BEVAE-181 Solved Assignment

Question 1. Ecological importance of forests in today’s world

Why forests are more critical now than ever

Today we hear about heat waves, irregular monsoon, flash floods, landslides and poor air quality. In almost every one of these problems, forests silently play a protective role. That is why their ecological importance feels much bigger now than it did a few decades ago.

• Climate regulation and carbon storage: Trees absorb carbon dioxide and lock it in their trunks, branches, roots and soil. When a city expands into a nearby forest area, you can literally feel the change: hotter summers, less pleasant evenings and more “heat island” effect because there are fewer trees to provide shade and absorb CO₂.

• Rainfall and water cycle: Forests help clouds to form and keep local rainfall patterns more stable. In hilly regions, people often notice that when forest cover on slopes is cut for roads or farms, nearby springs either dry up or become seasonal instead of flowing all year.

• Soil protection and flood control: Roots bind the soil and fallen leaves form a soft layer that slows down rainwater. Where slopes have good forest cover, villages below usually see fewer landslides and less silt in their ponds and tanks. Where hills are bare, heavy rain quickly turns into destructive floods and soil erosion.

• Biodiversity support: Forests provide habitat, food and shelter to countless plants, animals, birds, insects and microorganisms. Losing forests means losing medicinal plants, pollinators (like bees) and predators that naturally control pests.

• Clean air and better micro-climate: Anyone who has walked from a busy main road into a dense park or small forest patch knows the difference – cooler air, less dust, easier breathing. Trees trap dust and absorb pollutants such as sulphur dioxide and nitrogen oxides, which is crucial in polluted cities.

• Support for local communities: Many rural and forest-dwelling families still depend on forests for fuelwood, fodder, fruits, fibre, and minor forest produce. When these resources degrade, people are forced to travel farther, spend more money, or even migrate for work.

Because population, energy use and infrastructure are all increasing, the pressure on forests is also increasing. At the same time, we now understand much better that forests are not just “timber stores” but life-support systems for climate, water, soil and biodiversity. That is why their ecological significance is especially important in the present context.

Question 2 (a). Why the Western Ghats are called a biodiversity hotspot

Unique features of the Western Ghats

The Western Ghats, running along the western coast of India from Gujarat to Kerala, are recognised internationally as a biodiversity hotspot because they combine three things: very high species richness, high endemism (species found nowhere else) and serious threats from human activity.

• Great variety of life: The region has tropical evergreen, semi-evergreen and moist deciduous forests, grasslands and shola ecosystems. This range of habitats supports thousands of plant, insect, bird, reptile and mammal species.

• High endemism: Many amphibians, reptiles and plants of the Western Ghats are endemic – they evolved there and are not found in any other part of the world. If these habitats disappear, those species may be lost forever.

• Favourable climate and topography: Heavy monsoon rainfall, steep slopes, deep valleys and varied micro-climates create many ecological “niches”, which encourages high biodiversity.

• Ecological services: Rivers originating in the Western Ghats (like Godavari, Krishna, Kaveri) provide water to millions of people for drinking, irrigation and power generation.

• High human pressure: Dams, mining, plantations, roads and urban expansion are rapidly fragmenting these forests. This combination of richness plus threat is exactly what the term “biodiversity hotspot” is meant to capture.

Question 2 (b). Why hydropower is considered a good energy option

Hydropower as a “clean” and renewable source

Hydropower uses the energy of falling or flowing water to generate electricity. Once a dam and power station are built, no coal or oil is burned to produce each unit of electricity, so operating emissions are very low.

• Renewable and domestic: As long as the monsoon and river flows continue, we can keep generating power without importing fuel. This improves energy security.

• Low running cost: The initial construction is expensive, but after that, the cost of generation per unit is usually low compared to many fossil-fuel plants.

• Flexible supply: Water stored in a reservoir can be released when demand is high. Many countries use hydropower to balance their power grid during peak demand or when solar/wind fluctuate.

• Multiple benefits: The same dam can provide irrigation, drinking water, flood moderation and sometimes tourism opportunities.

At the same time, real-life experience shows that hydropower projects can submerge forests, displace people and affect river ecosystems if not planned carefully. So hydropower is “one of the better” energy options mainly when social and ecological costs are properly assessed and reduced.

Question 2 (c). Growing importance of biomass as a renewable resource

Biomass in everyday life

Biomass simply means organic matter that can be used as a source of energy – for example, firewood, crop residues, animal dung, kitchen waste or specially grown energy crops.

• Locally available: In many villages, people already use cow dung cakes, crop residues and firewood for cooking. When managed properly (using efficient cookstoves or biogas plants), this local resource reduces dependence on LPG or kerosene.

• Biogas plants: A common real-life example is a family-size biogas plant using cow dung and kitchen waste. It produces clean gas for cooking and a nutrient-rich slurry that can be used as organic manure, reducing chemical fertiliser use.

• Waste to energy: In some towns, vegetable market waste or food waste from hostels and canteens is being converted into biogas or compost instead of being dumped in landfills.

• Carbon-neutral (if managed well): Plants absorb CO₂ when they grow, and release it when burned. If we replant and do not over-exploit biomass, the overall carbon balance can be close to neutral compared to fossil fuels.

Because biomass links energy production with waste management, soil fertility and rural livelihoods, its importance among renewable resources is increasing day by day.

Question 2 (d). How air pollution disturbs atmospheric processes

Air pollution and “misbehaving” atmosphere

Air pollution is not only a health issue; it also changes how the atmosphere behaves. Tiny particles and gases in polluted air can alter temperature, rainfall patterns and visibility.

• Heat balance and climate: Greenhouse gases like carbon dioxide and methane trap more heat, leading to global warming. Some particles (aerosols) can reflect sunlight and locally cool the surface, creating complex regional climate effects.

• Cloud formation and rainfall: Dust and smoke particles act as nuclei around which water droplets form. Too many such particles can result in many small droplets instead of fewer large ones, which may reduce effective rainfall or shift where rain falls.

• Smog and reduced visibility: In cities, a mix of pollutants and fog leads to smog. This reduces visibility, impacts transport and sometimes delays flights and trains, as seen in large cities during winter.

• Acid rain: Sulphur dioxide and nitrogen oxides react in the atmosphere to form acids, which fall as acid rain. This changes the chemistry of soils and water bodies and damages buildings and crops.

So air pollution interferes with the natural cycles of heat and moisture in the atmosphere, and its effects are visible from local smog episodes to global climate change.

Question 2 (e). Meaning of waste disposal and the need for segregation

Handling our waste smartly

Waste disposal means all the steps we use to handle waste after it is generated: collection, transportation, treatment (like composting, recycling, incineration) and final dumping or landfilling.

Waste segregation means separating waste at source into categories such as wet/biodegradable (food, peels, garden leaves), dry/recyclable (paper, plastic, metal, glass) and hazardous (batteries, medical waste, chemical containers).

• If kitchen waste is kept separate, it can be composted or used in a biogas plant. Many households and hostels now keep a small compost pit or bin.
• Clean, dry recyclables can be sold to kabadiwalas or sent to recycling units, reducing the need for new raw materials.
• Hazardous waste mixed with normal waste can harm rag-pickers, sanitation workers and the environment (for example, broken tube lights, syringes, chemical bottles).

In real life, cities that seriously implement segregation notice cleaner streets, less foul smell from dumps, lower landfill load and better working conditions for waste workers. Without segregation, even advanced treatment technologies struggle to work effectively.

Question 3. Human development, resource depletion and water laws

Why we needed water-related legislation in India

As human civilisation moved from simple farming to large industries, big cities and intensive agriculture, the pressure on rivers, lakes and groundwater increased sharply. Untreated industrial effluents, sewage and agricultural run-off began entering water bodies, making them unsafe for drinking, bathing or even aquatic life.

Real-life examples in India include rivers that pass through industrial zones and emerge black or foamy; lakes within cities choked by sewage; and handpumps in some areas giving contaminated water. Such situations showed that depending only on “goodwill” was not enough – legal controls were required.

Important national water-related laws were therefore introduced, especially:

• Water (Prevention and Control of Pollution) Act, 1974: This law aimed to prevent and control water pollution and maintain or restore the wholesomeness of water. It created Central and State Pollution Control Boards with powers to set standards, monitor water quality and give or refuse consent to industries for discharge.

• Environment (Protection) Act, 1986: Although broader than water, it gave the central government authority to issue rules and notifications for protecting water bodies and regulating hazardous substances.

Under these Acts, industries are expected to treat their wastewater, municipalities must plan sewage treatment, and violation can lead to fines or closure. While enforcement is still uneven, these legislations are a direct response to the way uncontrolled economic growth was degrading rivers and lakes. They represent society’s attempt to balance economic, social and cultural development with the basic environmental right to clean water.

Question 4. Human–environment relationship with biotic and abiotic examples

How people depend on both living and non-living components

Humans are part of ecosystems and interact continuously with biotic (living) and abiotic (non-living) components.

• Abiotic dependence: We need clean air (gases in the atmosphere), water (rivers, groundwater, rainfall), soil (for agriculture), sunlight and suitable temperature. For example, a farmer’s crop yield directly depends on soil fertility, rainfall and temperature. A city’s drinking water depends on the condition of its rivers and aquifers.

• Biotic dependence: We depend on plants for food, oxygen, fibres and medicines; on animals for milk, meat, leather and draught power; and on microorganisms for decomposing waste and making nutrients available in soil. For instance, pollinators like bees and butterflies are essential for fruit and seed production in many crops.

The relationship is two-way. Human activities like deforestation, overuse of fertilisers, pollution and overfishing change both abiotic and biotic components. Cutting a forest to build a township removes many plant and animal species (biotic), but it also changes local climate, soil moisture and water flow (abiotic).

When this relationship is harmonious – for example, in villages practicing soil and water conservation, mixed cropping and tree planting – the environment stays productive and healthy. When it is exploitative, we see issues like soil erosion, biodiversity loss and climate-related disasters.

Question 5. Role of biosphere reserves in conservation and human–nature balance

Biosphere reserves as “living laboratories”

Biosphere reserves are large areas that include core natural zones, buffer zones and transition zones where people live and work. Their goal is not only to protect wildlife and ecosystems but also to demonstrate how humans can live in harmony with nature.

• Core zone: Strictly protected area with minimal human activity, such as parts of national parks or wildlife sanctuaries. This helps conserve rare species and intact ecosystems.

• Buffer zone: Surrounds the core; limited activities like research, education, eco-tourism and some sustainable use are allowed.

• Transition zone: Area where people live, farm, graze animals or run small industries, but are encouraged to adopt environment-friendly practices.

In practice, biosphere reserves try to:

• Conserve biodiversity (plants, animals and genetic diversity).

• Support local livelihoods through sustainable forestry, agriculture, handicrafts and eco-tourism.

• Encourage research and monitoring so that we learn which practices work well.

For local people, this can mean training in improved farming, support for non-timber forest products, and involvement in protection committees. For nature, it means large connected habitats for wildlife, protected watersheds and less destructive land use. Thus, biosphere reserves are practical examples of how to maintain a balanced relationship between humans and the rest of the biosphere.

Question 6(a). Seed bank (about 60 words)

Seed bank – “insurance” for plant diversity

A seed bank is a facility where seeds of different plant species (especially crops and their wild relatives) are dried, treated and stored at low temperature for long periods. It acts like an insurance policy: if a variety disappears from the field due to disease, climate change or farmers shifting to new varieties, it can be regenerated from these stored seeds in future.

Question 6(b). Incineration (about 60 words)

Incineration – burning waste safely

Incineration is a waste treatment method in which solid waste is burned at very high temperatures in a specially designed furnace. This reduces the volume of waste and can destroy pathogens and some hazardous substances. In some plants the heat produced is used to generate electricity. However, if not properly controlled, incineration can release toxic gases and ash, so good pollution-control systems are essential.

Question 6(c). Biological Oxygen Demand (BOD) (about 60 words)

BOD – a measure of organic pollution

Biological Oxygen Demand (BOD) is the amount of dissolved oxygen that microorganisms need to break down organic matter present in water over a fixed time, usually five days. A high BOD value means there is a lot of organic pollution (like sewage or industrial effluents). Such water can become oxygen-poor, making it difficult for fish and other aquatic organisms to survive.

Question 6(d). Public health (about 60 words)

Public health – health of the community

Public health refers to organised efforts by society and government to protect and improve the health of the population rather than just treating individual patients. It includes safe drinking water, sanitation, vaccination, control of pollution, health education and preparedness for disease outbreaks. Environmental quality – air, water, housing, waste management – is a core part of public health.

Question 7(a). Lentic and lotic ecosystems with examples

Still water vs. flowing water systems

Lentic ecosystems are standing or still water bodies such as lakes, ponds, reservoirs and bogs. Water movement is minimal, so there are usually distinct zones (shoreline, open water, bottom). A village pond used for cattle washing and irrigation, or a city lake surrounded by parks, are common lentic examples.

Lotic ecosystems are flowing water bodies like streams, rivers and springs. The current is a key factor; it influences oxygen levels, sediment transport and the kind of plants and animals present. A fast-flowing mountain stream with clear, cold water and a large river like the Ganga or Narmada are typical lotic systems.

In real life, people depend on both: ponds for local irrigation and fish, rivers for large-scale water supply, transport and hydropower. Pollution or overuse in either type directly affects communities living nearby.

Question 7(b). Ecological succession and its types

How ecosystems change over time

Ecological succession is the natural, gradual process by which the species composition and structure of a community change over time until a relatively stable community (often called a climax community) is formed.

Primary succession: This begins on a surface where no soil and no life previously existed – for example, bare rock exposed after a volcanic eruption or a newly formed sand deposit. First, hardy pioneer species like lichens and mosses colonise the area, slowly form soil, then grasses, shrubs and finally trees appear over many years.

Secondary succession: This occurs where a community has been removed or disturbed but soil remains – for example, in an abandoned agricultural field or after a forest fire. Here succession is faster: grasses and herbs appear first, followed by shrubs and then a tree community.

In real landscapes, you can often see different stages side by side – a freshly abandoned field with weeds, an older one with shrubs and a long-abandoned one that looks like a young forest.

Question 7(c). Biocentrism and ecocentrism in human attitudes to nature

Looking beyond only human interests

Biocentrism is an ethical view that gives moral value to all living beings – humans, animals, plants and microorganisms. According to this view, humans are not superior; we are just one species among many, and we should avoid causing unnecessary harm to other forms of life.

Ecocentrism goes a step further. It values entire ecosystems – including non-living components such as rivers, mountains and soil – not just individual organisms. From this perspective, cutting a forest or damming a river is not judged only by how it affects people today, but also by how it impacts the integrity and long-term health of the whole ecosystem.

In daily life, a biocentric attitude might appear when someone opposes cruelty to animals or stops using products tested on animals. An ecocentric attitude appears when people support protecting a wetland even if they personally get no direct monetary benefit, because they see its ecological importance for birds, groundwater, flood control and future generations.

Question 7(d). Natural calamities and their types with examples

Major types of natural disasters

Natural calamities are extreme events caused by natural processes of the earth that lead to large-scale damage to life, property and the environment.

• Earthquakes: Sudden shaking of the ground due to movement of tectonic plates. Example: Earthquakes in Gujarat and Nepal that destroyed buildings and infrastructure.

• Floods: When rivers overflow or drainage systems fail, leading to waterlogging over large areas. Many Indian states experience floods during heavy monsoon rains.

• Cyclones: Intense storms with strong winds and heavy rainfall, mainly in coastal regions. For example, cyclones hitting Odisha, Andhra Pradesh and West Bengal.

• Droughts: Long periods of below-normal rainfall causing severe water shortage, crop failure and migration of people, as seen in parts of Rajasthan and other semi-arid regions.

• Tsunamis and landslides: Tsunamis are giant sea waves triggered by under-sea earthquakes; landslides occur on unstable slopes, especially where vegetation has been removed.

Human actions like deforestation, unplanned construction and poor drainage often make the impact of these natural events much worse.

Question 8. Causes of ozone depletion and effects of UV radiation

Why the ozone layer is thinning and why it matters

The ozone layer in the stratosphere acts like a shield by absorbing most of the sun’s harmful UVB radiation. Certain man-made chemicals have damaged this shield, causing ozone depletion.

Main causes of ozone depletion

• Chlorofluorocarbons (CFCs): Used earlier in refrigerators, air-conditioners, foam-making and aerosol sprays. These stable gases rise to the stratosphere, where UV light breaks them, releasing chlorine atoms that destroy ozone.

• Halons and other ozone-depleting substances: Halons (used in fire extinguishers) and chemicals like carbon tetrachloride and some cleaning solvents also release chlorine or bromine, which are very effective in breaking down ozone.

Effects of increased UV radiation

• On human and animal health: More UVB exposure can increase the risk of skin cancers, cataracts and other eye damage. It can also weaken the immune system, making people and animals more susceptible to infections.

• On plants: UVB can affect plant growth by damaging DNA and reducing photosynthesis. This may lead to lower crop yields and changes in natural plant communities.

• On microorganisms and aquatic life: Many microorganisms, especially phytoplankton at the top layer of oceans and lakes, are sensitive to UV radiation. If their population declines, the entire aquatic food chain, including fish, can be affected.

• On water and air quality and materials: Higher UV can change chemical reactions in air, affecting some pollutants. It can also speed up the breakdown of plastics, paints and other materials, increasing maintenance costs.

The global response through the Montreal Protocol has reduced the production of many ozone-depleting substances, showing how international cooperation can address such issues.

Question 9. Environmental education for all age groups

Why both young and old need environmental awareness

Environmental problems like air pollution, waste generation, climate change and water scarcity affect everyone, so awareness cannot be limited to school children alone.

• Younger generation: School and college students are at a formative age. When they learn about ecosystems, pollution and conservation through projects, field visits and eco-clubs, they develop habits like saving water, avoiding littering and questioning harmful practices. For example, students running a “no plastic day” in their campus can influence the behaviour of hundreds of peers and teachers.

• Older generation: Adults make most of the major decisions – building houses, buying vehicles, running industries, framing policies. If they are unaware, they may choose options that are cheap in the short term but very damaging in the long term, such as over-pumping groundwater or burning waste in open areas. Adult education programmes, TV/radio campaigns and community meetings can help them adopt better practices like rooftop rainwater harvesting or waste segregation at home.

Real-life experience shows that when children bring home ideas from school (like planting trees on birthdays) and elders support them with resources and decisions, the impact is much stronger. Environmental education for both generations creates a shared understanding and makes it easier to take collective action – from neighbourhood clean-ups to supporting eco-friendly policies.

Question 10. Water harvesting as a measure to combat drought

Capturing rain to face dry years

Drought occurs when rainfall is much lower than normal for a long period and surface as well as groundwater sources start drying up. One of the most practical ways to reduce the impact of drought is water harvesting – capturing rain where it falls and storing or recharging it for later use.

• Local storage: Villages and towns can collect rooftop run-off into tanks, ponds or underground storage structures. During dry months, this water can be used for drinking and domestic needs.

• Groundwater recharge: Structures such as recharge pits, percolation tanks and check dams allow rainwater to soak into the ground, raising the water table. When borewells in an area that has adopted such measures continue to yield water in summer, people immediately see the benefit.

• Traditional methods: Different regions of India have their own systems – johads and talaabs in Rajasthan, kuls in Himachal, bamboo drip irrigation in the North-East. These methods are low-cost, locally managed and well suited to local climate and culture.

• Urban examples: In some cities, regulations now require new buildings to have rainwater harvesting. Housing societies that implemented it often report fewer days of tanker dependence and lower water bills.

While water harvesting cannot prevent drought (which is mainly a climatic event), it greatly reduces its impact by improving local water availability, supporting crops and livestock, and reducing distress migration. That is why it is considered one of the most effective and community-friendly strategies to combat drought.