Our Environment-QnA

Q1: What is an ecosystem?

A system formed by interactions between living organisms and their physical surroundings.

Q2: Define trophic level.

Each step in a food chain where organisms obtain energy is called a trophic level.

Q3: What are producers?

Green plants that make food through photosynthesis.

Q4: Give an example of a decomposer.

Fungi such as mushrooms act as natural decomposers.

Q5: What is a biodegradable waste?

Waste that can be broken down naturally by microorganisms.

Q6: What is a non-biodegradable waste?

Waste that cannot be decomposed naturally and persists for long.

Q7: What is a food chain?

A sequence showing who eats whom in an ecosystem.

Q8: Give one example of a food chain.

Grass ? Grasshopper ? Frog ? Snake ? Eagle.

Q9: What is biological magnification?

Progressive increase of harmful chemicals at higher trophic levels.

Q10: Name one greenhouse gas.

Carbon dioxide.

Q11: What is ozone?

A protective gas layer in the atmosphere that absorbs UV radiation.

Q12: Why is ozone important?

It shields living beings from harmful ultraviolet rays.

Q13: What is meant by environment?

Everything surrounding us, including living and non-living components.

Q14: Define biodegradable pollutant.

Pollutants that microorganisms can break down.

Q15: Define non-biodegradable pollutant.

Pollutants that remain unchanged and accumulate in the environment.

Q1: What are the components of an ecosystem?

Biotic components (living organisms) and abiotic components (soil, air, water).

Q2: What are consumers?

Organisms that depend directly or indirectly on producers for food.

Q3: Why are decomposers essential?

They break down dead matter and recycle nutrients back into the soil.

Q4: What is the role of sunlight in an ecosystem?

It drives photosynthesis and provides energy for all food chains.

Q5: What are the two types of ecosystems?

Natural ecosystems (like forests) and artificial ecosystems (like crop fields).

Q6: How does energy flow in a food chain?

Energy flows from producers to herbivores, then to carnivores, and finally decomposers.

Q7: Why are food webs more realistic than food chains?

They show multiple feeding relationships, making them closer to real ecosystems.

Q8: What is the main cause of ozone depletion?

Excessive release of CFCs from refrigerators and aerosols.

Q9: What is waste management?

Systematic handling of waste to reduce pollution and promote recycling.

Q10: Give one harmful effect of plastic waste.

Plastics clog drains, pollute water bodies, and remain in nature for centuries.

Q1: Explain biological magnification with an example.

Harmful pesticides like DDT accumulate more at each trophic level; top predators receive the highest amount.

Q2: Describe the flow of energy in an ecosystem.

Energy enters through sunlight, captured by producers, transferred to consumers across trophic levels, and lost as heat at each step.

Q3: What are the differences between biodegradable and non-biodegradable waste?

Biodegradable waste decomposes naturally, while non-biodegradable waste persists, causing pollution and accumulation.

Q4: Explain how human activities disturb the natural ecosystem.

Deforestation, pollution, excessive use of chemicals, and waste generation disturb natural cycles and reduce biodiversity.

Q5: Discuss the importance of the ozone layer.

The ozone layer prevents UV radiation from reaching Earth, protecting humans, plants, animals, and maintaining ecological balance.

Q1: Describe an ecosystem with its components.

An ecosystem includes biotic components (plants, animals, microbes) and abiotic parts (soil, light, air). Both interact to form a functional unit.

Q2: What is a food web? Explain its significance.

A food web is a network of interconnected food chains. It stabilizes ecosystems by providing alternate food options.

Q3: How does excessive use of non-biodegradable waste affect the environment?

Non-biodegradable materials like plastics accumulate, pollute water, soil, and harm wildlife, leading to long-term ecological imbalance.

Q4: Explain ozone depletion and its effects on living organisms.

CFCs break down ozone molecules, thinning the protective layer, allowing harmful UV rays that cause skin cancer, cataracts, and reduced plant growth.

Q5: Write a detailed note on the need for proper waste disposal.

Proper waste disposal prevents pollution, reduces health risks, conserves resources, and ensures cleaner ecosystems through recycling and segregation.

Q1: What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

Trophic levels are the different steps or positions that organisms occupy in a food chain based on how they obtain energy. Each level represents a stage in the transfer of food energy—from plants to herbivores and then to carnivores. As we move up the trophic levels, the amount of available energy decreases because some energy is lost as heat at every step.

Example of a Food Chain: Grass \(\Rightarrow\) Grasshopper \(\Rightarrow\) Frog \(\Rightarrow\) Snake \(\Rightarrow\) Eagle

Trophic Levels in this Food Chain:
• 1st Trophic Level – Producers:
  Grass acts as the producer because it prepares its own food using sunlight.
• 2nd Trophic Level – Primary Consumers:
  The grasshopper is a herbivore and feeds directly on grass.
• 3rd Trophic Level – Secondary Consumers:
  The frog eats the grasshopper and functions as a secondary consumer.
• 4th Trophic Level – Tertiary Consumers:
  The snake feeds on the frog and represents the third-level carnivore.
• 5th Trophic Level – Top/Quaternary Consumer:
  The eagle sits at the top of this chain and preys on the snake.

Q2: What is the role of decomposers in the ecosystem?

Decomposers play a crucial role in maintaining the natural balance of an ecosystem. They break down the bodies of dead plants, dead animals, and animal wastes into simpler substances. This process returns essential nutrients—such as nitrogen, carbon, and minerals—back to the soil, making them available for use by plants again.

By carrying out this breakdown, decomposers prevent the accumulation of dead organic matter in the environment and keep nutrient cycles running smoothly. Without decomposers, ecosystems would soon become overloaded with waste, and soil fertility would gradually decline because nutrients would not be recycled.

Thus, decomposers act as nature’s recyclers, ensuring the continuous flow of nutrients and supporting the survival of all living organisms in the ecosystem.

Q3: Why are some substances biodegradable and some non-biodegradable?

Substances that can be broken down naturally by microorganisms such as bacteria and fungi are called biodegradable. These materials—like vegetable peels, paper, and cotton—are made of organic compounds that microorganisms can easily use as food. Their simple chemical structure allows them to decompose and return to the environment as harmless nutrients.

On the other hand, non-biodegradable substances cannot be broken down by natural decomposers. Materials such as plastics, metals, and glass have complex chemical structures that microorganisms do not recognize or cannot digest. As a result, these substances remain unchanged for many years and accumulate in the environment.

Thus, whether a substance is biodegradable or not depends on its chemical composition and the ability of decomposers to act on it.

Q4: Give any two ways in which biodegradable substances would affect the environment.

• They help maintain soil fertility:
  When biodegradable substances such as food waste or plant remains break down, they release nutrients like nitrogen and carbon back into the soil. These nutrients enrich the soil and support healthy plant growth.
• They may produce foul smell if not managed properly:
  If biodegradable waste accumulates in large quantities or decomposes in open spaces, it can produce unpleasant odours and attract insects or animals. This can create unhygienic conditions in the surroundings.

Q5: Give any two ways in which non-biodegradable substances would affect the environment.

1. They accumulate and cause long-term pollution:
   Non-biodegradable materials such as plastics and metals do not break down naturally. When they pile up in soil or water bodies, they remain there for years, leading to land pollution, water contamination, and harm to living organisms.
2. They can enter food chains and cause health hazards:
   When non-biodegradable chemicals, like pesticides, get absorbed by plants and smaller animals, they move into food chains. As they pass from one trophic level to another, their concentration increases, which can harm animals and even humans who consume contaminated food.

Q6: What is ozone and how does it affect any ecosystem?

Ozone is a gas made up of three oxygen atoms \(\mathrm{(O_3)}\). It is naturally found in the upper layers of the atmosphere, where it forms a protective shield around the Earth. This “ozone layer” absorbs harmful ultraviolet (UV) radiation coming from the Sun.

Ozone plays a vital role in maintaining the balance of ecosystems. By blocking most of the UV rays, it prevents excessive radiation from reaching the Earth’s surface. Without this protection, UV rays could damage the DNA of plants, animals, and humans. Too much UV exposure can reduce crop growth, harm aquatic life—especially plankton—and weaken the immune system of many organisms.

Thus, ozone helps safeguard living beings and supports the smooth functioning of ecosystems by limiting harmful solar radiation.

Q7: How can you help in reducing the problem of waste disposal? Give any two methods.

1. Segregating waste at home:
   By separating biodegradable waste (like kitchen scraps) from non-biodegradable waste (like plastics and glass), we make recycling and composting easier. Proper segregation reduces the load on landfills and ensures that useful materials are reused.
2. Reducing and reusing materials:
   Choosing reusable items—such as cloth bags, metal bottles, and durable containers—instead of single-use plastics helps cut down the amount of waste we generate. Reusing items not only reduces pollution but also conserves natural resources.