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AHE-01: Human Environment

AHE-01: Human Environment

IGNOU Solved Assignment Solution for 2020-21

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Assignment Code: AHE-01/TMA/ 2021

Course Code: AHE-01

Assignment Name; Human Environment

Year: 2020-2021

Verification Status: Verified by Professor

Valid Until: December 31, 2021


Q1) Write short notes on the following:

i) Competition

ii) Niche

iii) Predation

iv) Freshwater ecosystem


Ans) i) Competition:

Competition occurs in nature generally, but not necessarily, when resources like food, space, mates are limited. Resource limitation leading to competition is implicit in Darwin's ideas on struggle for existence and survival of the fittest. Though not widely recognised competition could occur even when resources are not limiting. For example, consider species A that does not require a certain resource for its existence, but it prevents species B from acquiring that resource which the latter needs. The consequence is that the growth and reproduction of species B are reduced because of the presence of species A in the same habitat. This is called ' interference competition' and appears to be rather common among the higher animal groups. Although competition is most intense when the competing species are closely related, because their requirements are similar, competition between taxonomically unrelated species is not uncommon.


Ans) ii) Niche

A species niche is its unique functional role or place in an ecosystem. It is a description of all the biological, physical, and chemical factors that a species needs to Survive, stay healthy and reproduce. To describe a species ecological niche, one must know where it lives-habitat niche; the species it eats or decomposes, what species it competes with-its food niche; how and when it reproduces-its reproductive niche and its temperature shade, slope humidity and other  equirements i.e., its physical and chemical niche. A niche is something unique for a species, which means no two species have identical niches. We can readily accept the fact that the niches of two species of Crab – one living in soft mud and the other in sandy burrows, are quite different, but it is not easy to understand how the niches of two crab species, both living in similar sand burrows could be different. Ecologists consider niche as a species-specific attribute, defined not just by its habitat but by all the parameters that are of relevance to the organism.



Ans) iii) Predation

This is an interaction in which one organism, predator kills another, prey for food. this is a process of paramount importance not only in natural ecosystems but to man also, because he is either directly a predator himself (as when he captures fish from the sea, hunts game animals in a forest), or has to deal with natural predators which are directly harmful to him or kill prey that are beneficial to him.


Following are its important roles:

  1. Predation helps to channelise through different trophic levels the energy fixed by photosynthetic plants. But for predation, the 'grass-deer-tiger' food chain would not obviously exist! Remember, the grass 'considers' deer as its predator; in this sense, to a plant the sparrow that eats its seeds is also a predator.

  2.  Predators can bring down the intensity of interspecific competition in a community by selectively preying on the competitively superior species and keep their densities low. This permits the weaker species to persist in the habitat.


Ans) iv) Freshwater ecosystem

Fresh water ecosystems are characterised as lotic (having flowing water) or lentic (still water). Lotic water systems which include freshwater streams, springs, rivulets, creaks, brooks and rivers etc., tend to become over their course from being narrow, shallow and ' relatively rapid to increasingly broad, deep and slow moving. Waterfalls are not uncommon features of lotic ecosystems. As would be expected only organisms well adapted to - maintaining their position in flowing water and capable of adhering to an exposed surface are found in the upper reaches of a stream. Adhering organisms associated with large aquatic plants are termed periphyton.


Q2) How deforestation and desertification can disturb the stability of climate of an area? (10)

Ans) Desertification, melting of the Arctic ice caps, and thawing of the Siberian permafrost are some examples of the positive feedback loop. For instance, global warming is speeding up desertification by increasing the frequency and intensity of droughts, floods, and forest fires. Desertification, in turn, is releasing large quantities of soil carbon into the atmosphere, further exacerbating warming. Similarly, global warming has started to thaw the Siberian permafrost. This could potentially release billions of tonnes of CO2 into the atmosphere, warming the earth further and causing more permafrost to thaw. These are nightmarish scenarios, but they may slowly be becoming a reality. The fires raging in Brazil’s Amazon rainforest are a vivid manifestation of this.


Land degradation and deforestation are responsible for more than 20% of the global greenhouse gas (GHG) emissions. The Intergovernmental Panel on Climate Change’s Special Report on Global Warming of 1.5°C clearly states that we will not only have to stop these emissions but also deploy large-scale ‘carbon removal’ from the atmosphere to meet the target of keeping the global temperature increase within 1.5°C. The best way to remove carbon is by sequestering it in its natural sinks—forests, grasslands, and soil. This also has the added benefit of halting desertification and land degradation, which is threatening the world’s food and water security.


According to a recent report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), “land degradation is almost always the result of multiple interacting causes”.


The direct causes of desertification can be broadly divided between those relating to how the land is – or is not – managed and those relating to the climate. The former includes factors such as deforestation, overgrazing of livestock, over-cultivation of crops and inappropriate irrigation; the latter includes natural fluctuations in climate and global warming because of human-caused greenhouse gas emissions.


Then there are underlying causes as well, the IPBES report notes, including “economic, demographic, technological, institutional and cultural drivers”.


Q3) Define carrying capacity. Explain different types of carrying capacity. How carrying capacity is different from biotic potential? (10)

Ans) The concept of carrying capacity or the ultimate limit of tolerance has been in use for some

time in engineering designs, particularly those relating to material subject to loads. Every material has a limit of load that it can bear, which if exceeded, it fails or breaks. To ensure a cushion, a safe limit, lower than the maximum load, is taken as the ultimate one or tolerance or bearing capacity. In respect of productive potential of land, this concept has been used to indicate the number of cattle or cattle equivalent of other livestock that it can sustain throughout the year on one hectare of range or pasture land. The simplistic diagram on logarithmic scale for periods of one year to one million yearn More 2000 AD attempts to construct the growth of world population that lived on earth from the period when man used technique of hunting-gathering, to farm mechanistic and then to application of fertilisers. It is apparent from the figure that population increased with advancement in the technique for obtaining food, i.e., population has increased with the increase in food production. In other words, the spurts in the curve compound to innovations, which result in an increase in the carrying capacity of the system.


Human population has shown manifold increase which necessitated an ever-increasing demand on resources. Consequent over-consumption of resources was often satisfied by consuming the productive resources, the base itself, a biological equivalent of deficit financing. The associated interventions, have been disruptive and destructive to the environment, as evident by widespread shortage of fuelwood and water, decline in land productivity, erosion in the diversity of flora and fauna etc. The assimilative capacity can absorb wastes, to some extent but cannot regenerate the land productivity or replenish the water regimes or restore the lost genetic diversity. There is a pressing need for some positive counter-interventions like afforestation, land reclamation, preservation of wildlife etc.

Carrying capacity, like most other environmental attributes, is subject to change. This could be in consequence to natural evolutionary forces transforming both physical resources and composition of life forms. This could also be a result of changes in the human society due to either introduction of new technology, institutional innovations, government policy or factors such as minimum per capita income and material requirements. Further, the changes in carrying capacity could be both positive as well as fugitive. Thus, there is a need to develop objectives for preparing an alternate plan for sustainable development. Production inputs like fertilisers, pest control. power, high yielding cultivars and resource conservation measures increase the carrying capacity for some time.


Q4.i) What is hazardous waste? Describe its characteristics and differentiate between toxic and hazardous wastes.

Ans) i) Living beings require food. They use food for their growth and development and for producing energy. In this process they also generate wastes.



Hazardous wastes are chemical by-products of an industry, a factory, or a chemical plant. They may result from household activities or even from a hospital or a research laboratory. Armed conflicts, where nuclear or chemical weapons are used, also release enormous amounts of hazardous wastes. A chemical produced by any 01 the above sources which may endanger human health, pollute the environment, or carry hidden risk to life if managed or disposed off improperly is called 'hazardous'.


Toxic Versus Hazardous

Generally, the terms "toxic" and "hazardous" are used interchangeably as if they were synonymous. But this is not true. The former refers to intrinsic characteristics whereas the latter includes extrinsic characteristics also. "Toxic"-defines the capacity of a substance to produce injury after entering the metabolic processes of the consumer, an animal, a plant, or a human being. The changes caused may either be pathogenic, mutagenic, teratogenic, or carcinogenic.


The term 'hazardous' denotes the. potential of a substance to pose threat to life or material through any one of properties mentioned above, namely, toxicity, ignitibility, corrosiveness, reactivity, explosiveness, or radioactivity. The term "hazardous is thus broader and includes "toxic" wastes in its spectrum. You can see that some substances may be hazardous on more than one account. For example, benzene is toxic as well as ignitable; strong acids and alkalis from corrosive mixtures which sometimes explode if improperly handled.


Definition of Hazardous Waste

Hazardous waste means a waste, which because of its quantity, concentration or physical, chemical or biological characteristics may : a) 'muse or significantly contribute to an increase in mortality or an increase in serious, irreversible or incapacitating reversible illness, or I b) pose a substantial present or potential hazard to human health or tb environment when improperly treated, stored, transported, or disposed of, or otherwise managed.


Q4) ii) Describe briefly the disposal of hazardous wastes in India.

Ans) We would now briefly discuss generation and disposal of hazardous waste in India.

1. Sources of 'Waste Generation

In general, hazardous waste generation can be broadly grouped into two categories, viz., Process-oriented and Pollution Control-oriented. The process-oriented waste is generated during the processing of raw materials to get the finished. products, while pollution control-oriented waste originates from the treatment of gaseous and liquid effluents.


The magnitude and characteristics of industrial hazardous waste is dependent on various factors-for example, size of the unit, production technologies, process efficiency and raw materials processed. In India, there are industries generating large quantities of solid waste with relatively less concentration of hazardous constituents, (e.g., metallurgical industry like iron and steel, fertilisers, thermal -power stations, etc.).


Prevalent Methods of Disposal

In the absence of proper regulatory control over handling, treatment and disposal, the hazardous wastes are mostly disposed wherever the space is easily available and accessible to the waste generators. Presently, the following methods of disposal of hazardous industrial wastes are followed in our country:


Disposal along with city refuse

Disposal on riverbeds and banks

Open pit burning

Disposal in low lying areas, estuaries, and seas

Burning in self designed incinerators. % ,


Most of the heavy metal bearing and highly toxic wastes containing as pesticides, solvent distillates, phenolics, cyanide waste, etc. are being disposed off using above mentioned methods. From the standpoint of impact what is significant is the method of disposal and the compatibility and complex interaction of these wastes with th~: receiving environment, a proper evaluation of which is not available in India. Let us see what the harmful effects of disposal of wastes in an improper way are.




Q 5. Describe the epidemiological approach used to study health problems related to the environment. (10)

Ans) epidemiological approach is an important way of studying the influence of environmental contaminants on human beings. It encompasses two main areas :


  1. Descriptive Epidemiology: in which a study of the distribution of disease or health hazards in the human population is conducted.

  2. Analytic Epidemiology: in which a study of the determinants or underlying causes or risk factors of disease is undertaken.


The main objective of epidemiology is to understand or discover the cause of diseases and suggest best means of prevention of diseases or controlling their spread and provide guidance to Health Services. In the epidemiological approach, the following five basic questions must be answered,

  1. When does the disease occur? (Time)

  2. Where does the disease occur? (Place)

  3. Who are the people affected? (Persons involved)

  4. Why has it happened? (Causes)

  5. What should be done to prevent or control the disease? (Prevention, control, and eradication)


Such approach helps in identifying the environmental causative of the disease and suggest the ways of its prevention. For example, in epidemiological study of respiratory disorders in an area, it was found that disease has been prevalent for some years, the affected people work in textile industry and show common 'symptoms of disease. Among the workers only those are affected who breathe in fibres. So fibres are linked with disease. After verification of such data, physical and medical means of control and prevention of disease can be planned. Environmental factors are considered in the light of area of incidence and time of exposure. For example, a single event such as an accident in a chemical plant requires immediate inset.



Q6. Discuss three conceptual models highlighting the symptoms and causes in order to understand the environmental problems. (10)

Ans) three conceptual models to understand the environmental problems are:


Population, Resource and Pollution Model

Population, Resource and Pollution Model (PRP model) show that all organisms and human populations from all the societies; hunting and gathering, agricultural and - Development and Environment modern societies, a cadre and use the resources from the environment for them

survival and development. The acquisition and use of resources often lead to pollution of air, water, and soil, threating life by affecting a variety of environmental ampents. For example, water pollution may kill fish, mining and building of dams destroy the land ruining the habitat of many animals. To minimise pollution and help other organisms to share the planet, it is necessary to adopt a scientific approach in acquisition and use of natural resources.

Multiple Cause and Effect Model

Multiple cause and effect model is aimed at understanding the current entail problems at individual level and show that these problems are caused by various factors like population, per capita consumption, economics, technology, junk policies, politics, biology, psychology and culture


The human population destroys wildlife habitat and pollutes the environment in many ways in order to satisfy its ever-growing need for food, clothing and shelter. The developmental process such as building of roads, and houses by cutting forests and polluting the water and air with factory effluents also adds to the ever-growing problems. The larger the human population the greater is the environmental damage caused.


Impact Analysis Model

Impact Analysis Model shows the impact of human activities on both, abiotic environmental factors, i.e. air, water and land; and biotic factors, i.e. plants, animals and other organisms on this planet. The impact of human activities on our environment and biota is summarised in Fig. 19.6. Biota are affected directly by the human activities as well as indirectly through the environmental degradation caused by human activities. We will discuss the impact analysis model by taking the example of mining and use of coal as fuel.


Impact on Environment includes air, water and land pollution. Mining or related activities such as heavy vehicles commuting on dirty roads near mines may cause air pollution. Air pollution due to the combustion of coal in a thermal power-station is of greater intensity. A single 1000-megawatt coal-fuelled power plant which serves roughly one million people, emits approximately 1,500 to 30,000 metric tons of particulates, as smoke and ashes and 11,000 to 110,000 metric tons of sulphur dioxide gas every year.


Q7. Discuss the problems in preparing a reliable database report on environment. (10)

Ans) The developed and industrialised countries have been facing tremendous environmental problems on account of their unplanned industrialisation and growth in developmental activities. Consequently, they started turning their attention to environmental management much earlier: They also had enough resources to support these activities. The developing countries which on the other hand, had just started industrialisation and developmental activities, did not face such problem so acutely. The environmental problems of the developing countries were generally related to ' underdevelopment, poverty and lack of resources. For them, demands such as drinking water, food, shelter, clothing, and health were much more important, and for this reason they could not pay proper attention towards environmental management. Also, the subject of environment being new, very little was known about its relationship to other sciences such as climatology, sociology, geography, economics, health and hygiene. Only recently, people have started realising that management of the environment is not possible unless we have information on other areas related to environment.


Database is the collection of interrelated data. Whenever required. the data or a part of it can be retrieved. Database is generally, based on computerised information. However, information or data stored in any other form also forms database, for example, the cards used in a library to locate a book. The cards contain requisite information about all the books, journals, magazines, etc., available in the library. Similarly, compiling information about the individuals in a city, state or a country is also generating a database. It is difficult to use the information available in the form of cards, reports, books, files, etc., if the information is large. The same information, if fed into a computer in a proper way may become easily manageable and we can retrieve the desired information very fast. This is why the term database is generally used in relation to computerised information.



Q8) i) Explain means of recycling and reuse of solid wastes produced by cities and industries.

Ans) Recognising that our resources are finite and continued pollution will be difficult to rectify in coming times, the management of solid wastes has become5mportant. Before disposal, a waste should be considered for the following possibilities: ' Reduction in raw materials and solid waste quantities Reuse of waste materials recovery.


Energy recovery

I) Reduction in Raw Materials and Solid Waste

Solid wastes are generated at the start of the process beginning with the mining of raw material. Thereafter, solid wastes are generated at every step in the process of conversion of goods into products. The products are then used by the consumer whence again wastes are generated. Clearly if a reduction in the usage of raw materials is to occur the quantity of waste must be curtailed.


Reuse of waste materials now occurs most commonly in those situations where a product has utility in more than one applications. For example, the paper bags used to bring home groceries are used to store household wastes prior to placing them in containers used for storage for collection. Soup and vegetable containers are used to store cooking medium, like ghee or oil. Newspapers are used to start fires in fireplaces; they are also tightly rolled and used as logs for burning. While all the above reuses are important, their impact on generation of solid wastes is minimal. A much*larger impact wovld occur if this habit is encouraged on a large-scale, in urban and town communities.

Material Recovery and Recycling

Several materials present in municipal and industrial wastes are suitable for recovery and recycling about 10-15 per cent of solid waste are recoverable.


IV) Energy Recovery

After segregation of wastes in the above-mentioned categories, the remainder is considered for the recovery of heat by burning (incineration). Because about 70 per I cent of the components that comprise solid waste are organic, the potential for recovery of heat energy is high.


Q8) ii) Describe various means of conserving energy.

Ans) Energy generation and environmental conservation are the twin issues arising from exploitative interaction of man with natural resources. A 1987 report of the International Energy Agency contains a simple but remarkable statement:


"Investment in energy conservation at the margin provides a better return than investment in energy supply." Now, what do we mean by this? This means that conservation of a unit of energy is cheaper and environmentally more desirable than to generate an additional unit. For, it is estimated that generation of every additional kilowatt hour of energy requires an investment of Rs. 7,000 to 12,000 in the form of new energy generation equipment’s.


Excessive utilisation of coal and oil for generation of electricity leads to the multiple problems of acid rain, and rising carbon dioxide levels in the atmosphere. There are also political and economic implications like the increasing tension in the Persian Gulf which is the major petroleum exporting area, and falling international competitiveness. All these threaten to strangle the world economy in a stagnation. Let us see how some steps taken to resolve these complex problems have tangled the issues further.


To reduce dependence on oil for generation of electricity by burning coal and oil, hydroelectric power stations and atomic energy stations were advocated. Huge dams can make substantial contributions to economic development in electricity-short developing countries like India, but as in any large-scale electricity generating option, there are trade-offs. Reservoirs inundate forests, farmland and wildlife habitats and uproot entire communities of indigenous people. A million people will be forced from their homes in Central India if a project to build all the small and big dams in the Nannada Valley is pursued; The setting up of hydroelectric power stations, also known as hydel plants, upsets the isostatic balance of the area, submerges the surrounding animal - and planj - populations, renders the local inhabitants jobless and homeless. Thus, hasty solutions to a given problem may create more complications rather than solving it.


Q9. Explain economic implications of waste generation and waste disposal. (10)

Ans) Everything indeed, we use and consume-the food we eat, the clothes we wear, the house we live in, the course book you are now reading-are all essentially made of materials and energy drawn from environment-the earth's crust and surface, atmosphere or water. We never get something from nothing. W when the materials extracted from environment are not in the desired usable forms, they are subjected to knowledge-based processing called 'technology'. By applying energy, they are converted into useful products and services. It holds good for every activity we perform, whether, it has to do with industry, agriculture, transport services, or domestic sector both urban and rural areas.


 It must be recognised here that in any technological process, all the material inputs or input resources are NOT and perhaps can NEVER be transformed into desirable products and services completely. Same amount of waste is always produced. How much of the given inputs shall finally appear as products and services at the end of processing-run-through, or how much shall go out as wastes, would depend on what is produced, the technological processes employed and how efficiently these processes are managed. One thing, however, is certain that wastes would be generated-come what may. It is inevitable.


Wastes are also generated when people take in food, water, air or use material to make industrial products. When waste is produced, in 'excess, it pollutes the environment. However, some of the wastes can be recycled. As the 'needs' and 'wants' of people increase, per capita extraction of materials from environment also. Increases progressively. For instance, per capita material extraction in USA during early 80s was as high as 60 kgs. per day. With increase in population the world production of goods and services has also been growing rapidly.


Excessive wastes. when generated, indicate inefficiency. They represent economic loss, and therefore associate with it is a hidden cost. Under obligations and mandates of environment protection or pollution control laws, when wastes have to be arrested, treated, stored, transported and disposed off in environmentally acceptable manner, additional cost is incurred.



Q10. “Social awareness is necessary for environmental management” Explain this statement giving examples from agriculture, industry and health. (10)

Ans) There is a need to develop a strategy for the management of environment.


Concerning the Agricultural Productivity

No one questions the role of forests in maintaining the environment, but at the same time no one has ever questioned the need for agriculture. Agriculture was the first activity in the evolutionary process of present civilisation. 'The concern about environment has come up here because of the rapidly changing balance between the forested and cultivated land.


  1. Land Use Pattern                                                             

  2. Water Resources

  3. Irrigation Patterns

  4. Issue of Social Awareness



Concerning Industry

Green revolution in a way is the result of industrial development. Demand for more food resulted in the application of science and technology for higher production. Related industries like fertilisers, chemicals, foundries, etc. came into existence. though the technical process rests on the concentration of capital and technology in the hands of a fewer people. But its external effects are carried far afield. This development has resulted in consumption of valuable natural resources at a faster rate on the one hand, and the production of pollutants on the other. The consequences are:


1) Increased waste production and pollution

As industrialisation increases, the use of polluting materials grows at a fast rate. The developing countries suffer from the problems of ill-management of polluting products. The developed countries suffer from the affluence causing the pollution.


2) Cost of Pollution

Not only is pollution a problem in terms of public health, it also creates problems in terms of the expenditure on pollution abatement and loss of quality and quantity of resources. It is a common experience that the green belts around industrial areas are becoming a luxury.


Concerning Health

I If one takes the above argument further, the health concerns have been created because of industrial development on one hand and the ecological imbalances caused by the need for higher agriculture productivity on the other.


1) Urbanisation

The worldwide tendency of people to crowd together has resulted in higher population densities in many cities. People have migrated from rural areas in search of alternative sources of livelihood.


2) High Incidence of Diseases

Poor environmental sanitation and inadequate supply of safe drinking water is a major factor leading to diseases in the cities, especially in slum areas. The capital city of Delhi has faced this problem in the recent past and newspapers are full of such news from other parts of the country.


3) Malnutrition

As mentioned earlier, unhealthy living conditions and uncertain source of income have caused problems of malnutrition in the urban sectors, contributing to health problems. This is further aggravated when developing countries do not have a national system of health.

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