Most Important Questions of Our Environment

Our Environment Activities Based Questions NCERT Solutions

We often hear the term ‘environment’ in various contexts, from television and newspapers to conversations with people around us. Our elders reminisce about a time when the environment was different, while others emphasize the need to work in a healthy environment. Global summits regularly address environmental issues, highlighting their significance. In this chapter, we explore the interactions within the environment and how human activities impact these interactions.

What Happens When We Add Our Waste to the Environment?

In our daily lives, we generate various waste materials. Let’s understand the fate of these wastes through an activity.

Activity 13.1: Observing Waste Decomposition

1. Collect waste material from your home, such as kitchen waste, waste paper, empty medicine bottles, torn clothes, and broken footwear.
2. Bury this material in a pit or collect it in a bucket or flower pot and cover it with 15 cm of soil.
3. Keep the material moist and observe it at 15-day intervals.

Questions and Answers:

What materials remain unchanged over long periods?

Materials like plastics, glass, and metals remain unchanged over long periods because they are non-biodegradable.

What materials change their form and structure over time?

Materials like food waste, paper, and natural fabrics change their form and structure over time as they are biodegradable.

Of the materials that change, which ones change the fastest?

Food waste typically changes the fastest due to its high organic content and the action of decomposers like bacteria and fungi.

Understanding Biodegradability
Enzymes in our body digest food, but not all materials are broken down similarly. Human-made materials like plastics are resistant to biological processes. Substances that degrade through biological processes are biodegradable, while those that do not are non-biodegradable. Non-biodegradable substances persist in the environment and can harm ecosystems.

Activity 13.2: Research on Biodegradable and Non-Biodegradable Substances

1. Use the library or the internet to find more about biodegradable and non-biodegradable substances.
2. Discover how long various non-biodegradable substances last in the environment.
3. Investigate new types of biodegradable plastics and their environmental impact.

Questions and Answers:

Why are some substances biodegradable and some non-biodegradable?

Biodegradable substances can be broken down by natural processes involving microorganisms, while non-biodegradable substances resist decomposition due to their chemical structure.

Give any two ways in which biodegradable substances would affect the environment.

1. Biodegradable substances provide nutrients to the soil, enhancing fertility.
2. They help in the natural recycling of materials, maintaining ecological balance.

Give any two ways in which non-biodegradable substances would affect the environment.

1. Non-biodegradable substances can accumulate and cause pollution in landfills, oceans, and other natural habitats.
2. They pose a threat to wildlife, which may ingest or get entangled in them, leading to injury or death.

Ecosystem: What Are Its Components?

An ecosystem comprises all organisms (plants, animals, microorganisms, and humans) interacting with each other and their physical surroundings, maintaining a balance in nature. Ecosystems consist of biotic components (living organisms) and abiotic components (physical factors like temperature, rainfall, wind, soil, and minerals).

Activity 13.3: Designing an Aquarium

1. Think about what is needed to create a self-sustaining aquarium, including aquatic plants, animals, water, oxygen, and food.
2. Discuss why an aquarium needs to be cleaned and compare it to natural ecosystems like ponds and lakes.

Understanding Food Chains and Webs
Food chains represent a series of organisms feeding on one another, forming trophic levels. Producers (like green plants) are at the first trophic level, capturing solar energy and making it available for consumers. Consumers (herbivores, carnivores, omnivores, and parasites) depend on producers for sustenance. Decomposers (bacteria and fungi) break down dead organisms, recycling nutrients back into the ecosystem.

Activity 13.4: Exploring Food Chains

1. Discuss how organisms in an aquarium depend on each other.
2. Write the aquatic organisms in order of who eats whom, forming a food chain of at least three steps.
3. Debate whether any group of organisms is of primary importance and why.

Questions and Answers:

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

Trophic levels are the positions that organisms occupy in a food chain. An example of a food chain is:

1. Grass (Producer)
2. Grasshopper (Primary Consumer)
3. Frog (Secondary Consumer)
4. Snake (Tertiary Consumer)
5. Hawk (Quaternary Consumer)

What is the role of decomposers in the ecosystem?

Decomposers break down dead organic matter, returning essential nutrients to the soil, which are then reused by plants. This process recycles nutrients and maintains ecosystem balance.

How Do Our Activities Affect the Environment?

Human activities significantly impact the environment, causing issues like ozone layer depletion and waste disposal problems.

Ozone Layer and Its Depletion
Ozone (O3) in the upper atmosphere protects the Earth from harmful ultraviolet (UV) radiation. However, chemicals like chlorofluorocarbons (CFCs) have depleted the ozone layer, increasing UV radiation reaching the Earth’s surface. Efforts to reduce CFC emissions have been made, but continuous monitoring is necessary.

Activity 13.6: Research on Ozone Depletion

1. Investigate chemicals responsible for ozone depletion and their regulation.
2. Examine changes in the size of the ozone hole in recent years.

Managing Waste
Waste generation and disposal are significant environmental concerns. Proper waste management involves separating biodegradable and non-biodegradable waste and ensuring safe disposal.

Activity 13.7: Investigating Waste Management

1. Find out how waste is collected and treated in your locality.
2. Suggest methods to deal with classroom and household waste.

Questions and Answers:

What is ozone and how does it affect any ecosystem?

Ozone is a molecule composed of three oxygen atoms (O3). It forms a layer in the upper atmosphere that absorbs harmful UV radiation from the sun, protecting living organisms from DNA damage and other harmful effects.

How can you help in reducing the problem of waste disposal? Give any two methods.

1. Reduce, reuse, and recycle waste materials to minimize the amount of waste generated.
2. Compost biodegradable waste to create useful organic fertilizer, reducing landfill use and enriching soil.

Additional Information:

1. Biological Magnification: Harmful chemicals accumulate at each trophic level, with the highest concentration found in top-level consumers like humans.
2. Impact of Non-Biodegradable Waste: Persistent non-biodegradable materials, such as plastics, lead to soil and water pollution and pose a threat to wildlife and ecosystems.

Our Environment NCERT Solutions with Notes

Ecosystems

An ecosystem is a community of living organisms (plants, animals, and microbes) interacting with their non-living environment (air, water, and mineral soil) in a particular area. These interactions form a complex network of relationships that sustain life within the ecosystem.

Types of Ecosystems:

• Terrestrial Ecosystems: These are land-based ecosystems, such as forests, grasslands, deserts, and tundra.
• Aquatic Ecosystems: These are water-based ecosystems and can be further divided into freshwater (lakes, rivers, ponds) and marine ecosystems (oceans, coral reefs).

Examples of Ecosystems:

• Forest Ecosystem: Characterized by dense trees, a variety of plant and animal species, and a layered structure (canopy, understory, forest floor).
• Pond Ecosystem: Includes various aquatic plants, fish, amphibians, and microorganisms.

Components of an Ecosystem

Biotic Components: The living parts of an ecosystem, including:

• Producers (Autotrophs): Organisms like plants and algae that produce their own food through photosynthesis.
• Consumers (Heterotrophs): Organisms that consume other organisms for energy. They are further divided into:
• Primary Consumers (Herbivores): Animals that eat plants (e.g., deer, rabbits).
• Secondary Consumers (Carnivores): Animals that eat herbivores (e.g., snakes, wolves).
• Tertiary Consumers: Animals that eat secondary consumers (e.g., eagles, sharks).
• Decomposers: Organisms that break down dead organic matter (e.g., fungi, bacteria).

Abiotic Components: The non-living parts of an ecosystem, including:

• Physical Factors: Sunlight, temperature, precipitation, and soil.
• Chemical Factors: Nutrients, oxygen, carbon dioxide, and water.

Trophic Levels

Trophic levels represent the position an organism occupies in a food chain. Each level signifies a step in the flow of energy and nutrients.

Types of Trophic Levels:

1. Primary Producers: Organisms that produce their own food (e.g., plants, algae).
2. Primary Consumers: Herbivores that consume primary producers (e.g., rabbits, caterpillars).
3. Secondary Consumers: Carnivores that eat primary consumers (e.g., frogs, lions).
4. Tertiary Consumers: Carnivores that eat secondary consumers (e.g., hawks, killer whales).
5. Decomposers: Organisms that break down dead matter, recycling nutrients back into the ecosystem (e.g., bacteria, fungi).

Food Chain

A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another.

Example of a Food Chain:

• Grass → Grasshopper → Frog → Snake → Hawk

Food Web

A food web is a more complex network of interconnected food chains. It shows how different food chains are related within an ecosystem.

Example of a Food Web:

• In a forest ecosystem, a food web might include:
• Plants being eaten by insects and deer.
• Insects being eaten by birds and frogs.
• Birds and frogs being eaten by snakes.
• Snakes being eaten by hawks.

Ozone

Ozone (O3) is a molecule composed of three oxygen atoms. It exists in two layers of the Earth’s atmosphere: the stratosphere and the troposphere.

Types of Ozone:

• Stratospheric Ozone: Found in the stratosphere, this ozone layer absorbs and scatters the sun’s harmful ultraviolet radiation, protecting living organisms.
• Tropospheric Ozone: Found in the troposphere, this ground-level ozone is a major component of smog and can be harmful to respiratory health.

Ozone Depletion:

• Caused by man-made chemicals like chlorofluorocarbons (CFCs), which break down ozone molecules, leading to the thinning of the ozone layer.
• Consequences: Increased UV radiation reaching the Earth, leading to higher rates of skin cancer, cataracts, and reduced crop yields.

Steps to Protect the Ozone Layer:

• Montreal Protocol: An international treaty to phase out the production and use of ozone-depleting substances.
• Use of Alternatives: Promoting the use of alternative chemicals that do not harm the ozone layer.

Exercises

The term Ecosystem was introduced by:

a) Miller

b) Haldane

c) Tansley

d) Darwin

Answer:
c) Tansley

In a food chain, there is:

a) Bidirectional flow of energy.

b) Zig zag flow of energy.

c) Multi directional flow of energy.

d) Unidirectional flow of energy.

Answer:
d) Unidirectional flow of energy.

Nature’s cleaners are:

a) Producers

b) Consumers

c) Decomposers

d) Carnivores

Answer:
c) Decomposers

Which of the following groups contain only biodegradable items?

a) Grass, flowers and leather

b) Grass, wood and plastic

c) Fruit-peels, cake and lime-juice

d) Cake, wood and grass

Answer:
a) Grass, flowers and leather
c) Fruit-peels, cake and lime-juice
d) Cake, wood and grass

Which of the following constitute a food-chain?

a) Grass, wheat and mango

b) Grass, goat and human

c) Goat, cow and elephant

d) Grass, fish and goat

Answer:
b) Grass, goat and human

Which of the following are environment-friendly practices?

a) Carrying cloth-bags to put purchases in while shopping

b) Switching off unnecessary lights and fans

c) Walking to school instead of getting your mother to drop you on her scooter

d) All of the above

Answer:
d) All of the above

What will happen if we kill all the organisms in one trophic level?

If all organisms in one trophic level are killed, it will disrupt the entire food chain. The organisms in the trophic level below will increase in number due to a lack of predators, leading to overconsumption of their food resources. Meanwhile, the organisms in the trophic level above will starve due to a lack of food, potentially leading to their extinction.

Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

Yes, the impact will be different for different trophic levels. Removing producers (first trophic level) will collapse the ecosystem as they form the base of all food chains. Removing primary consumers (second trophic level) will cause producers to overgrow and secondary consumers to starve. Removing any trophic level causes imbalance, and no trophic level can be removed without causing damage to the ecosystem.

What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

Biological magnification refers to the process where the concentration of harmful substances increases in organisms at higher trophic levels in a food chain. Yes, the levels of magnification will be higher at the top trophic levels because these organisms consume many smaller organisms, each containing the pollutant, leading to a higher concentration in their bodies.

What are the problems caused by the non-biodegradable wastes that we generate?

Non-biodegradable wastes cause several problems:

• They accumulate in the environment, leading to pollution.
• They can harm wildlife through ingestion or entanglement.
• They do not decompose, taking up space in landfills and releasing toxic substances into the soil and water.

If all the waste we generate is biodegradable, will this have no impact on the environment?

Even if all waste is biodegradable, it can still impact the environment if not managed properly. Excessive biodegradable waste can lead to problems like foul odors, increased pest populations, and methane emissions during decomposition, which is a potent greenhouse gas contributing to climate change.

Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

Damage to the ozone layer is concerning because it protects life on Earth from harmful ultraviolet (UV) radiation. Increased UV exposure can lead to skin cancer, cataracts, and reduced agricultural productivity. Steps to limit this damage include international agreements like the Montreal Protocol, which aims to phase out the production and use of ozone-depleting substances like chlorofluorocarbons (CFCs).