the atmosphere.
In simple words: Air pollutants are grouped into two types: tiny solid bits like dust (particulate matter) and harmful gases such as SOx, NOx, CO, and \( CO_2 \).

🎯 Exam Tip: When classifying pollutants, remember the two broad categories (particulate matter and gases) and provide specific examples for each to score well.

 

Question 4. What are particulate matters? Give examples.
Answer: Particulate matters are extremely small solid or liquid particles that float in gases, like air. They originate from sources such as burning fossil fuels, fly ash from power plants, wildfires, asbestos mines, and cement factories, contributing significantly to air pollution and health problems.
In simple words: Particulate matters are tiny solid pieces floating in the air. They come from burning fuels, power plants, forest fires, and factories, causing air pollution.

🎯 Exam Tip: When defining particulate matter, emphasize its small size and airborne nature, and list diverse sources from industry to natural events.

 

Question 5. Name the secondary pollutant in photochemical smog. Mention its adverse effect.
Answer: Peroxyacetyl nitrate (PAN) is a key secondary pollutant found in photochemical smog. This compound is not stable and breaks down to release other chemicals, including nitrogen dioxide, which can cause significant irritation to the eyes, leading to discomfort and vision problems.
In simple words: Peroxyacetyl nitrate (PAN) is a harmful pollutant in smog that makes eyes itchy. It is made when sunlight reacts with other gases in the air.

🎯 Exam Tip: For photochemical smog, identify PAN as the secondary pollutant and its most common adverse effect (eye irritation).

 

Question 6. How ozone hole is developed?
Answer: The 'ozone hole' develops due to ozone depletion, which is the thinning of the ozone layer in the stratosphere. This thinning primarily occurs when chemicals like chlorofluorocarbons (CFCs) reach the stratosphere and break down ozone molecules. When this protective layer becomes thinner, more harmful UV rays from the sun reach Earth, increasing risks like skin cancer.
In simple words: The ozone hole forms when the ozone layer in the sky gets thinner. This happens mostly because of chemicals like CFCs that break down the ozone. When the layer is thin, more bad UV rays from the sun can come to Earth.

🎯 Exam Tip: Explain ozone hole formation by connecting ozone depletion, the role of CFCs, and the consequent increase in harmful UV radiation reaching Earth.

 

Question 7. List out the greenhouse gases. (Any four)
Answer: The main greenhouse gases that trap heat in Earth's atmosphere include carbon dioxide (\( CO_2 \)), chlorofluorocarbons (CFCs), methane (\( CH_4 \)), and nitrous oxide (\( N_2O \)). These gases contribute to the greenhouse effect and global warming by absorbing and re-emitting infrared radiation.
In simple words: Four important greenhouse gases are carbon dioxide, CFCs, methane, and nitrous oxide. These gases help keep the Earth warm.

🎯 Exam Tip: Know at least four major greenhouse gases by name and their chemical formulas where applicable, as they are fundamental to understanding climate change.

 

Question 8. What is Acid rain?
Answer: Acid rain is rain, snow, or fog that is much more acidic than normal because it contains harmful acidic chemicals. These chemicals, mainly sulfuric acid and nitric acid, come from air pollution. Acid rain damages trees, harms farm crops, hurts sea creatures like coral, and can cause buildings and metals to rust or break down.
In simple words: Acid rain is rain with harmful acids like sulfuric acid and nitric acid, caused by air pollution. It damages plants, animals in the water, and buildings.

🎯 Exam Tip: When defining acid rain, specify the key acidic components (sulfuric, nitric acid) and list its varied negative impacts on the environment.

 

Question 9. Point out any two non-point sources of water pollution.
Answer: Non-point sources of water pollution are those that are spread out and cannot be traced to a single specific location. Two common examples are:
• Agricultural chemical runoff, where fertilizers and pesticides wash off fields into rivers.
• The widespread dumping of plastics into various water bodies, which is difficult to pinpoint to one exact origin. These diffuse sources make pollution control more challenging.
In simple words: Non-point sources of water pollution are like diffused sources. Two examples are chemicals washing off farms into water, and plastics being thrown into rivers and oceans.

🎯 Exam Tip: Distinguish between point sources (e.g., factory pipe) and non-point sources (e.g., agricultural runoff) of pollution, providing clear examples for each.

 

Question 10. How will you define noise pollution?
Answer: Noise pollution is defined as any loud or unwanted sound that is unpleasant or harmful, disturbing the quality of life for humans and animals. When excessive noise levels are present in an environment, it leads to various negative impacts such as stress, hearing loss, and disrupted ecosystems.
In simple words: Noise pollution is too much loud or unwanted sound that harms living things and makes life difficult.

🎯 Exam Tip: Define noise pollution by emphasizing its unwanted nature and its potential to disrupt well-being, not just its loudness.

 

Question 11. 'Expand USEPA and MOEFCC.
Answer:
USEPA: The United States Environmental Protection Agency.
MOEFCC: Ministry of Environment, Forest, and Climate Change. These organizations play crucial roles in setting and enforcing environmental policies in their respective countries.
In simple words: USEPA is the United States Environmental Protection Agency. MOEFCC means the Ministry of Environment, Forest, and Climate Change.

🎯 Exam Tip: Memorize the full forms of important environmental organizations and ministries, especially those relevant to your curriculum.

 

Question 12. What are agrochemicals?
Answer: Agrochemicals, also known as agrichemicals, are special chemical products used in farming. They include fertilizers, which help plants grow better, and pesticides, which control pests that can harm crops. These chemicals help increase food production but must be used carefully to avoid environmental harm.
In simple words: Agrochemicals are chemicals like fertilizers and pesticides used in farming to help plants grow and kill pests.

🎯 Exam Tip: Provide a concise definition of agrochemicals, listing both their purpose (plant growth, pest control) and key examples.

 

Question 13. Which organism is affected by colony collapse syndrome? What will be the impact.
Answer: Colony Collapse Syndrome (CCS) primarily affects honey bees. This serious problem, often linked to pesticides and herbicides, causes adult worker bees to disappear, leading to the collapse of entire beehives. The impact is significant, as it not only destroys bee colonies but also reduces agricultural productivity, as bees are crucial for pollinating many crops.
In simple words: Colony Collapse Syndrome affects honey bees, often because of chemicals like pesticides. It kills bee colonies and also reduces how much food farms can grow because bees help plants make fruits and seeds.

🎯 Exam Tip: Focus on honey bees as the organism affected by CCS and highlight the dual impact: hive destruction and reduced agricultural output.

 

Question 14. Define the term eutrophication.
Answer: Eutrophication is a process where water bodies, such as lakes and rivers, become overly enriched with nutrients, typically from land runoff. This excess of nutrients causes a dense growth of aquatic plant life, particularly algae, which can then deplete oxygen in the water, harming other aquatic organisms.
In simple words: Eutrophication is when too many nutrients from land wash into water, making too many plants grow. This uses up the oxygen in the water and can kill fish.

🎯 Exam Tip: Define eutrophication by linking nutrient runoff, excessive plant growth (algal blooms), and subsequent oxygen depletion in water bodies.

 

Question 15. What is meant by accelerated eutrophication?
Answer: Accelerated eutrophication, also known as cultural eutrophication, refers to the rapid increase in nutrient enrichment in water bodies caused by human activities. Pollutants from sources such as industrial waste and domestic sewage significantly speed up the natural aging process of lakes, leading to quick overgrowth of plants and depletion of oxygen.
In simple words: Accelerated eutrophication is when human activities, like releasing wastewater from homes and factories, quickly add many nutrients to water. This makes the water bodies age faster and causes more plant growth than usual.

🎯 Exam Tip: Distinguish accelerated (cultural) eutrophication from natural eutrophication by emphasizing human-caused nutrient input and the rapid acceleration of the process.

 

Question 16. List out the chemical methods of wastewater treatment.
Answer: Chemical methods for treating wastewater often involve reactions that change harmful substances into less harmful forms. This can include processes that lead to:
• The formation of insoluble solids that can be easily removed.
• The production of an insoluble gas, which can then be safely vented.
• Changing non-biodegradable substances into ones that can be broken down by living organisms.
• Using oxidation or reduction reactions to transform pollutants into non-objectionable substances. These methods are crucial for purifying water for reuse or safe discharge.
In simple words: Chemical ways to clean wastewater include making solid bits that can be removed, creating gases that float away, changing hard-to-break-down stuff into easier ones, and using special reactions to make bad things harmless.

🎯 Exam Tip: When listing chemical methods, focus on the transformations involved (e.g., precipitation, gas formation, degradation, redox reactions) rather than specific chemicals, to show a broad understanding.

 

Question 17. Expand RZWT and DEWATS.
Answer:
RZWT: Root Zone Wastewater Treatment
DEWATS: Decentralized Wastewater Treatment System These are eco-friendly and localized approaches to managing wastewater, often involving natural processes or smaller, distributed treatment units.
In simple words: RZWT is Root Zone Wastewater Treatment. DEWATS means Decentralized Wastewater Treatment System.

🎯 Exam Tip: Be ready to expand acronyms related to wastewater treatment technologies, understanding what each system broadly represents.

 

Question 18. What are the medical wastes?
Answer: Medical wastes are any types of waste materials that contain infectious substances. These are typically generated from healthcare facilities such as hospitals, medical laboratories, research centers, pharmaceutical companies, and veterinary clinics. Proper disposal of medical waste is critical to prevent the spread of diseases.
In simple words: Medical waste is any trash from places like hospitals, labs, and vet clinics that has infectious material. It must be handled carefully.

🎯 Exam Tip: Define medical waste by focusing on its infectious nature and the types of healthcare facilities that produce it.

 

Question 19. What does 4R stand for?
Answer: The '4R' principle in waste management is a set of strategies to minimize environmental impact. It stands for Refuse (saying no to unnecessary items), Reduce (using less), Reuse (finding new uses for items), and Recycle (processing materials to make new products). This framework is especially useful for managing plastic waste sustainably.
In simple words: The 4R stands for Refuse, Reduce, Reuse, and Recycle. These are ways to manage plastic waste better.

🎯 Exam Tip: Remember the 4Rs in the correct order and understand the meaning of each 'R' in the context of waste management.

 

Question 20. Define deforestation.
Answer: Deforestation is the permanent removal of forest areas to convert the land for other uses, such as agriculture, cattle ranching, or urban development. This process involves cutting down and burning trees, leading to significant environmental impacts like soil erosion and climate change.
In simple words: Deforestation means cutting down and clearing forests permanently, often to use the land for farms or buildings.

🎯 Exam Tip: Provide a clear definition of deforestation, emphasizing the permanent removal of forests and the conversion of land for other purposes.

12th Bio Zoology Guide Environmental Issues Three Marks Questions and Answers

 

Question 21.
Answer: Pollutants are classified based on how quickly they break down into simpler components.
a) Rapidly degradable or non-persistent pollutants: These break down quickly through natural processes. Common examples include household sewage and vegetable waste, which decompose relatively fast.
b) Slowly degradable or persistent pollutants: These remain in the environment for extended periods, sometimes for decades, because they degrade very slowly. DDT is a well-known example of a persistent pollutant due to its long-lasting nature.
In simple words: Pollutants are grouped by how fast they break down. Some are 'rapidly degradable' like food waste, which break down fast. Others are 'slowly degradable' like DDT, which stay in nature for many years.

🎯 Exam Tip: When classifying pollutants based on degradability, clearly define both rapidly and slowly degradable types, providing specific examples for each.

 

Question 22. What are the main sources of air pollution?
Answer: Air pollution comes from several major sources:
• Transport sources: These are mobile sources like cars, buses, airplanes, trucks, and trains, which release exhaust emissions.
• Stationary sources: These are fixed locations such as power plants, incinerators, oil refineries, and factories, emitting pollutants from their operations.
• Area sources: These include broad, diffused sources like agricultural activities (e.g., wood/stubble burning) and residential fireplaces.
• Natural sources: These are naturally occurring phenomena such as wind-blown dust, wildfires, and volcanic eruptions, which release particulate matter and gases into the atmosphere.
In simple words: Air pollution comes from many places: vehicles like cars, big fixed places like power plants and factories, large areas like farms burning stubble, and natural events like dust storms and volcanoes.

🎯 Exam Tip: Categorize air pollution sources into broad types (transport, stationary, area, natural) and give specific examples for each to show comprehensive understanding.

 

Question 23. Define AQI. What will be the air quality if AQI is between 0-50?
Answer: The Air Quality Index (AQI) is a standard numerical scale that government agencies use to inform the public about current air pollution levels and associated health risks. An AQI value between 0 and 50 indicates that the air quality is considered good, meaning air pollution poses little or no risk and is generally satisfactory.
In simple words: AQI, or Air Quality Index, is a number that tells people how clean or dirty the air is right now. If the AQI is between 0 and 50, it means the air quality is good and safe.

🎯 Exam Tip: When defining AQI, state its purpose (communicating air quality) and remember the specific range (0-50) for 'good' air quality.

 

Question 24. Explain the three main sources of water pollution.
Answer: Water pollution comes from three main sources: point sources, non-point sources, and leaks or spills. Point sources are when pollutants enter water from a clear, single spot, like pipes from factories or sewage systems. Non-point sources are harder to trace back to one place, such as chemical runoff from farms or plastics dumped widely in water. Leaks and spills happen from things like shipping accidents, offshore oil rigs, or oil leaks into the sea. These different sources make water unhealthy for plants, animals, and humans.
In simple words: Water gets polluted from specific pipes (point sources), wide areas like farms (non-point sources), or accidents like oil spills.

🎯 Exam Tip: When explaining sources of pollution, always give clear examples for each type to show understanding.

 

Question 25. What will be the impact of water pollution on the ecosystem?
Answer: Water pollution greatly harms ecosystems, especially those in water. It can damage or destroy natural habitats and living spaces for different animals and plants. Pollutants affect the survival of many organisms and make the soil less fertile. When soil becomes unhealthy, the whole system can become unfit for living creatures. Protecting water quality is essential for all life on Earth.
In simple words: Water pollution hurts nature, especially water-living plants and animals, by damaging their homes and making the environment toxic.

🎯 Exam Tip: Focus on explaining the effects on both living organisms (survival) and the physical environment (habitats, soil fertility).

 

Question 26. Suggest a few ways to control water pollution.
Answer: Some ways to control water pollution include:
• Regulating or controlling pollutant discharge where it is created.
• Pre-treating wastewater using scientific methods before releasing it to municipal treatment plants.
• Setting up Sewage Treatment Plants (STP) and Effluent Treatment Plants (ETP) to clean water.
• Regulating or limiting the use of man-made fertilizers and pesticides.
• Raising public awareness and getting people involved is very important. These actions help keep our water clean and safe for everyone.
In simple words: We can control water pollution by cleaning dirty water before it goes out, using fewer chemicals on farms, and teaching everyone to help keep water clean.

🎯 Exam Tip: When suggesting solutions, try to cover different aspects like industrial control, agricultural practices, and public involvement.

 

Question 27. Write a note on the 'Namami Ganga' programme.
Answer: The 'Namami Ganga' Programme is a big plan started by the Indian government in June 2014. It is also known as the National Mission for Clean Ganga. The main goals of this program are to stop pollution in the River Ganga, protect it, and bring it back to life. The government set aside 20,000 crores of rupees for this project. This initiative aims to ensure the Ganges remains a vital resource for both people and nature.
In simple words: The Namami Ganga program is a large government plan started in 2014 to clean up, protect, and make the River Ganga healthy again.

🎯 Exam Tip: Remember to mention the year of launch, the main objective, and the program's official name (National Mission for Clean Ganga).

 

Question 28. List out the sources of noise pollution.
Answer: Many things around us create noise pollution. These include vehicle engines, loud horns, music systems, trains, and low-flying aircraft. Factories, sirens, motors, drills, crushers, and compressor machines also make a lot of noise. Additionally, firecrackers, explosives, and very fast supersonic transports are common sources. All these sounds together can harm our environment and health.
In simple words: Noise pollution comes from cars, trains, airplanes, machines, firecrackers, and loud music.

🎯 Exam Tip: Provide a variety of examples from different categories (transportation, industrial, recreational) to show a comprehensive understanding.

 

Question 29. State the role of Government in controlled Noise pollution.
Answer: Governments play a key role in controlling noise pollution through laws and rules. For example, the Noise Pollution (Regulation and Control) Rules 2000, and the Tamil Nadu State Environment Policy 2017, provide legal steps to manage noise. These rules set limits on how loud noise can be in different areas. For instance, in commercial areas, the daytime noise limit is 65 decibels (dB), and at night, it's 55 dB. By setting and enforcing these limits, governments help create quieter, healthier environments for everyone.
In simple words: The government makes rules and laws, like the Noise Pollution Rules 2000, to set limits on how loud noise can be in different places to control pollution.

🎯 Exam Tip: It is good to mention specific regulations or policies (like the 2000 rules) and give an example of a permissible noise limit.

 

Question 30. Comment on Bio-magnification of DDT.
Answer: Biomagnification happens when substances that cannot be broken down, like DDT, enter the food chain. These substances do not get metabolized, broken down, or removed from the body. Instead, they build up in living organisms. As smaller animals are eaten by larger ones, the concentration of these substances increases at each higher level of the food chain. This buildup can become toxic and even deadly. Biomagnification is a serious problem for chemicals like DDT and mercury. This process shows how harmful pollutants can become more dangerous as they move through an ecosystem.
In simple words: Biomagnification is when harmful chemicals like DDT build up in living things and become more concentrated as they move up the food chain, making them dangerous.

🎯 Exam Tip: Clearly define biomagnification and explain why non-degradable substances are particularly problematic. Mention DDT as a key example.

 

Question 31. Explain the biological methods of wastewater treatment.
Answer: Biological methods use living organisms to clean wastewater. These methods include:
• Bioremediation: This uses aerobic treatments, like oxidation ponds and aeration lagoons, and anaerobic treatments, like anaerobic bioreactors and lagoons.
• Phytoremediation: This uses plants in constructed wetlands and Root Zone Wastewater Treatment (RZWT) systems. These methods also include Decentralized Waste Water Treatment Systems (DEWATS). These natural processes help break down harmful substances in the water, making it safer.
In simple words: Biological wastewater treatment uses living things like bacteria and plants to clean dirty water.

🎯 Exam Tip: When discussing biological methods, distinguish between bioremediation (microorganisms) and phytoremediation (plants) and give examples for each.

 

Question 32. Write a note on organic farming.
Answer: Organic farming is a way of farming that focuses on keeping the soil healthy and alive. It uses natural methods instead of chemical fertilizers and pesticides. Farmers use organic wastes like crop remains, animal waste, and other natural materials, along with helpful microbes (biofertilizers). This helps release nutrients to crops, leading to sustainable production. Organic farming aims to grow food in an eco-friendly way, without causing pollution. This approach supports biodiversity and ecosystem health.
In simple words: Organic farming is a natural way to grow crops using organic waste and good microbes to keep the soil healthy, without using harmful chemicals.

🎯 Exam Tip: Key terms to include are "soil health," "organic wastes," "biofertilizers," and "eco-friendly" when describing organic farming.

 

Question 33. How radioactive wastes are generated?
Answer: Radioactive wastes are created during different processes in nuclear power plants. This waste can be in gas, liquid, or solid forms. Its level of radioactivity can vary, meaning some waste stays radioactive for only a few hours, while others can remain so for hundreds of thousands of years. The level of radioactivity also helps classify it into different types, like Exempt Waste, Low and Intermediate Level Waste, and High-Level Waste. Safe handling and disposal of radioactive waste are crucial due to its long-term hazards.
In simple words: Radioactive wastes come from nuclear power plants and can be solid, liquid, or gas. They stay dangerous for different lengths of time, some for many years.

🎯 Exam Tip: Mention the primary source (nuclear power plants) and the variability in radioactivity duration and physical forms (gas, liquid, solid).

 

Question 34. What are geological repositories?
Answer: Geological repositories are special places dug deep within stable rock formations. They are designed to safely store nuclear waste for a very long time. The main goal is to keep the waste isolated and contained, preventing it from harming people or the environment in the future. These repositories do not need constant human maintenance once sealed. In India, places like Tarapur and Kalpakkam have facilities for storing spent nuclear fuel. This long-term storage solution is essential for managing dangerous radioactive materials.
In simple words: Geological repositories are deep underground storage sites in stable rock, built to safely hold nuclear waste for a very long time without needing much care.

🎯 Exam Tip: Highlight "deep geological environment," "long-term isolation," and "no future maintenance" as key characteristics of these repositories.

 

Question 35. Give an account of E-waste.
Answer: E-waste, or electronic waste, includes discarded electrical and electronic devices. This also covers any refuse created during the making or use of these devices and their parts. E-waste is a growing problem because electronic equipment often contains dangerous substances. For example, personal computers can have lead in their screens and solder, mercury in switches, and cobalt in steel parts. Most e-waste is based on PCBs (Polychlorinated biphenyl), which do not break down easily. Proper disposal is essential to prevent harm to the environment and human health.
In simple words: E-waste is old electronic stuff like computers and phones that we throw away. It is a problem because it has harmful chemicals that don't break down easily.

🎯 Exam Tip: Explain what e-waste is, why it's a problem (hazardous substances), and give examples of these substances and devices.

 

Question 36. What will be the impact of global warming?
Answer: Global warming will have a big impact on people and nature. As the Earth's average temperature rises, rainfall patterns will change. This means we can expect more extreme wet and dry weather, leading to floods and desertification. Coastal areas will face more dangers from storm surges as sea levels go up. Animals and plants will have to move to new places or might disappear if they cannot adapt to the changing climate. This can also cause food shortages and affect the health of both people and other living things. Global warming affects many aspects of life on Earth.
In simple words: Global warming will cause changing weather, more floods and dry spells, rising sea levels, and harm plants, animals, and even our food supply.

🎯 Exam Tip: When describing impacts, categorize them into environmental (temperature, precipitation, sea level) and biological (species migration, food shortage, health) effects.

 

Question 38. How Ozone depletion can be controlled?
Answer: Ozone layer depletion can be controlled in several ways:
• We need to reduce or stop using CFCs (chlorofluorocarbons), which are refrigerants harmful to the ozone layer.
• Minimizing the use of other chemicals like halons and halocarbons also helps.
• It is important to create awareness about chemicals that damage the ozone layer. These steps help protect the fragile ozone layer that shields Earth from harmful UV rays.
In simple words: We can control ozone depletion by using fewer harmful chemicals like CFCs and teaching people about ozone-destroying agents.

🎯 Exam Tip: The Montreal Protocol is a key international agreement related to ozone depletion; mentioning it can strengthen your answer.

 

Question 39. What will be the effect of Ozone depletion on Earth?
Answer: Ozone depletion allows more harmful UV rays to reach Earth. These rays can penetrate deep into the skin, leading to early skin aging and wrinkles. They can also weaken the immune system and cause skin cancer (like melanoma). Long-term exposure to UV rays can damage the eyes. Furthermore, UV radiation can damage DNA itself by creating free radicals and reactive oxygen. Protecting the ozone layer is crucial for human health and overall environmental well-being.
In simple words: Less ozone means more harmful UV rays reach us, causing skin aging, skin cancer, eye damage, and weakening our body's defense system.

🎯 Exam Tip: Focus on specific health effects like skin aging, cancer, immune suppression, and eye damage caused by increased UV radiation.

 

Question 40. Write a brief note on the Chipko movement.
Answer: The Chipko movement was a significant environmental protection movement in India during the 1970s. It was inspired by the Bishnois, who are known for protecting forests. The movement's leader was Sunderlal Bahuguna. In this movement, villagers, especially women, would hug trees to prevent contractors from cutting them down. This act of peaceful resistance saved many forests and highlighted the importance of community involvement in conservation. The movement showed how people could stand up for nature.
In simple words: The Chipko movement was a famous Indian protest in the 1970s where villagers, led by Sunderlal Bahuguna, hugged trees to stop them from being cut down.

🎯 Exam Tip: Remember to include the key details: location (India), time (1970s), leader (Sunderlal Bahuguna), and the main action (hugging trees).

 

Question 41. What do you mean by Ecosan Toilets?
Answer: EcoSan toilets are a sustainable way to handle human waste. They are dry composting toilets, meaning they don't use water to flush. These toilets help reduce wastewater generation. They also create natural fertilizer from recycled human waste, which is a great substitute for chemical fertilizers. EcoSan toilets are based on the idea of recovering and reusing nutrients from human waste, providing a valuable resource for agriculture. These toilets are used in different parts of India and Sri Lanka. This system helps save water and turns waste into something useful.
In simple words: EcoSan toilets are dry toilets that save water and turn human waste into natural fertilizer, which is good for farming.

🎯 Exam Tip: Emphasize the "dry composting" aspect, the reduction of wastewater, and the creation of natural fertilizer as key benefits of EcoSan toilets.

 

Question 42. List out the effects of air pollution.
Answer: Air pollution has many harmful effects:
• It affects all living organisms because they need the atmosphere to breathe.
• It causes irritation in the throat, nose, lungs, and eyes.
• It leads to breathing problems and makes existing conditions like emphysema and asthma worse.
• Contaminated air weakens the body's defense system, making it harder to fight infections in the respiratory system.
• Breathing polluted air frequently increases the risk of heart diseases, hardening arteries, and triggering heart attacks.
• People who exercise outdoors might be more affected because they breathe deeper and faster, so it's better to do so in places with many trees.
• Gas leaks can be deadly or reduce air quality.
• Carbon monoxide (CO) in the air interferes with oxygen transport in the blood, causing headaches and blurred vision at low levels, and coma or death at high levels. Air pollution is a serious threat to public health.
In simple words: Air pollution makes it hard to breathe, causes eye and throat irritation, harms our lungs and heart, and makes our body weaker against diseases.

🎯 Exam Tip: For comprehensive answers, list effects on different body systems (respiratory, cardiovascular, immune) and general well-being.

 

Question 43. How air pollution can be controlled?
Answer: Air pollution can be controlled by taking various measures to remove pollutants, reduce their presence, or prevent them from entering the atmosphere:
• Planting trees is a great way to reduce urban particulate and gaseous pollution.
• Forests act as "carbon sinks," meaning they absorb carbon and act as the "lungs" of our planet.
• Catalytic converters in vehicles help reduce harmful gases significantly.
• Diesel exhaust filters in cars reduce tiny particles.
• Electrostatic precipitators are used to reduce industrial pollutants released from factories.
• Using affordable air pollution treatment systems like indoor plants and advanced biofilters can improve air quality inside buildings. These combined efforts are essential for cleaner air.
In simple words: We can control air pollution by planting trees, using special filters in vehicles and factories, and by cleaning indoor air.

🎯 Exam Tip: When listing control methods, provide a mix of natural solutions (trees/forests) and technological solutions (converters, filters) for a complete answer.

 

Question 44. Point out the effects of Noise pollution.
Answer: Noise pollution has several harmful effects on health and well-being:
• According to the USEPA (United States Environmental Protection Agency), noise can lead to heart disease, high blood pressure, stress-related illnesses, sleep problems, hearing loss, and reduced productivity.
• It increases stress and tension, causing nervousness, irritability, anxiety, depression, and panic attacks.
• People can suffer from peptic ulcers, severe headaches, and memory loss.
• Marine animals are negatively affected by noise from offshore activities and port operations, disrupting their communication and navigation.
• Loud noises from firecrackers and increased air traffic often frighten animals. Reducing noise is crucial for a healthier environment.
In simple words: Noise pollution can cause heart disease, stress, sleep problems, hearing loss, headaches, and harm both humans and animals.

🎯 Exam Tip: Categorize effects into physical health, mental health, and impact on wildlife to provide a structured answer.

 

Question 45. How agrochemicals affect the ecosystem?
Answer: Agrochemicals, like pesticides and fertilizers, can harm the ecosystem in many ways:
• They can kill helpful bacteria and other tiny organisms in the soil.
• These chemicals can cause eutrophication in water bodies, leading to excessive algae growth.
• They can harm aquatic animals and reduce their numbers.
• Water containing even tiny amounts of pesticides becomes unsafe for human consumption.
• Small particles (aerosols) and residues of these chemicals cause air pollution.
• Breathing contaminated air can lead to breathing problems.
• Consuming contaminated food or water can cause poisoning, side effects, and long-term health issues.
• These chemicals can cause skin rashes and eye irritation.
• Many agrochemicals are known to cause cancer.
• Beneficial insects and animals, like pollinators, can also be affected. The use of agrochemicals requires careful management to minimize these environmental and health risks.
In simple words: Agrochemicals harm soil organisms, pollute water, kill water animals, make water unsafe to drink, pollute air, and can cause many health problems like cancer.

🎯 Exam Tip: Cover the effects on different parts of the ecosystem (soil, water, air, human health, wildlife) to provide a comprehensive answer.

 

Question 46. Categorize the solid waste and its sources.
Answer: Solid waste can be categorized by its source:

This table shows how different places and activities create various types of solid waste. Managing these wastes properly is vital for a clean environment.
In simple words: Solid waste comes from different places like homes, factories, shops, and farms, including things like food scraps, plastics, paper, and old electronics.

🎯 Exam Tip: When presenting a table, ensure the categories are clear and the examples for each source are distinct and relevant.

 

Question 47. How radioactive waste is managed? Suggest a few methods of disposal of radioactive' waste.
Answer: Managing radioactive waste involves treating, storing, and disposing of liquid, airborne, and solid waste from the nuclear industry. Here are some disposal methods:
• Limit generation: The first and most important step is to produce as little radioactive waste as possible.
• Dilute and disperse: For wastes with low radioactivity, they can be diluted and spread out.
• Delay and decay: This is a common strategy because much of the radioactivity in nuclear reactors and accelerators quickly reduces over time (short-lived).
• Concentrate and confine: For longer-lived radioactive waste, the goal is to concentrate it and contain it. This involves putting the waste in strong, corrosion-resistant containers and moving them to special disposal sites. However, the leakage of heavy metals and radionuclides from these sites can be a problem. Careful handling is necessary at every step.
In simple words: Radioactive waste is managed by making less of it, diluting it if it's not too strong, letting it decay over time, or putting strong waste in special containers deep underground.

🎯 Exam Tip: When describing management methods, focus on the 'reduce, reuse, recycle' principles adapted for radioactive materials (limit, dilute, delay, concentrate).

 

Higher Order Thinking Skills (HOTs) Questions

 

Question 1. Complete the following: (a) Smoke + _____ = Smog
Answer: (a) Smoke + Fog = Smog. Smog is a type of air pollution often seen as a thick haze.
In simple words: When smoke mixes with fog, it creates smog, which is a thick, hazy kind of air pollution.

🎯 Exam Tip: Remember that smog is a combination, and often involves smoke and fog, or other pollutants with sunlight.

 

Question 2. What is the unit of measuring ozone thickness?
Answer: The unit for measuring ozone thickness is the Dobson Unit. This unit helps scientists track changes in the ozone layer.
In simple words: Ozone thickness is measured using a unit called the Dobson Unit.

🎯 Exam Tip: Specific units are important; ensure you recall "Dobson Unit" for ozone thickness.

 

Question 3. List any four adverse effects of noise.
Answer: Four adverse effects of noise pollution are:
• High blood pressure
• Stress-related ailments
• Sleep disruption
• Hearing impairment. Noise pollution can seriously impact overall health and well-being.
In simple words: Noise can cause high blood pressure, stress, trouble sleeping, and damage our hearing.

🎯 Exam Tip: When listing adverse effects, choose distinct impacts to showcase a broad understanding of the problem.

 

Question 4. Name the scientist who discovered the ozone layer
Answer: The scientists who discovered the ozone layer were Charles Fabry and Henri Buisson. They identified this important protective layer in the Earth's atmosphere.
In simple words: Charles Fabry and Henri Buisson were the scientists who found the ozone layer.

🎯 Exam Tip: Make sure to spell the names of the scientists correctly for full marks.