Question 1

Question 9What does Eutrophication mean?

Accepted Answer

Due to use of excess fertilizers, there is leaching of nitrates and phosphates into water bodies. This causes overgrowth of aquatic plants, covering the surface of water body which further leads to increased biological oxygen demand. Therefore, the process by which the excess phosphates and nitrates lead to overgrowth of algae and other aquatic plants in a water body, depleting the oxygen of water, is called Eutrophication. It leads to death of aquatic animals due to oxygen deficiency.

Question 2

Question 10Write short notes on:Bhopal gas tragedyChernobyl disaster

Accepted Answer

Bhopal gas tragedy — The Bhopal Gas tragedy was the worst industrial accident that occurred on December 3, 1984. The accident was caused by release of 40 tonnes of methyl isocyanate (MIC) into the atmosphere from Union Carbide's pesticide factory in Bhopal, Madhya Pradesh.Nearly 35,000 to 40,000 people were killed. Most of the people affected had breathing problems. The gas affected their nervous system, people lost control of their bodies. Many pregnant women were affected and lost their baby.The blood of the victims had permanently got toxified. Methyl isocyanate also interfered severely with their reproductive ability and various plant species have suffered from chromosomal aberrations.Chernobyl disaster — The Chernobyl disaster occurred on April 26, 1986 at Chernobyl Nuclear plant in Ukraine. It was one of the worst disasters in the history of nuclear power. The main reasons for this disaster were poor plant design, incompetence and poorly designed safety measures.Whole of Western USSR and other European countries were contaminated by gamma emissions deposited in soil, meat and dairy products were contaminated. Thousands of people became exposed to Chernobyl radiation, affecting living organisms. It caused genetic disorders, variety of cancers and Leukaemia.

Question 3

Question 11Why do people in cities suffer from viral fever, allergies etc.?

Accepted Answer

The cities are more polluted due to urbanization. Industries and vehicles release a lot of smoke into the atmosphere. Construction activities lead to dust in the atmosphere. All this makes the air polluted which further leads to fever, allergies and breathing problems etc.

Question 4

Question 12What are the effects of Noise pollution?

Accepted Answer

Following are the effects of Noise pollution:Sleep disturbancesHearing lossInterference with communicationAnnoyanceHeadacheGeneral fatigueRise in blood pressureProblems with the digestive system.

Question 5

Question 1Given below are scenes, list the pollutants generated by each. How does each pollutant affect (i) environment; (ii) humans and other living beings; and (iii) materials?Picture APicture BPicture CPicture D

Accepted Answer

(a) The given picture is showing Air Pollution by Industrial emissions.Pollutants generated —Smoke (suspended particulate matter)Carbon monoxide (CO)Sulphur dioxide (SO2)Nitrogen oxides (NOx)Effects on Environment —The combination of smoke and fog leads to formation of Smog.Increase in concentration of Carbon dioxide (CO2) along with other Greenhouse gases like Methane, Nitrogen oxides (NOx), Chlorofluorocarbons and water vapour are responsible for increasing temperature causing Global warming.Due to excessive heat, water will evaporate quickly. The soil affected with erosion and devoid of vegetative cover will not retain moisture for long leading to droughts.Rising temperatures cause glaciers to melt, forming natural lakes between debris mounds. These lakes receive meltwater faster than they can drain, increasing the risk of frequent flooding.Sulphur dioxide (SO2) and Nitrogen oxides (NOx) affect the growth of plants and metabolism by destroying chlorophyll and disrupting photosynthesis.Effects on Humans and other living beings —Smoke causes Asthma, irritation of eyes and cancer.Carbon monoxide damages lungs, weakens bones, reduces the oxygen carrying capacity of blood and damages heart.In the long term air pollution causes damage to the nerves, brain, liver and kidneys.Oxides of Nitrogen (nitric oxide, nitrogen dioxide and nitrous oxide) cause acute respiratory infections, bronchitis, lowers resistance to influenza.Animals that feed on grass and plants (coated with polluted particulate matter) are affected with arsenic poisoning.Lead poisoning results in bronchitis and lack of appetite in pet animals.Effects on Materials —Soot, dust and fumes from air pollutants cause damage to the painted surfaces, fabrics and buildings.Sulphur dioxide together with moisture forms Sulphuric acid and causes corrosion of metals like steel, copper, and zinc.Sulphuric acid mist and Acid rains damage marble and limestone.Paper becomes brittle and leather undergoes disintegration by Sulphur dioxide and Acid gases.Nitrogen oxides (NOx) discolour, deteriorate and reduce the strength of textiles.(b) The given picture is of a waterbody affected by Eutrophication, showing Water Pollution.Pollutants generated —Phytoplankton and AlgaeEffects on Environment —Chemicals that are drained into the water have harmful effects on every organism that lives there.Phytoplankton and algae reduce the penetration of oxygen, light and heat into the waterbody, creating oxygen depleted zones.Algae forming a layer on top of the waterbody obstructs photosynthesis.Effects on Humans and other living beings —Most of the water organisms die due to lack of oxygen.Algae are harmful for the fishes as they contain lots of toxins. Consumption of contaminated fish makes us sick.The pathogens present in polluted water are responsible for several water borne diseases like cholera, typhoid, diarrhoea, dysentery, hepatitis, polio and jaundice.Effects on Materials —Eutrophication speeds up corrosion of metals like iron, steel, and copper. This affects pipes, boats, and underwater structures.Water often becomes green, cloudy, or even black due to excess algae and decaying organic matter. The breakdown releases foul-smelling gases like hydrogen sulphide (H2S) and ammonia.Algae and bacterial slime can form layers on surfaces affecting water treatment equipment, ship hulls, and industrial machinery.(c) The given picture shows a polluted river, indicating Water Pollution and Land Pollution.Pollutants generated —Bad smellPathogens — Bacteria, viruses, protozoa and parasites from sewage and animal waste.Effects on Environment —Water quality is deteriorated.This polluted water infiltrates down the soil and further pollutes the groundwater.Plastics and polythene bags can clog waterways, preventing proper water flow and disrupting aquatic ecosystems.When plastics break down into microplastics, they can contaminate the soil, making it difficult for plants to grow.Effects on Humans and other living beings —When plastics degrade, they release harmful chemicals into the environment, affecting human health via contaminated water and air.The pathogens from these areas enter the human body from contaminated drinking water and are responsible for several waterborne diseases.It can cause diseases in aquatic organisms, disrupting ecosystems.Effects on Materials —Plastic waste may cause long-term damage like staining or corrosion.As plastics break down into microplastics, they can embed in materials such as textiles, construction materials, or even concrete, potentially weakening them or altering their properties.Plastics can leach harmful additives and heavy metals into water and soil. These chemicals can contaminate other materials, especially food, water supplies, and packaging.(d) The given picture is of Nuclear Reactors, indicating Radioactive pollution.Pollutants generated —Radioactive particlesFuel elementsCoolantsWastewaterEffects on Environment —Radioactive wastes like used fuel and coolants may escape into the surroundings. Inert gases escape as vapours and pollute the environment.The radioactive waste emitted during nuclear tests makes the surrounding materials radioactive.Radioactive particles are carried away to distant places by wind and brought down by rain. When these rain drops fall to the ground, they cause soil pollution.When wastewater from research laboratories reach the water bodies through the sewers, they cause water pollution.The high level products of nuclear wastes remain in the environment for several hundred years.Other radioactive threats to the environment are the accidents connected with the activities of nuclear reactors, nuclear powered vessels and satellites, etc.Effects on Humans and other living beings —The X-rays pass through genetic cells and affect the chromosomes, resulting in mutations.Genetic Variation: The damage caused by radiations is often seen in the offsprings and may be transmitted to many generations.Somatic Variation: Short term exposures to radiation can cause damage to organs of the body. The harm done by them includes breast cancer, thyroid cancer, lung cancer and brain cancer, sterility and defective eyesight.Other living beings such as animals and aquatic life also faces the consequences of improper radioactive waste handling.Effects on Materials —Radioactive particles can bind to dust, soil, water, and organic matter, making them hazardous.Corrodes and weakens building structures over time.Contaminated water, food, or raw materials can pose risks to health and safety, even in small amounts.Materials contaminated by radioactive waste must be stored or disposed of with extreme care because they remain hazardous for years or even centuries.

Question 6

Question 6In what way does soil pollution affect human beings?

Accepted Answer

Soil pollution affects human beings in the following ways-Soil contains many pathogenic bacteria, viruses and intestinal worms which are transmitted to man by the consumption of fruits and vegetables. These pathogens cause various types of diseases.Radioactive fallout on vegetation is the source of radioisotopes which enter the food chain through the grazing animals. Some of these radioisotopes cause abnormalities.Use of animals and human excreta as manure pollutes the soil. Excreta contains pathogens that contaminate the soil and vegetable crops and affect the health of human beings.

Question 7

Question 7A landfill was reclaimed and sturdy plants were grown on it instead of crops or fruit trees. Why?

Accepted Answer

This is because landfills contain toxic substances like heavy metals, chemicals, and non-biodegradable waste that can remain in soil for many years. Crops or fruit trees grown on such soil could absorb these toxins, making the food produced unsafe for human or animal consumption. So, by planting sturdy plants, we can limit the spread of pollutants to surrounding areas, and they may even absorb some pollutants over time, slowly improving soil health.

Question 8

Question 1(d)With the help of a well labelled diagram explain how the accumulation of toxic substances increases as we move up the food chain.

Accepted Answer

Below diagram shows the increase in accumulation of toxic substances as we move up the food chain:Biomagnification means increasing the concentration of various toxic substances along the food chain. Toxic substances at the level of primary producers get concentrated at each trophic level as they move up the food chain. The phenomenon of concentrated toxic deposition at the higher trophic level is known as bioaccumulation.For example, if there are traces of toxic chemicals in water, then their concentration in algae will be much higher. When fish eat the algae, the concentration of toxins will increase further. Therefore, accumulation of a small amount of toxic chemicals in water can have a serious impact on the fish that live in it.

Question 9

Question 2(a)State any two effects each of soil pollution on human beings and environment.

Accepted Answer

Effects of soil pollution on human beings are -Soil contains many pathogenic bacteria, viruses and intestinal worms which are transmitted to man by the consumption of fruits and vegetables. These pathogens cause various types of diseases.Radioactive fallout on vegetation is the source of radioisotopes which enter the food chain through the grazing animals. Some of these radioisotopes cause abnormalities.Effects of soil pollution on environment are-Nitrogenous fertilisers produce toxic concentration of nitrate and nitrite in the leaves.Land and soil pollution is responsible for loss of fertility and productivity of soil.

Question 10

Question 2(d)State with examples the effects of radiations on the human beings and environment.

Accepted Answer

Example of radioactive accidentThere was a radioactive accident in 1986 in Chernobyl in the Ukraine. On 26th April, 1986, a reactor at the nuclear power complex at Chernobyl exploded.There was a massive steam explosion. The core of the reactor combined with water to produce hydrogen which exploded blowing toxic radioactive gases into the air. There were numerous fires. The Chernobyl accident is considered as the most disastrous nuclear power plant accident, both in terms of cost and casualties.Due to the accident, 237 people suffered from acute radiation sickness, of whom 31 died within the first three months. After the disaster, four square kilometers of pine forest near the reactor turned reddish brown and died, earning the name of the 'Red Forest'. Some animals in the worst hit areas died or stopped reproducing.Effects of radiations on human healthRadiations affect living organisms. They cause harmful changes in the body cells and at genetic level. Some impacts of radiations on human body are-Genetic variations — The damage caused by radiations is often seen in the offsprings and may be transmitted to many generations.Somatic variations — Short term exposures to radiation can cause damage to organs of the body. The harm done by them includes breast cancer, thyroid cancer, lung cancer and brain cancer, sterility and defective eyesight.Effects of radiations on the environmentRadiations emitting from radioactive materials and the disposal of radioactive wastes cause pollution and damage the environment.The high level products of nuclear wastes remain in the environment for several hundred years. Other radioactive threats to the environment are the accidents connected with the activities of nuclear reactors, nuclear powered vessels and satellites etc.

Question 11

Question 2Which is the most visible affect of pollution on human beings in your city? What are the causes and possible remedies?

Accepted Answer

One of the most visible effects of pollution on human beings in my city is the deterioration of air quality. The main causes for the deterioration of air quality are:Industrial emissions — This includes the burning of fossil fuels and release of pollutants into the air.Vehicle emissions — Emissions from cars, trucks and motorcycles contribute significantly to air pollution.Agricultural practices — Burning crop residues and the use of chemical fertilizers and pesticides add to the pollution.Household pollution — This is due to the use of solid fuels like coal, wood and biomass for cooking and heating purposes.The possible remedies to improve the quality of air are:Transition to clean energy sources like solar and wind power to reduce dependence on fossil fuels.Improve industrial practices by implementing stricter emission control measures and promoting cleaner production techniques.Promote public transportation systems and encourage the adoption of electric vehicles to reduce vehicular emissions.Encourage sustainable alternatives to crop residue burning, such as recycling for energy production or composting.Raise awareness and promote behavioral changes in waste management and reduction of polluting substances.Strengthen environmental regulations, ensure compliance, and impose penalties for violators.

Question 12

Question 3Northern India is enveloped in smog in the month of November. List the causes for the same.

Accepted Answer

Northern India is enveloped in smog in the month of November because of the following causes:Crop Residue Burning — In Punjab and Haryana, farmers often burn crop residues after harvesting to prepare the fields for the next crop. This releases a significant amount of smoke and particulate matter into the air.Stubble Burning — The burning of leftover crop residue in the fields is a common practice after rice harvesting and contributes to the smog problem in northern India.Diwali Celebrations — Diwali is celebrated with fireworks and firecrackers, which releases a large amount of pollutants, including particulate matter and toxic chemicals into the atmosphere.Industrial Emissions — The industrial activities and factories in the region release pollutants like sulphur dioxide, nitrogen dioxide and particulate matter into the air, contributing to the smog formation.Vehicular Emissions — The high number of vehicles in the region contribute to air pollution through exhaust emissions.

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