Environmental Issues

Class 12 | Pure Science — Zoology | Chapter 13

Class 12 Unit 13 Pure_Science

ENVIRONMENTAL ISSUES

"Environment is my Prime Teacher" — Masanobu Fukuoka

Chapter Outline

• 13.1 Pollution
• 13.2 Air Pollution
• 13.3 Water Pollution
• 13.4 Noise Pollution
• 13.5 Agrochemicals
• 13.6 Biomagnification
• 13.7 Eutrophication
• 13.8 Organic Farming and its Implementation
• 13.9 Solid Waste Management
• 13.10 Ecosan Toilets

Learning Objectives

• Gain knowledge about our environment and its importance.
• Get to know about the effects and after effects of human activities on climate and ecosystem.
• Know about eco-friendly practices for pollution mitigation.
• Acquire insights into solutions to environmental problems.
• Understand the need for peoples' participation in environmental protection.
• Understand the importance of clean environment.

A clean environment is very necessary to live a peaceful and healthy life. But our environment is getting dirty day by day because of our negligence. Earth is currently facing a lot of environmental concerns like air pollution, water pollution, and noise pollution, global warming, acid rain, biomagnification, eutrophication, deforestation, waste disposal, ozone layer depletion and climate change. Over the last few decades, the exploitation of our planet and degradation of our environment have gone up at an alarming rate. As our actions have not been in favour of protecting this planet, we have seen natural disasters striking us more often in the form of flash floods, tsunami and cyclones.

"Every individual should be environmentally aware, regardless of whether they work with environmental issues or not."

13.1 Pollution

Pollution is any undesirable change in the physical, chemical and biological characteristics of the environment due to natural causes and human activities. The agents which cause pollution are called pollutants. Pollution is classified according to the types of environment that is affected. They are mainly air, water and soil pollution.

13.1.1 Classification of Pollutants

In terms of ecosystem, pollutants can be classified into two basic groups: Nondegradable and Degradable. Based on the time taken to breakdown into their ingredients, degradable pollutants are classified as rapidly degradable (non persistent) and slowly degradable (persistent).

a) Rapidly Degradable or Non-Persistent Pollutants

These can be broken down by natural processes. Domestic sewage and vegetable waste are examples of such pollutants.

b) Slowly Degradable or Persistent Pollutants

These are pollutants that remain in the environment for many years in an unchanged condition and take decades or longer to degrade, as in the case of DDT.

c) Non-Degradable Pollutants

These cannot be degraded by natural processes. Once they are released into the environment, they are difficult to be eliminated and continue to accumulate (biomagnification). Toxic elements like lead, mercury, cadmium, chromium and nickel are such common pollutants.

13.2 Air Pollution

Earth is surrounded by a gaseous envelope which is called atmosphere. The gaseous blanket of the atmosphere acts as a thermal insulator and regulates the temperature of the earth by selectively absorbing the UV rays of solar radiation. The adverse effects of pollution include depletion of Ozone by Chlorofluorocarbons or CFCs, used as refrigerants and global warming by elevated CO₂ (industries, deforestation, and partial combustion). The alterations or changes in the composition of the earth's atmosphere by natural or human activities (anthropogenic factors) are referred to as Air Pollution.

Pollutants include the abundant presence of solid, liquid or gaseous substances produced by human or natural activity. The nature and concentration of a pollutant determines the severity of detrimental effects on organisms and human health. Along with atmospheric factors (humidity, precipitation, wind, air currents, altitude) prevailing at a place and time, its effects can be far reaching and catastrophic.

Air Pollutants Include:

• Discharge of dusts or particulate matter (PM: 2.5 µm)
• Discharge of gases (Sulphur dioxide, Nitrogen dioxide, Carbon monoxide, Carbon dioxide)

Carbon monoxide is produced mainly due to incomplete combustion of fossil fuels. Automobiles are major causes of Carbon monoxide pollution in large cities and towns. Automobile exhausts, fumes from factories, emission from power plants, forest fires and burning of fire-wood contribute to Carbon monoxide pollution.

With rapid urbanization, major amount of carbon dioxide and sulphur dioxide (SO₂) is released in the atmosphere. From automobiles, aeroplanes, power plants and other human activities involving the burning of fossil fuels (coal, oil etc.), Carbon dioxide (CO₂) is the main pollutant that is leading to global warming.

Nitrogen oxides are also major air pollutants. Fossil fuel combustion and automobile exhausts are the source of nitrogen oxides. Sulphur dioxide and nitrogen oxides are the major causes of acid rain.

Particulate matters are tiny particles of solid matter suspended in a gas or liquid. Combustion of fossil fuels, fly ash produced in thermal power plants, forest fires, asbestos mining units, cement factories are the main sources of particulate matter pollution.

13.2.1 Sources

The Main Sources of Air Pollution

• Transport sources: Cars, buses, airplanes, trucks, trains
• Stationary sources: Power plants, incinerators, oil refineries, industrial facilities, and factories
• Area sources: Agricultural wood or stubble burning, fireplaces
• Natural sources: Wind-blown dust, wildfires, volcanoes

13.2.2 Effects of Air Pollution

• Affects all organisms as they depend on the atmosphere for respiration.
• Causes irritation in the throat, nose, lungs and eyes. It causes breathing problems and aggravates existing health conditions such as emphysema and asthma.
• Contaminated air reduces the body's defense mechanism and decreases the body's capacity to fight other infections in the respiratory system.
• Frequent exposure to polluted air increases the risk of cardiovascular diseases. Breathing air that is filled with fine particulate matter can induce hardening of the arteries, triggering cardiac arrhythmia or even a heart attack.
• People who exercise outdoors can sometimes be susceptible to adverse effects of air pollution because it involves deeper and faster breathing. Hence it is advisable to walk or jog in the mornings in places with ample tree cover.
• Gas leaks can be lethal or affect the quality of air in the affected area.
• CO in the atmosphere interferes with O₂ transport since haemoglobin has greater affinity for carbon monoxide. At low concentration it causes headache and blurred vision. In higher concentration, it can lead to coma and death.

Do You Know?

Sameer, an App provides hourly updates on the National Air Quality Index (AQI) published by CPCB.

13.2.3 Other Notable Effects of Air Pollution

Smog

Smog is a type of air pollution caused by tiny particles in the air. The word comes from a mixture of the words smoke and fog. Today, smog generally refers to photochemical smog, which is created when sunlight reacts with nitrogen oxides and volatile organic compounds found in fossil fuel emissions from automobiles, factories, and power plants. These reactions create ground level ozone and particulate matter, reducing visibility. Smog can make breathing more difficult, especially for people with asthma. Smog also affects plants and animals. It damages crops as well as causes health problems in pets, farm animals and human beings. Smog has also been known to cause corrosive damage to buildings and vehicles.

Peroxyacetyl nitrate (PAN) is a secondary pollutant present in photochemical smog. It is thermally unstable and decomposes into peroxyethanol radicals and nitrogen dioxide gas causing eye irritation.

Global Warming

Increase in the concentrations of greenhouse gases such as CO₂, methane, nitrous oxide, CFCs, and ozone causes greenhouse effect, warming of the earth, resulting in sea level rise, submerging of islands and sea shores of various parts of the world.

Ozone Depletion

Thinning of the stratospheric ozone layer is known as ozone depletion. Such depletion causes the 'ozone hole', resulting in poor screening of the harmful UV rays and increase in incidences of skin cancer. Some of the common agents that deplete ozone are CFCs.

Acid Rain

Acid rain is a form of precipitation that contains acidic components, such as sulphuric acid or nitric acid. It damages trees, crops and harms marine animals (coral reefs) and induces corrosion.

13.2.4 Control of Air Pollution

• Trees are the best remedy for urban particulate and gaseous pollution.
• Forests act as carbon sinks and lungs of the planet.
• Catalytic converters in vehicles help to reduce polluting gases drastically.
• Diesel exhaust filters in automobiles cuts particulates.
• Electrostatic precipitators reduce release of industrial pollutants.
• Cost effective air pollution treatment systems like indoor plants and high performance biofilters can improve indoor air quality.

Box Item

The Taj Mahal, a UNESCO world heritage site, is facing deterioration and damage by industrial gases due to several industrial units around Agra. The white marble has decolorized to yellow.

13.2.5 Legal Protection

• The Air (Prevention and Control of Pollution) Act was enacted in 1981 and amended in 1987 for the prevention, control and abatement of Air pollution in India.
• Traffic Emissions Standards: The Government has decided to enforce Bharat Stage VI norms from 2020.
• The Green Bench and the National Green Tribunal (NGT) give judicial safeguard to environmental protection.

Steps Taken by the Central and the State Governments in India

• Road traffic rationing, encourage public transport, carpooling
• Increase green cover alongside roads (planting avenue trees)
• Promoting Swachh Bharat Abhiyan
• Enactment and Enforcement of stricter environmental laws
• Maintenance of air standards by proper enforcement and monitoring
• Reducing carbon emissions
• Encourage use of renewable energy
• Limiting the sale of firecrackers and developing eco-friendly crackers
• Make Environmental Impact Assessment mandatory

Air Quality Index (AQI) is a number used by government agencies to communicate to the public how polluted the air is at a given time.

Do You Know?

Average human consumption of Oxygen per day = 550 L
Cost of 2.75 L Oxygen cylinder = ₹6500
Cost of 550 L of oxygen from tree = ₹13,00,000
Oxygen production by one healthy tree per year = 1,00,375 L
Cost of 1,00,375 L of oxygen from one tree/year = ₹23,72,50,000

Air Quality Index (AQI) Table

AQI	Air Pollution Level	Colour
0 to 50	Good	Dark Green
51 to 100	Moderate	Light Green
101 to 150	Unhealthy for Sensitive Groups	Yellow
151 to 200	Unhealthy	Maroon
201 to 300	Very Unhealthy	Red
301 onwards	Hazardous	Dark Red

13.3 Water Pollution

13.3.1 Quality of Water

Water is essential for life and for the health of the environment. As a valuable natural resource, it comprises marine, estuarine, freshwater (river and lakes) and groundwater environments that stretch across coastal and inland areas. Water has two dimensions that are closely linked: quantity and quality. Water quality is commonly defined by its physical, chemical, biological and aesthetic (appearance and smell) characteristics. A healthy environment is one in which the water quality supports a rich and varied community of organisms and protects public health.

13.3.2 Water Pollution

Water pollution occurs when there is a change in the chemical, physical or biological quality of water that has harmful effects on living organisms that consume it or live in it. Water pollution adversely affects water bodies due to the large amounts of natural or man-made materials let into it. When it becomes unfit for its intended use, water is considered polluted.

13.3.3 Sources of Water Pollution

Even though water bodies or sources can be polluted by natural causes, water pollution is usually caused by human activities. There are three main types of sources: point sources, non-point sources, leaks and spills.

Point Sources

Discharge of pollutants at specific locations through pipelines or sewers into the water body. Factory effluents, sewage, underground mines, oil wells, oil tankers and agriculture are common point sources.

Non-Point Sources

Sources that cannot be traced to a single site of discharge like acid rain, dumping of the plastics in water bodies, agriculture chemical run off are common examples.

Leaks and Spills

This occurs mostly due to ship collision, off shore oil rigs, oil leakages and discharges into sea.

Sources of water pollution can also be classified in three ways. They are municipal wastes, industrial wastes, and agricultural wastes.

1. Municipal waste water is from homes and commercial establishments.
2. Industrial discharge (effluents) may contain varieties of compounds such as heavy metals (cadmium, chromium, lead), and organic or inorganic chemicals containing waste water, sometimes in toxic concentrations. These discharges can affect temperatures of the water bodies as well as dissolved oxygen level.
3. Agricultural wastes include fertiliser and pesticide runoff from agricultural fields, food processing waste, tree and saw dust from logging operations and bacteria from sewage or livestock operations.

Water pollutants reach water bodies like rivers, streams and the marine system by precipitation, run off and the groundwater by seepage or percolation.

13.3.4 Effect of Water Pollution on Ecosystems

1. Destruction of Ecosystems

Ecosystems, especially aquatic systems, can be severely affected or destroyed by water pollution. Water pollutants affect existing niches and habitats and the survival of organisms. Soil fertility is affected and the system becomes uninhabitable.

2. Disruption of Food Chains

Water pollution disrupts the natural food chains as well as food webs. Pollutants such as lead and cadmium are taken up by primary consumers where they can be lethal or get stored. Later, when these animals are consumed by secondary consumers, the food chain can get disrupted at any trophic level or result in enhanced concentration of these pollutants (biomagnification). Hot water from industries when released into the water bodies affects aquatic density and diversity.

13.3.5 Effect of Water Pollution on Organisms

1. Water pollution can be lethal to aquatic organisms and others that depend on these water bodies. Accidental oil spills from tanker ships can cause substantial environmental damage. Oil spreads on the water surface, prevents the entry of light and oxygen into the water. This increases BOD and COD, resulting in mass death of organisms and degradation of water quality. It also clogs fish gills and the feathers of aquatic birds.

Box Item

On January 28, 2017, two cargo ships collided off the Ennore coast in Chennai causing oil to spill into the sea. Due to wave action and the southern current, the spill spread over to 34 kilometre down south affecting the coast. Beach sand also got spoiled by the oil sludge. It took more than a thousand volunteers to clean the oil sludge.

2. Humans and other organisms can get affected by diseases such as hepatitis and typhoid by consuming contaminated water and food. Excess of fluoride in drinking water causes fluorosis. In many poor nations, outbreak of water borne diseases and epidemics are a result of contaminated water and poor or absence of water treatment processes.

3. Water pollution can cause eutrophication due to nutrient enrichment. This causes algal blooms which affect the quality of water bodies. Red tides, if occur, can be lethal to aquatic organisms.

13.3.6 Control Measures

1. Right to clean water is a fundamental right under the Indian Constitution (Article 21).
2. Water (Prevention and Control of Pollution) Act, 1974, sections 17 to 40 prohibit the pollution of a stream or well by disposal of polluting matter.
3. The Central or State Pollution Control Boards have the power to advise the central/state government on various matters concerned with the prevention and control of pollution of water.
4. The Ministry of Environment, Forest and Climate Change (MoEFCC) is the nodal agency of the Central Government for the planning, promotion, co-ordination and for overseeing the implementation of India's environmental and forestry policies and programmes.
5. National river conservation plan (NRCP) was enacted in 1995 to improve the water quality of the rivers, which are the major fresh water resources in our country. This important assignment taken up under the NRCP includes:
   • To capture the raw sewage flowing into the river through open drains and divert them for treatment.
   • Setting up sewage treatment plants for treating the diverted sewage.
   • Construction of low-cost sanitation toilets to prevent open defecation on river banks.

Prevention

• Regulate or control of pollutants discharge at the point of generation.
• Wastewater can be pretreated by scientific methods before discharge to municipal treatment sources.
• Setting up of Sewage Treatment Plants (STP) and Effluent Treatment Plants (ETP).
• Regulate or restrict the use of synthetic fertilisers and pesticides.
• Public awareness and peoples' involvement is essential.

Box Item — Assessment by CPCB

The number of polluted stretches in India's rivers has increased to 351 from 302 (in 2006), and the number of critically polluted stretches where water quality indicators are the poorest has gone up to 45 from 35. (Source: The Hindu, 17 September, 2018)

Case Study — Namami Gange

Namami Gange (National Mission for Clean Ganga) Programme is an Integrated Conservation Mission approved as the 'Flagship Programme' of the Union Government in June 2014 with a budget outlay of 20,000 crores to accomplish the twin objectives of effective abatement of pollution, conservation and rejuvenation of River Ganga.

13.4 Noise Pollution

Sound that is unwanted and undesirable or can disrupts one's quality of life is called Noise. When there is lot of 'noise' in the environment, it is termed as Noise Pollution. The intensity of noise is measured in decibels (dB).

13.4.1 Sources of Noise Pollution

Vehicle engines, air horns, audio video systems, trains, low flying aircrafts, factory machines, sirens, motors, drillers and crushers, compressor machines, crackers, explosives, modern supersonic transports are the common sources of noise pollution. The threshold of pain is about 120 dB. World Health Organization has proposed that noise must be recognized as a major threat to human well-being. This is applicable for all living organisms.

13.4.2 Effect of Noise Pollution

• According to the USEPA (United States Environmental Protection Agency) there are direct links between noise and health. Heart disease, high blood pressure, stress related illness, sleep disruption, hearing loss (deafness), and productivity loss are the problems related to noise pollution.
• Increased stress and tension, nervousness, irritability, anxiety, depression and panic attacks.
• Peptic ulcer, severe head ache, memory loss.
• Marine animals are affected by noise pollution from offshore activities and port activities.
• Fire crackers frighten animals. Birds are often affected by increased air traffic.

13.4.3 Control

• Planting trees in and around noise sources is an effective solution for noise pollution as plants are known to absorb noise and bring down sound levels.
• Regular servicing and tuning of automobile engines can effectively reduce noise pollution by vehicles and machinery.
• Workers should be provided with ear plugs and earmuffs at work sites that generate high noise levels.
• Lubrication of machinery and regular servicing minimizes noise levels.
• Regulations should be imposed to restrict the usage of loudspeakers in crowded areas and public places.

13.4.4 Legal Protection

Article 48 A and Article 51 A of the Constitution of India, Noise Pollution (Regulation and Control) Rules 2000, and Tamil Nadu State Environment Policy 2017 are some of the legal relief from noise pollution. According to Noise Pollution (Regulation and Control) Rules, 2000, the permissible limit of noise in areas categorized as commercial is 65 decibels (dB) during day and 55 dB during night.

13.5 Agrochemicals

Chemicals which are used in agriculture for growth of plants and pest control are called agrochemicals or agrichemicals. Overuse of agrochemicals have been observed to generate residues that cause nutrient imbalance, and:

• May kill beneficial bacteria and soil organisms.
• Can cause eutrophication in water bodies.
• Affect aquatic animals and their productivity.
• Pesticide containing water, even in trace quantities is unfit for human consumption.
• Particles (aerosols) and residues of these chemicals cause air pollution.
• Inhalation of contaminated air can cause respiratory problems.
• Consumption can lead to poisoning, side effects and after effects.
• Chemicals can cause skin rashes and irritation of eyes.
• Many of these chemicals are reported to be carcinogenic.
• They can trigger hormonal disorders and neurotoxicity.
• Beneficial insects and animals can be affected.

Box Item

1. Mosquito Repellents: DEET (n,n-diethylmetatoluamide) and allethrin used in mosquito coils may cause itching, burning, tingling sensation or numbness.

2. Colony collapse syndrome in Honey bees due to pesticides/herbicides can lead to destruction of hives and lower agricultural productivity. Remember bees are Nature's best pollinators!

13.6 Biomagnification

Food chains are components of all ecosystems. Producers and consumers form trophic levels in a chain through which energy flow is carried out by the process of eating and being eaten. Usage, storage and transformation of food and biomolecules by metabolism are a normal process. Degradation or breakdown is an essential part of any food chain and hence all naturally occurring substances are degradable.

When non-degradable substances enter the food chain, they do not get metabolized or broken down or expelled and instead get transferred up the trophic levels of the food chain. During this process, they show an increase in concentration which is referred to as biomagnification. This results in increased toxicity and may even be lethal. This phenomenon is well established for mercury and DDT.

Biomagnification of DDT in an aquatic food chain shows that the concentration of DDT is enhanced at successive trophic levels.

13.7 Eutrophication

When run-off from land containing nutrients reaches water bodies like lakes, it results in dense growth of plant life. This phenomenon is called Eutrophication. Natural aging of lakes also leads to nutrient enrichment of its water. In a lake, the water is cold and clear (oligotrophic stage), supporting little life. With time, streams draining into the lake introduce nutrients such as nitrates and phosphates, which encourage the growth of aquatic organisms. Aquatic plants and animal life grow rapidly, and organic remains begin to be deposited on the lake bottom (mesotrophic stage).

Pollutants from anthropogenic activities like effluents from the industries and homes can radically accelerate the aging process. This phenomenon is known as Cultural or Accelerated Eutrophication. Nutrients stimulate the growth of algae, water hyacinth and can cause clogging of canals, rivers and lakes as well as displacing native plants. It causes unsightly foam and unpleasant odours, and deprives the water of dissolved oxygen.

13.7.1 Integrated Wastewater Management

Wastewater or sewage originates from domestic waste waters, industrial wastes and animal wastes. Realizing the importance of clean potable water, the Government passed the Water (Prevention and Control of Pollution) Act in 1974, which made it mandatory to treat wastewater in treatment plants. The main objective of a wastewater treatment process is to reduce organic and inorganic components in wastewater to a level that it no longer supports microbial growth and to eliminate other potentially toxic materials.

Microorganisms mainly bacteria and some protozoa play an essential part in the treatment of sewage to make it harmless. Sewage contains pathogenic bacteria. These bacteria must be destroyed in order to prevent the spread of diseases.

Sewage treatment is usually performed in the following three stages:

Primary Treatment

Primary treatment involves the physical removal of solid and particulate organic and inorganic materials from the sewage through filtration and sedimentation. Floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.

Secondary Treatment or Biological Treatment

The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into floc (masses of bacteria associated with fungal filaments to form mesh like structures). While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (Biochemical oxygen demand or Biological oxygen demand). BOD refers to the amount of the oxygen that would be consumed, if all the organic matter in one litre of water were oxidized by bacteria. The sewage water is treated till the BOD is reduced. The greater the BOD of the waste water more is its polluting potential.

Once the BOD of sewage water is reduced significantly, the effluent is then passed into a settling tank where the bacterial "flocs" are allowed to sediment. This sediment is called activated sludge. A small part of activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, the bacteria which grow anaerobically, digest the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and CO₂. These gases form biogas and can be used as a source of energy.

Tertiary Treatment

Tertiary treatment is the final process that improves the quality of the waste water before it is reused, recycled or released into natural water bodies. This treatment removes the remaining inorganic compounds and substances, such as nitrogen and phosphorus. UV is an ideal disinfectant for wastewater since it does not alter the water quality except for inactivating microorganisms. UV is a chemical-free process that can completely replace the existing chlorination system and also inactivates chlorine-resistant microorganisms like Cryptosporidium and Giardia.

Case Study

Auroville, located in South India near Puducherry has been experimenting with natural wastewater recycling systems (Decentralized Waste Water Treatment System (DEWATS)). Such treatment plants have now also been implemented in Aravind Eye Hospital, Puducherry (Root Zone Wastewater Treatment (RZWT)) and the Chennai Mathematical Institute, Siruseri IT Park, Chennai.

13.8 Organic Farming and Its Implementation

It is a method of farming system which primarily aims at cultivating the land and raising crops in such a way, so as to keep the soil alive and in good health by use of organic wastes (crop, animal and farm wastes, aquatic wastes) and other biological materials along with beneficial microbes (biofertilizers) to release nutrients to crops for increased sustainable production in an eco-friendly pollution free environment.

13.9 Solid Waste Management

Every day, tonnes of solid wastes are disposed off at landfill sites. This waste comes from homes, offices, industries and various other agricultural related activities. These landfill sites produce foul smell if waste is not stored and treated properly. When hazardous wastes like pesticides, batteries containing lead, cadmium, mercury or zinc, cleaning solvents, radioactive materials, e-waste and plastics are mixed up with paper and other scraps and burnt, they produce gases such as dioxins. These gases are toxic and carcinogenic. These pollute the surrounding air, ground water and can seriously affect the health of humans, wildlife and our environment.

Table 13.1 — Major Sources of Solid Waste

Waste Category	Source
Residential	Food wastes, plastics, paper, glass, leather, cardboard, metals, yard wastes, ashes, tires, batteries, old mattresses
Industrial	Packaging wastes, ashes, chemicals, cans, plastics, metal parts
Commercial	Thin and thick plastics, food wastes, metals, paper, glass, wood, cardboard materials
Institutional	Wood, paper, metals, cardboard materials, electronics
Construction and Demolition	Steel materials, concrete, wood, plastics, rubber, copper wires, dirt and glass
Agriculture	Agricultural wastes, spoiled food, pesticide containers
Biomedical	Syringes, bandages, used gloves, catheter, urine bags, drugs, paper, plastics, food wastes, sanitary napkins and diapers, chemicals
E Waste	Electronic items like used TVs, transistors, tape recorders, computer cabinets, mother boards, CDs, cassettes, mouse, wires, cords, switches, chargers

Box Item — G. Nammalvar

G. Nammalvar was a supporter and expert of organic farming. He was an agricultural scientist, environmental activist celebrated for his work on spreading Ecological farming and Organic farming. He was against the use of chemical fertilisers and pesticides. He trained hundreds of farmers in natural farming. Nammalvar was the author of several Tamil and English books on natural farming, pesticides and fertilisers. He founded the Nammalvar Ecological Foundation for Farm Research and Global Food Security Trust or simply Vaanagam at Karur, Tamilnadu. He developed social forest at Ammankurai and the Kolunji Ecological Farm in Pudukottai. He and his friends made a 10 acre barren land into fertile cultivable land in the dry Pudukottai district. He planted 52 varieties of trees in the same waste land extending in 20 acres. His organization 'Kudumbam' preserves and regenerates hundreds of native flora and fauna, in order to ensure a sustainable livelihood.

Box Item — Dr. Sultan Ahmed Ismail

Dr. Sultan Ahmed Ismail is an Indian soil biologist and ecologist from Tamil Nadu. His work has centered on techniques for recycling biodegradable waste into fertiliser using varieties of earthworms, and on soil bioremediation. Dr. Ismail received a Doctor of Science in Zoology from the University of Madras for his research on the role of earthworms in soil ecology and waste management. He works on vermicomposting as a sustainable ecological practice. He has been instrumental in introducing as well as spreading awareness on environmental issues, solid waste management, vermicomposting, organic farming, vermitech and waste management to several educational institutions, industries and organic farmers in India and abroad.

Solid Waste management includes the activities and actions required to manage waste from its inception to its final disposal. This includes the collection, transport, treatment and disposal of waste, together with monitoring and regulation of the waste management process. It is all about how solid waste can be changed and used as a valuable resource.

Case Study — Corporation of Chennai

The Corporation of Chennai looks after clearance and management of solid waste in Chennai. Every day around 5400 Metric Tonnes (MT) of garbage is collected from the city. Door to door collection of garbage is done in most zones apart from sweeping, collecting, and storing the waste in the specified bins. At present garbage generated in Chennai is dumped at two sites. Proposals are there for remediation of the existing landfill or scientific closure and to have integrated waste processing facilities with waste to energy plants as one of the components at the existing Kodungaiyur and Perungudi sites.

13.9.1 Waste Management Practices

• a) Source segregation
• b) Composting: 1. Aerobic   2. Anaerobic
• c) Vermicomposting
• d) Biogas generation
• e) Incineration

13.9.2 Radioactive Waste

Radioactive wastes are generated during various operations of the nuclear power plant. Radioactive waste can be in gas, liquid or solid form, and its level of radioactivity can vary. The waste can remain radioactive for a few hours or several months or even hundreds of thousands of years. Depending on the level and nature of radioactivity, radioactive wastes can be classified as exempt waste, Low and Intermediate level waste and High-Level Waste.

Radioactive Waste Management

Radioactive waste management involves the treatment, storage, and disposal of liquid, airborne, and solid effluents from the nuclear industry.

Do You Know?

The Three Mile Island (Pennsylvania, United States), Chernobyl (Pripyat, Ukraine) and Fukushima Daiichi (Okuma, Japan) are nuclear disasters the world has seen in the recent period.

Methods of Disposal of Radioactive Wastes

1. Limit Generation: Limiting the generation of waste is the first and most important consideration in managing radioactive wastes.
2. Dilute and Disperse: For wastes having low radioactivity, dilution and dispersion are adopted.
3. Delay and Decay: Delay and decay is frequently an important strategy because much of the radioactivity in nuclear reactors and accelerators is very short lived.
4. Concentrate and Confine: Concentrating and containing is the objective of treatment activities for longer-lived radioactivity. The waste is contained in corrosion resistant containers and transported to disposal sites. Leaching of heavy metals and radionuclides from these sites is a problem of growing concern.

Control and Management — Three Ways to Manage Nuclear Wastes

• Spent Fuel Pools: The spent fuel discharged from the reactors is temporarily stored in the reactor pool. The spent fuel rods are used in stored cooling ponds. They protect the surroundings from radiation and absorb the heat generated during radioactive decay.
• Vitrification Method: This prevents reaction or degradation of nuclear waste for extended periods of time and encased in dry cement caskets.
• Geological Repositories: A deep geological repository is a nuclear waste repository excavated deep within a stable geologic environment. It is suited to provide a high level of long-term isolation and containment without future maintenance.

In India at Tarapur and Kalpakkam, a wet storage facility of Spent Fuel is the main mode of storage.

13.9.3 Medical Waste

Any kind of waste that contains infectious material generated by hospitals, laboratories, medical research centers, pharmaceutical companies and veterinary clinics are called medical wastes. Medical wastes contain body fluids like blood, urine, body parts and other contaminants, culture dishes, glasswares, bandages, gloves, discarded needles, scalpels, swabs and tissues.

Management

The safe and sustainable management of biomedical waste is the social and legal responsibilities of people working in healthcare centers.

Waste disposal: Involved by incineration, chemical disinfection, autoclaving, encapsulation, microwave irradiation are methods of waste disposals. Final disposal includes landfill and burying as per norms inside premises.

13.9.4 E-Waste

Electronic waste or e-waste describes discarded electrical electronic devices as well as any refuse created by discarded electronic devices and components and substances involved in their manufacture or use. Their disposal is a growing problem because electronic equipment frequently contains hazardous substances. In a personal computer, for example, there may be lead (Pb) in the cathode ray tube (CRT) and soldering compound, mercury (Hg) in switches and housing, and cobalt (Co) in steel components, among other equally toxic substances. E-wastes are basically PCB (Polychlorinated biphenyl) based, which are non-degradable.

Used electronics which are destined for reuse, resale, salvage, recycling, or disposal are also considered e-waste. Unauthorised processing of e-waste in developing countries can lead to adverse human health effects and environmental pollution. Recycling and disposal of e-waste may involve significant risk to the health of workers and communities in developed countries and great care must be taken to avoid unsafe exposure in recycling operations and leaking of materials such as heavy metals from landfills and incinerator ashes.

13.9.5 Plastic Waste — Solutions and Remedies

Plastics are low molecular weight organic polymers that are non degradable in the natural environment. They are used in several items, including cars, bulletproof vests, toys, hospital equipment, carry bags and food containers. Packaging materials used in supermarkets, retail outlets, manufacturing industries, households, hotels, hospitals, restaurants and transport companies are major contributors to plastic waste generation. Plastic waste constitutes a major part of municipal solid waste.

Box Item — Remedies

'4R' mantra — Refuse, Reduce, Reuse and Recycle — is the best available remedy for plastic waste pollution.

Tamil Nadu State government successfully implemented the ban on single use plastics from 1st January 2019.

13.10 EcoSan Toilets

About 150 liters of wastewater at an average is generated by an Indian individual daily, and a large amount of it is generated from toilets. Ecological Sanitation (EcoSan) is a sustainable system for handling human excreta by using dry composting toilets. EcoSan toilets not only reduce wastewater generation but also generate the natural fertilizer from recycled human excreta, which forms an excellent substitute for chemical fertilizers. This method is based on the principle of recovery and recycling of nutrients from excreta to create a valuable supply for agriculture. 'EcoSan' toilets are being used in several parts of India and Sri Lanka.

Summary

Degrading natural environments, depleting natural resources, pollution, vulnerability to large scale environmental changes and hazards are the core Environmental issues of today. Air pollution by fossil fuel burning and other anthropological activities like industrialization is reaching alarming levels and affecting human health and testing the survival of sensitive species. Domestic and industrial sewage, and agricultural run off are the most common reasons for pollution of water bodies, resulting in reduced dissolved oxygen and increased Biochemical Oxygen demand of water bodies. Eutrophication and algal blooms are regular occurrences today. Industrial wastewaters are often rich in toxic chemicals, heavy metals and organic compounds which harm living organisms and may even result in death of aquatic life. Noise pollution is a threat to human and other animals. It can affect health and disturb peaceful habitats. Agrochemicals and its usages cause many ill effects in human beings, other organisms and soil. Agrochemicals can also cause biomagnification. The solution is to revert to non-chemical farming (use of biofertilisers, biopesticides, protect pollinators) practices. Generation of municipal wastes and their safe disposal are major issues faced by communities today. Solid wastes create environmental problems and must be disposed-off in safe ways. Disposal of solid wastes, radioactive wastes and e-wastes requires further efforts and research. Solid wastes like plastic can be combated by practicing the 4R — refuse, reduce, reuse and recycle. Ecosan toilets are some of the universally accepted eco-friendly practices.

Evaluation

Exercise MCQ — Choose the Correct Answer

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

2. The thickness of Stratospheric Ozone layer is measured in or on:

a) Sieverts units b) Dobson units c) Melson units d) Beaufort Scale

3. 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

4. The use of microorganism metabolism to remove pollutants such as oil spills in the water bodies is known as:

a) Biomagnification b) Bioremediation c) Biomethanation d) Bioreduction

5. Which among the following always decreases in a Food chain across trophic levels?

a) Number b) Accumulated chemicals c) Energy d) Force

6. 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

7. _____ is an ideal disinfectant for waste water.

a) UV Rays b) Chlorination c) Boiling d) Ozonisation

8. SMOG is derived from:

a) Smoke b) Fog c) Both A and B d) Only A

9. Excess of fluoride in drinking water causes:

a) Lung disease b) Intestinal infection c) Fluorosis d) None of the above Exercise 10. Expand the Following

(1) CFC

(2) AQI

(3) PAN

Exercise 11. Short Answer

What is SMOG and how it is harmful for us?

Exercise 12. Activity

List all the wastes that you generate, at home, school or during your trips to other places. Could you very easily reduce the generation of these wastes? Which would be difficult or rather impossible to reduce?

Exercise 13. Write Notes on the Following

a. Eutrophication

b. Algal Bloom

Exercise 14. Short Answer

What effect can fertilizer runoff have on an aquatic ecosystem?

Exercise 15. Short Answer

How can we control air pollution?

Exercise 16. Long Answer

Discuss the role of an individual to reduce environmental pollution.

Exercise 17. Short Answer

How does recycling help reduce pollution?

Exercise 18. Discuss Briefly the Following

a. Catalytic Converter

b. Ecosan Toilets

Exercise 19. Short Answer

What are some solutions to toxic dumping in our oceans?

Exercise 20. Short Answer

Define BOD.

Exercise 21. Short Answer

What is referred to as biomagnification?

Exercise 22. Short Answer

What are the effects of noise pollution?

Glossary

Abiogenesis (n) The emergence of life forms from non-living chemical systems. In contrast with spontaneous generation, abiogenesis is not a process that biologists think continues in a particular environment, such as a planet or moon, once a living system has emerged. Acidogenesis (n) Conversion of simple organic materials into acetate, H₂ and CO₂ by acidogenic bacteria. Algal bloom (n) Presence of large amounts of nutrients in waste water causing excessive growth of planktonic algae. Allergy (n) A hypersensitivity reaction that can involve various deleterious effects. Anthropogenic causes (n) Problems created by human activity. Anthropology (n) The study of differences and similarities, both biological and cultural, in human populations. Anthropology is concerned with typical biological and cultural characteristics of human populations in all periods and in all parts of the world. Antisense DNA (n) It is the noncoding strand complementary to the coding strand in double stranded DNA. The antisense strand serves as a template for mRNA synthesis. Apoptosis (n) Is a form of programmed cell death that occurs in multicellular organisms. Attenuated (adj) Reduced in virulence. Autoradiography (n) It is the use of X-ray or photographic film to detect radioactive materials. Bacteriophages (n) Viruses which infect bacterial cells. Biogeography (n) The scientific study of the geographic distribution of organisms. Canopy (n) The above ground portion of a plant community or crop, formed by the collection of individual plant crowns. Carcinogens (n) Substances causing cancer. Cardiac arrhythmia (n) Any variation from the normal rhythm in the heartbeat. Carrier (n) An individual heterozygous for a recessive gene that is not expressed. Catastrophic (adj) Something or substance that involves or causes a sudden terrible disaster. Chemical Oxygen Demand (n) A measure of the oxygen required to oxidize soluble and particulate organic matter in water. Cirrhosis (n) Scarring of the liver that impairs its functioning. Co-dominance (n) In a heterozygote, the dominant and recessive allele is capable of phenotypic expression. Coacervates (n) Microscopic spontaneously formed spherical aggregates of lipid molecules that are held together by electrostatic forces and that may have been precursor of cells. They are the cluster of molecular aggregates in colloidal form which are bounded by a membrane and grows by absorbing molecules from the environment. Oparin believed that life developed from coacervates. Cytolysis (n) Destruction of cells. Cursorial (adj) A cursorial organism is one that is adapted specifically to run. Cursorial organisms are typically adapted to long-distance running at high speeds; thus, a cheetah is considered cursorial, while a leopard is not. Denaturing (n) Separation or splitting of the double helix into single strands by breaking hydrogen bonds between the two strands. Dendritic cells (n) Professional antigen presenting cells that have long membrane processes. Diapedesis (n) The movement of blood cells (leucocytes) out of the circulatory system and towards the site of tissue damage or infection accompanying inflammation. Dinosaurs (n) A term coined by Sir Richard Owen for giant extinct reptiles. Group of animals that have bird-like and lizard-like facial appearance (Mesozoic). Distribution (n) The occurrence of different organisms in a given area and the way they are distributed in their space, specific time and utilization of their resources. DO (n) Dissolved Oxygen is the amount of gaseous oxygen (O₂) dissolved in the water. Ecotourism (n) Travel undertaken to witness sites or regions of unique natural ecological quality; the provision of services to facilitate such travel. El Nino (n) Unusual warming of surface waters in the eastern tropical Pacific Ocean. Emphysema (n) A serious medical condition that occurs when the lungs become larger and do not work properly, causing difficulty in breathing. Endemism (n) The phenomenon in which the organisms are exclusively restricted to a given area. Endometriosis (n) An abnormal condition in which endometrial tissue that normally lines the uterus grows outside. Eohippus (n) Ancestor of modern horse. Euchromatin (n) A tightly packed form of chromatin that is enriched in genes, and is often under active transcription. Eutrophication (n) Excessive richness of nutrients in a lake or other water bodies frequently due to run off fertilizers from the land causing dense growth of plant life. Fibroids (n) Abnormal growths formed on the outside, inside or in the walls of the uterus. Foetus (n) Developmental stage extending from the ninth week of development to birth. Fossorial (adj) An animal adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, naked mole-rats, clams, and mole salamanders. Galaxy (n) A specific arrangement of stars. Gene bank (n) A facility established for the ex-situ conservation of individuals, seeds, tissues or reproductive cells. Gene pool (n) The total gene content of a whole species. Genetic drift (n) An alteration in the gene frequency. Geology (n) The study of origin and structure of Earth. Glaciers (n) A large mass of ice that moves slowly. Haemophilia (n) A medical condition in which the ability of the blood to clot is severely reduced, causing the patient to bleed severely from even a slight injury. Haemozoin (n) Toxic malarial pigment that causes malaria fever. Hallucination (n) The sensation of seeing, hearing or sensing something that does not exist. Heterochromatin (n) A tightly packed form of DNA or condensed DNA. Homeostasis (n) It is the state of steady internal conditions maintained by living things. Immune reaction (n) The production of antibodies in response to antigens. Interferon (n) An antiviral protein produced from virally infected fibroblasts and leucocytes; induces antiviral state in uninfected cells. Intersex (n) An individual showing a combination of male and female characters. Intra-Uterine Insemination (IUI) (n) Processed sperm sample is infused into the uterus, bypassing the vagina. Intracytoplasmic sperm injection (ICSI) (n) Injection of a sperm directly into the ovum. Intra uterine transfer (IUT) (n) Transfer of embryo with more than 8 celled blastomeres into the uterus. In vitro fertilization (IVF) (n) Fertilization outside the body in the laboratory. In vivo fertilization (n) Fusion of gametes within the female. Inflammation (n) E.g. Vaginitis — inflammation in the vagina; urethritis — inflammation in the urethra; endocervicitis — inflammation inside the cervix; epididymitis — inflammation in the epididymis; prostatitis — inflammation in the prostate gland. Keystone species (n) A species whose loss from an ecosystem would cause a greater than average change in other species population or ecosystem process. Locus (n) The particular point on the chromosome at which the gene for a given trait occurs. Macrophage (n) A large, leucocyte derived from a monocyte that functions in phagocytosis. MALT (n) Mucosal Associated Lymphoid Tissue; collective terms for secondary lymphoid organs located along various mucous membrane surfaces including Peyer's patches, tonsils, appendix. Mast cell (n) A bone marrow derived cell. Menarche (n) Starting of the first menstrual period. Merozoite (n) A trophozoite of Plasmodium found in RBC or liver cells. Methanogenesis (n) Conversion of acetate, H₂ and CO₂ into methane by methane producing bacteria. Molecular biology (n) The branch of biology which attempts to interpret biological events in terms of the physico-chemical properties of molecules in a cell. Molecular Pharming (n) Production of active pharmaceutical substances in genetically modified organisms. Mould (n) An impression of a complete organism or a part of it in the rock that surrounds it. Multiple Sclerosis (n) It is a demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. Mutation (n) Sudden and inheritable changes. Narcotic (n) A powerful drug that produces a relaxed, dreamy state, derived from Opium plant. Nascent RNA (n) Nascent RNA is an immediately formed RNA. In this RNA no post transcriptional modification has occurred. NBOD (n) Nitrogenous BOD. NK cells (n) Natural Killer cells that kill infected and tumor cells. Nondisjunction (n) The failure of homologous chromosomes or sister chromatids to separate properly during cell division. NPK fertilizers (n) Fertilizers with Nitrogen (N), Phosphorus (P) and Potassium (K). Nucleosome (n) A morphologically repeating unit of DNA containing 190 base pairs of DNA folded together with eight histone molecules. Null cell (n) A small population of peripheral blood lymphocytes that lack the membrane markers characteristic of B and T cells. Natural killer cells are included in this group. Ontogeny (n) Life history of an individual. Oocyte (n) The encysted zygote of Plasmodium. Operon (n) A cluster of genes whose expression is controlled by a single operator. Panspermia (n) Units of life in the forms of spores. Permafrost (n) Any ground that remains completely frozen (32°F / 0°C or colder) for at least two years straight. These permanently frozen grounds are most common in regions with high mountains and in Earth's higher latitudes near the North and South Poles. Phenotypic plasticity (n) The ability of one genotype to produce more than one phenotype when exposed to different environments. Phylogeny (n) Record of ancestral history. Planetesimals (n) The fundamental building blocks of the planets as well as the ancestors of asteroids and comets. Polypeptide chain (n) It consists of smaller subunits or amino acids that are linked together. They are the building blocks of proteins. Postpartum (adj) Period of life following childbirth. Precursor (n) A substance from which another is formed, especially by metabolic reaction. Primer (n) A short oligonucleotide that hybridizes the template strand and gives a 3'-OH end for the initiation of nucleic acid synthesis. Probe (n) A single stranded DNA molecule that is 'complementary' to the gene of interest in a sample under study. Pseudopodia (n) Blunt temporary protoplasmic projections found in Amoeba or in some amoeba-like cells. Psychoactive drug (n) A chemical substance that acts on brain and affects the mind and behaviour of user. Puberty (n) Period of reproductive maturity. Pyrolysis (n) Decomposition brought about by high temperatures. Recombinant (n) A cell or organism whose genetic complement results from recombination. Redia (n) Larva in the life cycle of most trematodes. Rheoreceptors (n) Receptors in fish and some amphibians that respond to water currents. Saltation (n) Single step large mutation. Satellite DNA (n) Short highly repeated eukaryotic DNA sequences, usually clustered in heterochromatin and generally not transcribed. Saltatorial (adj) An animal adapted to leaping. They have large, muscular hindlimbs and sometimes, reduced forelimbs. Examples include fleas, froghoppers, grasshoppers, and frogs. Schizogony (n) The process of multiple fission, in which one organism divides to produce many daughter cells. Schizont (n) The trophozoite of Plasmodium grows in size to form the schizont. Selection (n) Choosing the better adapted alleles from the mixed population. Sewage (n) Domestic waste water containing various solid and liquid waste materials including human excreta. Single cell protein (SCP) (n) A protein derived from a culture of single celled organisms used especially as a food supplement. SOD (n) Sediment Oxygen Demand is the rate at which dissolved oxygen is removed from the water column during the decomposition of organic matter in streambed or lakebed sediments. Solubilisation (n) Dissolving the feed stock in water to make a slurry for anaerobic digestion. Speciation (n) Formation of new species from the pre-existing ones. Structural gene (n) A gene coding for the structure of a protein. Taq DNA polymerase (n) A thermostable DNA polymerase obtained from thermophilic bacterium Thermus aquaticus. It helps in the synthesis of DNA. Transgene (n) The target gene responsible for the development of transgenic organism. Trophozoite stage (n) In Plasmodium life cycle, cryptomerozoites in the RBC become round and it modifies into a young trophozoite. Umbilical cord (n) Structure bearing arteries and veins connecting the placenta and the foetus. Variations (n) Dissimilarity between the members of the same species. Vitrification (n) Transformation of a substance into a glass. Volatility (n) A liquid or substance is one that will quickly change into a gas. Withdrawal symptoms (n) The reactions experienced by an addict after he/she stops using drugs. Woolly mammoth (n) A hairy relative of modern elephant that lived in cold climates. Zoogeography (n) Study of details with the geographical distribution of animals. Zygote intra fallopian transfer (ZIFT) (n) Transfer of zygote or embryo with 8 or less than 8 celled blastomeres into the fallopian tube.

MCQs for Higher Studies

Chapter 1 — Reproduction in Organisms

Exercise Higher Order MCQs — Chapter 1

1. "Nothing lives forever, but life continues". What does it mean? [AIPMT 1995]

a) Older dies but new ones are produced by reproduction b) Nothing can produce without death c) Death has nothing to do with the continuation of life d) Parthenogenesis is must for sexual reproduction

2. A few statements describing certain features of reproduction are given below. Select the options that are true for both sexual and asexual reproduction:
1. Gametic fusion takes place   2. Transfer of genetic material takes place   3. Reduction division takes place   4. Progeny have some resemblance with parents

a) 1 and 2 b) 2 and 3 c) 2 and 4 d) 1 and 2

3. A few statements with regard to sexual reproduction are given below. Choose the correct statements:
1. Sexual reproduction does not always require two individuals   2. Sexual reproduction generally involves gametic fusion   3. Meiosis never occurs during sexual reproduction   4. External fertilization is a rule during sexual reproduction

a) 1 and 4 b) 1 and 2 c) 2 and 3 d) 1 and 2

4. Given below are a few statements related to external fertilization. Choose the correct statements:
1. The male and female gametes are formed and released simultaneously   2. Only a few gametes are released into the medium   3. Water is the medium in a majority of organisms exhibiting external fertilization   4. Offspring formed as a result of external fertilization have better chance of survival than those formed inside the organism

a) 3 and 4 b) 1 and 3 c) 2 and 4 d) 1 and 4

5. Which of the following statements support the view that elaborate sexual reproductive process develops much later in the organic evolution?
1) Lower groups of organisms have simpler body design   2) Asexual reproduction is common in lower groups   3) Asexual reproduction is common in higher groups of organisms   4) The high incidence of sexual reproduction is in angiosperms and vertebrates.

a) 1, 2 and 3 b) 1, 3 and 4 c) 1, 2, and 4 d) 2, 3 and 4

Chapter 2 — Human Reproduction

Exercise Higher Order MCQs — Chapter 2

1. Select the incorrect statement. [NEET 2016, phase 1]

a) LH and FSH trigger ovulation in ovary b) LH and FSH decrease gradually during the follicular phase c) LH triggers secretion of androgens from the Leydig cells d) FSH stimulates the sertoli cells which help in spermiogenesis

2. Identify the correct statement on 'inhibitin' [NEET 2016, phase 1]

a) Is produced by granulose cells in ovary and inhibits the secretion of FSH b) Is produced by granulose cells in ovary and inhibits the secretion of LH c) Is produced by nurse cells in testes and inhibits the secretion of LH d) Inhibits the secretion of LH, FSH and prolactin

3. Several hormones like hCG, hPL, oestrogen and progesterone are produced by: (NEET 2016, phase 1)

a) Ovary b) Placenta c) Fallopian tube d) Pituitary

4. Match column 1 with column 2 and select the correct option: [NEET 2016, phase 1]
A. Mons pubis — B. Antrum — C. Trophectoderm — D. Nebenkem
1. Embryo formation — 2. Sperm — 3. Female external genitalia — 4. Graafian follicle

a) 3 4 2 1 b) 3 4 1 2 c) 3 1 4 2 d) 1 4 3 2

5. Which one of the following is not the function of placenta? (NEET, 2013)

a) To facilitate supply of oxygen and nutrients to embryo b) To secrete oestrogen c) To facilitate the removal of carbondioxide and material from embryo d) To secrete oxytocin during parturition

6. The testes in human are situated outside the abdominal cavity inside a pouch called scrotum. The purpose served is for: [AIPMT 2011]

a) Escaping any possible compression by the visceral organs b) Providing more space for the growth of epididymis c) Providing a secondary sexual feature for exhibiting the male sex d) Maintaining the scrotal temperature lower than internal body temperature

7. Hormones secreted by placenta to maintain pregnancy are: [NEET, 2018]

a) hCG, hPL, progesterone, estrogen b) hCG, hPL, estrogen, relaxin, oxytocin c) hCG, hPL, progesterone, prolactin d) hCG, progesterone, estrogen, glucocorticoids

8. Match and select the correct option [NEET, 2018]
a. Proliferative phase — b. Secretory phase — c. Menstruation
1. Breakdown of endometrium lining — 2. Follicular phase — 3. Luteal phase

A) 3 2 1 B) 2 3 1 C) 1 3 2 D) 3 1 2

Chapter 3 — Reproductive Health

Exercise Higher Order MCQs — Chapter 3

1. Which of the following is a hormone releasing Intrauterine Device (IUD)? [AIPMT 2014]

a) Multiload 375 b) LNG-20 c) Cervical cap d) Vault

2. Assisted reproductive technology, IVF involves the transfer of: [AIPMT 2014]

a) Ovum into the fallopian tube b) Zygote into the fallopian tube c) Zygote into the uterus d) Embryo with 16 blastomeres into the fallopian tube

3. In context of amniocentesis, which of the following statements is incorrect? [NEET-I, 2016]

a) It is usually done when a woman is between 14-16 weeks pregnant b) It is used for prenatal sex determination c) It can be used for detection of Down syndrome d) It can be used for detection of Cleft palate

4. Which of the following approach does not give the defined action of contraceptive? [NEET-I, 2016]

a) Barrier methods — Prevent fertilization b) Intra uterine devices — Increases phagocytosis of sperms, suppresses sperm motility and fertilizing capacity of sperms c) Hormonal contraceptives — Prevent retard entry of sperms, prevent ovulation and fertilization d) Vasectomy — Prevents spermatogenesis

Chapter 4 — Principle of Inheritance and Variation

Exercise Higher Order MCQs — Chapter 4

1. The fruit fly Drosophila melanogaster was found to be very suitable for experimental verification of chromosomal theory of inheritance by Morgan and his colleagues because: [AIPMT MAINS 2010]

a) It reproduces parthenogenetically b) A single mating produces two young flies c) Smaller female is easily recognizable from large male d) It completes the life cycle in about two weeks

2. Which one of the following cannot be explained on the basis of Mendel's Law of Dominance? [AIPMT PRE 2010]

a) The discrete unit controlling a particular character is called a factor b) Out of one pair factor one is dominant and the other recessive c) Alleles do not show any blending and both the characters recover as such in F2 generation d) Factors occur in pairs

3. ABO blood groups in humans are controlled by the gene I. It has three alleles – I^A, I^B and i. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur? [AIPMT PRE 2010]

a) Three b) One c) Four d) Two

4. Which one of the following symbols and its representation, used in human pedigree analysis is correct? [AIPMT PRE 2010]

a) □=○ = Mating between relatives b) ○ = Unaffected male c) □ = Unaffected female d) ◊ = Male affected

5. Which one of the following conditions correctly describes the manner of determining the sex in the given example? [AIPMT PRE 2011]

a) XO type of sex chromosomes determine male sex in grasshopper b) XO condition in humans as found in Turner syndrome, determines female sex c) Homozygous sex chromosomes (XX) produce male in Drosophila d) Homozygous sex chromosomes (ZZ) determine female sex in birds

6. A normal-visioned man whose father was blind, marries a woman whose father was also colour blind. They have their first child as a daughter. What are the chances that this child would be colour blind? [AIPMT PRE 2012]

a) 100% b) 0% c) 25% d) 50%

7. Which of the following statements is not true of two genes that show 50 per cent recombination frequency? [AIPMT 2013]

a) The genes may be on different chromosomes b) The genes are tightly linked c) The genes show independent assortment d) If the genes are present on the same chromosome

8. A pleiotropic gene: [RE-AIPMT 2015]

a) Is a gene evolved during Pliocene b) Controls a trait only in combination with another gene c) Controls multiple traits in an individual d) Is expressed only in primitive plants

9. A gene showing codominance has: [RE-AIPMT 2015]

a) Alleles tightly linked on the same chromosome b) Alleles that are recessive to each other c) Both alleles independently expressed in the heterozygote d) One allele dominant on the other

10. Pick out the correct statements: [NEET-I, 2016]
A. Haemophilia is a sex-linked recessive disease   B. Down's syndrome is due to aneuploidy   C. Phenylketonuria is an autosomal recessive gene disorder   D. Sickle cell anaemia is an X-linked recessive

Book-back Exercises — Questions & Answers

Answers generated strictly from the Samacheer Kalvi textbook content. Attempt each question first, then click "Show Answer" to check.

I. Choose the Correct Answer

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

Explanation: According to the chapter, Right to clean water is a fundamental right under the Indian Constitution (Article 21).

2. The thickness of Stratospheric Ozone layer is measured in or on:

a) Sieverts units b) Dobson units c) Melson units d) Beaufort Scale

Answer: b) Dobson units

Explanation: The thickness of the stratospheric ozone layer is measured in Dobson units as given in the chapter evaluation section.

3. 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

Explanation: As per the chapter evaluation, China is the highest per capita emitter of Carbon dioxide in the world as per 2017 statistics.

4. The use of microorganism metabolism to remove pollutants such as oil spills in the water bodies is known as

a) Biomagnification b) Bioremediation c) Biomethanation d) Bioreduction

Answer: b) Bioremediation

Explanation: Bioremediation refers to the use of microorganism metabolism to remove pollutants such as oil spills in water bodies, as stated in the chapter evaluation.

5. 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

Explanation: Energy always decreases across trophic levels in a food chain, as indicated in the chapter evaluation section.

6. 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

Explanation: Copper is the most abundant metal found in e-waste generated by mobile phones, as given in the chapter evaluation section.

7. ______ is/are an ideal disinfectant for waste water.

a) UV Rays b) Chlorination c) Boiling d) Ozonisation

Answer: a) UV Rays

Explanation: According to the chapter, UV is an ideal disinfectant for wastewater since it does not alter the water quality except for inactivating microorganisms. It is a chemical-free process that can completely replace the existing chlorination system.

8. SMOG is derived from:

a) Smoke b) Fog c) Both A and B d) Only A

Answer: c) Both A and B

Explanation: The chapter states that the word SMOG comes from a mixture of the words smoke and fog.

9. Excess of fluoride in drinking water causes:

a) Lung disease b) Intestinal infection c) Fluorosis d) None of the above

Answer: c) Fluorosis

Explanation: The chapter clearly states that excess of fluoride in drinking water causes fluorosis.

II. Answer Briefly

10. Expand (1) CFC (2) AQI (3) PAN

Answer:

1. CFC – Chlorofluorocarbons

2. AQI – Air Quality Index

3. PAN – Peroxyacetyl Nitrate

11. What is SMOG and how it is harmful for us?

Answer: Smog is a type of air pollution caused by tiny particles in the air. The word comes from a mixture of the words smoke and fog. Photochemical smog is created when sunlight reacts with nitrogen oxides and volatile organic compounds found in fossil fuel emissions from automobiles, factories, and power plants. Smog can make breathing more difficult, especially for people with asthma. It also damages crops, causes health problems in pets, farm animals and human beings, and causes corrosive damage to buildings and vehicles. Peroxyacetyl nitrate (PAN), a secondary pollutant in photochemical smog, causes eye irritation.

12. List all the wastes that you generate, at home, school or during your trips to other places. Could you very easily reduce the generation of these wastes? Which would be difficult or rather impossible to reduce?

Answer: Wastes generated include food wastes, plastics, paper, glass, metals, yard wastes from homes; packaging wastes, chemicals, metal parts from industries; and thin/thick plastics, food wastes, paper from commercial sources. According to the chapter, easily reducible wastes include organic/food wastes (through composting) and paper. Difficult or near-impossible to reduce wastes include radioactive waste, e-waste, and non-degradable plastics. The chapter recommends the '4R' mantra — Refuse, Reduce, Reuse and Recycle — as the best available remedy especially for plastic waste.

13. Write notes on the following: a. Eutrophication b. Algal Bloom

Answer:

a. Eutrophication: When run-off from land containing nutrients reaches water bodies like lakes, it results in dense growth of plant life. This phenomenon is called Eutrophication. Natural aging of lakes also leads to nutrient enrichment. Pollutants from anthropogenic activities like effluents from industries and homes can radically accelerate this aging process, known as Cultural or Accelerated Eutrophication. Nutrients stimulate the growth of algae and water hyacinth, cause clogging of canals and rivers, produce unsightly foam, unpleasant odours, and deprive the water of dissolved oxygen.

b. Algal Bloom: Algal bloom refers to the presence of large amounts of nutrients in waste water causing excessive growth of planktonic algae. It affects the quality of water bodies. Red tides, if they occur, can be lethal to aquatic organisms. Algal blooms are a direct consequence of eutrophication and nutrient enrichment of water bodies.

14. What effect can fertilizer runoff have on an aquatic ecosystem?

Answer: Fertilizer runoff from agricultural fields introduces excess nutrients (nitrates and phosphates) into water bodies, causing eutrophication. This stimulates the growth of algae and water hyacinth, leading to algal blooms. Algal blooms reduce dissolved oxygen in the water, cause clogging of canals and rivers, displace native plants, and produce unpleasant odours. This can be lethal to aquatic organisms. Red tides, which can occur during algal blooms, are particularly harmful to aquatic life. Overall, fertilizer runoff disrupts the natural food chains and aquatic ecosystems.

15. How can we control air pollution?

Answer: Air pollution can be controlled by the following measures as mentioned in the chapter: Trees are the best remedy for urban particulate and gaseous pollution; forests act as carbon sinks and lungs of the planet; catalytic converters in vehicles help reduce polluting gases drastically; diesel exhaust filters cut particulates; electrostatic precipitators reduce release of industrial pollutants; indoor plants and high-performance biofilters improve indoor air quality. Legal measures include the Air (Prevention and Control of Pollution) Act 1981 (amended 1987), Bharat Stage VI norms from 2020, road traffic rationing, promoting public transport, increasing green cover, reducing carbon emissions, encouraging renewable energy, and making Environmental Impact Assessment mandatory.

16. Discuss the role of an individual to reduce environmental pollution.

Answer: An individual can play a vital role in reducing environmental pollution through the following practices mentioned in the chapter: practicing carpooling and using public transport to reduce air pollution; planting trees to absorb noise and air pollutants; following the '4R' mantra — Refuse, Reduce, Reuse and Recycle — especially for plastic waste; segregating waste at source; using eco-friendly products; avoiding firecrackers; not littering water bodies; participating in public awareness campaigns like Swachh Bharat Abhiyan. Every individual should be environmentally aware and take responsibility for protecting the environment, as stated in the chapter introduction.

17. How does recycling help reduce pollution?

Answer: Recycling is one of the key components of the '4R' mantra (Refuse, Reduce, Reuse and Recycle) recommended in the chapter as the best remedy for waste pollution. Recycling helps reduce pollution by decreasing the volume of solid waste that goes to landfill sites, which produce foul smells and toxic gases like dioxins when hazardous materials are burned. Recycling e-waste prevents the leaching of heavy metals like lead, mercury, and cadmium into the environment. It also reduces the need for new raw materials, thereby lowering industrial emissions and air pollution. Proper recycling of radioactive and medical waste prevents contamination of soil and water bodies.

18. Discuss briefly the following: a. Catalytic converter b. Ecosan toilets

Answer:

a. Catalytic Converter: Catalytic converters are devices fitted in vehicles that help to reduce polluting gases drastically. They are listed as one of the important control measures for air pollution in the chapter. Diesel exhaust filters in automobiles also cut particulates, together with catalytic converters helping to significantly improve air quality.

b. Ecosan Toilets: Ecological Sanitation (EcoSan) is a sustainable system for handling human excreta by using dry composting toilets. EcoSan toilets not only reduce wastewater generation but also generate natural fertilizer from recycled human excreta, which forms an excellent substitute for chemical fertilizers. This method is based on the principle of recovery and recycling of nutrients from excreta to create a valuable supply for agriculture. EcoSan toilets are being used in several parts of India and Sri Lanka.

19. What are some solutions to toxic dumping in our oceans?

Answer: Based on the chapter, the following solutions can be adopted to address toxic dumping in oceans: Setting up Effluent Treatment Plants (ETP) and Sewage Treatment Plants (STP) to treat industrial and domestic waste before discharge; regulating and controlling pollutant discharge at the point of generation; preventing oil spills from tankers through better maritime safety regulations; restricting the use of non-degradable plastics and practicing the '4R' mantra (Refuse, Reduce, Reuse, Recycle); implementing stricter environmental laws and making Environmental Impact Assessment mandatory; promoting public awareness and peoples' involvement in ocean conservation. The National river conservation plan (NRCP) and the Ministry of Environment, Forest and Climate Change (MoEFCC) play important roles in policy implementation.

20. Define BOD.

Answer: BOD stands for Biochemical Oxygen Demand (or Biological Oxygen Demand). It refers to the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidized by bacteria. The greater the BOD of waste water, the more is its polluting potential. Sewage water is treated until the BOD is reduced significantly.

21. What is referred to as biomagnification?

Answer: When non-degradable substances enter the food chain, they do not get metabolized, broken down, or expelled. Instead, they get transferred up the trophic levels of the food chain. During this process, they show an increase in concentration at successive trophic levels, which is referred to as biomagnification. This results in increased toxicity and may even be lethal. This phenomenon is well established for mercury and DDT. For example, in an aquatic food chain, the concentration of DDT is enhanced at successive trophic levels, making it most concentrated in organisms at the top of the food chain.

22. What are the effects of noise pollution?

Answer: According to the chapter, the effects of noise pollution include: heart disease, high blood pressure, stress-related illness, sleep disruption, hearing loss (deafness), and productivity loss (as stated by USEPA). It also causes increased stress and tension, nervousness, irritability, anxiety, depression and panic attacks. Other effects include peptic ulcer, severe headache, and memory loss. Marine animals are affected by noise pollution from offshore and port activities. Fire crackers frighten animals, and birds are often affected by increased air traffic. The World Health Organization has proposed that noise must be recognized as a major threat to human well-being.

📝 Summary

1. Pollution is any undesirable change in the physical, chemical, and biological characteristics of the environment due to natural causes and human activities, and pollutants are classified as rapidly degradable, slowly degradable, and non-degradable based on how they break down in the environment.
2. Earth faces numerous environmental concerns including air pollution, water pollution, noise pollution, global warming, acid rain, biomagnification, eutrophication, deforestation, and ozone layer depletion, all of which have accelerated due to human exploitation of natural resources.
3. Air pollution results from alterations in the composition of the earth's atmosphere by natural or anthropogenic (human) activities, with major threats including depletion of the ozone layer by CFCs used as refrigerants and global warming caused by elevated CO2 from industries, deforestation, and partial combustion.
4. Non-degradable pollutants such as toxic elements like lead, mercury, cadmium, chromium, and nickel cannot be broken down by natural processes and tend to accumulate in the environment through a process called biomagnification, making them especially dangerous to ecosystems and human health.
5. A clean environment is essential for a peaceful and healthy life, and every individual must be environmentally aware and participate in eco-friendly practices — such as organic farming, solid waste management, and ecosan toilets — to help mitigate pollution and protect the planet.