Our Environment - VSA Questions

CBSE Class 10 Biology: Our Environment - Part 2: VSA Questions

Top 25 VSA Questions with Answers | Latest CBSE Pattern

1. MCQ 2. VSA 3. SA 4. LA 5. Assertion-Reason 6. Case Study 7. Concepts 8. One-Shot Revision

Welcome to Part 2 of our 8-part series on the chapter Our Environment. This post contains the top 25 Very Short Answer (VSA) Questions, perfect for 1-mark answers in your board exams.

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Top 25 VSA Questions - Our Environment

Question 1: Ecosystem

CBSE PYQ 2020

What is an ecosystem?

Answer: An ecosystem is a functional unit of nature consisting of all living organisms (biotic components) in an area interacting with their non-living (abiotic) physical environment.

Question 2: Food Chain

CBSE PYQ 2022

What is a food chain?

Answer: A food chain is a linear sequence of organisms where nutrients and energy are transferred from one organism to another, starting from producers and ending at top consumers.

Question 3: Producers

Define producers.

Answer: Producers are organisms (like plants and algae) that can produce their own food from simple inorganic substances like carbon dioxide and water, using light energy (photosynthesis).

Question 4: Decomposers

CBSE PYQ 2023

What is the role of decomposers in the ecosystem?

Answer: Decomposers (like bacteria and fungi) break down dead organic matter and animal waste into simple inorganic nutrients, returning them to the soil and thus helping in nutrient recycling.

Question 5: Trophic Level

What is meant by a trophic level?

Answer: Each step or level in a food chain where the transfer of energy occurs is called a trophic level. (e.g., Producers = T1, Primary Consumers = T2).

Question 6: 10% Law

CBSE PYQ 2024

State the 10% energy law.

Answer: The 10% law states that only about 10% of the energy from one trophic level is transferred to the next higher trophic level. The remaining 90% is lost as heat during metabolic processes.

Question 7: Ozone Layer

CBSE PYQ 2022

What is the function of the ozone layer?

Answer: The ozone layer, present in the stratosphere, protects life on Earth by absorbing most of the harmful ultraviolet (UV) radiation coming from the sun.

Question 8: Ozone Depletion

CBSE PYQ 2020

Name the main chemical responsible for ozone layer depletion.

Answer: Chlorofluorocarbons (CFCs).

Question 9: Biodegradable Waste

What are biodegradable wastes? Give one example.

Answer: Wastes that can be broken down into harmless natural substances by microorganisms (decomposers) are called biodegradable wastes. Example: Vegetable peels, paper.

Question 10: Non-Biodegradable

CBSE PYQ 2023

What are non-biodegradable wastes? Give one example.

Answer: Wastes that cannot be broken down by microorganisms into harmless substances are called non-biodegradable wastes. Example: Plastic, glass.

Question 11: Food Web

Define a food web.

Answer: A food web is a network of interconnected food chains within an ecosystem, showing the multiple feeding relationships among different organisms.

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Question 12: Biomagnification

CBSE PYQ 2022

What is biomagnification?

Answer: Biomagnification is the process by which the concentration of harmful, non-biodegradable chemical substances (like pesticides) increases at each successive trophic level in a food chain.

Question 13: Artificial Ecosystem

CBSE PYQ 2024

Give two examples of an artificial ecosystem.

Answer: Two examples are an aquarium and a crop field (or garden).

Question 14: Energy Flow

CBSE PYQ 2023

Why is the flow of energy in an ecosystem unidirectional?

Answer: Energy flows from the sun to producers, then to consumers, and is lost as heat at each step. It cannot be transferred back from a higher trophic level to a lower one.

Question 15: Trophic Level Limit

Why are food chains generally short, consisting of only 3-4 trophic levels?

Answer: Due to the 10% energy law, the amount of energy available at each successive trophic level decreases drastically. There is not enough energy to support a large population at higher levels.

Question 16: Biotic Components

Name the three types of biotic components in an ecosystem.

Answer: Producers, Consumers, and Decomposers.

Question 17: Abiotic Components

Name any two abiotic components of an ecosystem.

Answer: Air and Water (or Sunlight, Soil, Temperature).

Question 18: Primary Consumers

What are primary consumers? Give one example.

Answer: Primary consumers are organisms that feed on producers (plants). They are also called herbivores. Example: Deer, Goat.

Question 19: Energy Source

What is the ultimate source of energy for all ecosystems?

Answer: The Sun (Solar energy).

Question 20: UV Radiation

CBSE PYQ 2025

Name one disease caused by the depletion of the ozone layer.

Answer: Skin cancer (or cataracts).

Question 21: Ozone Formula

What is the chemical formula for ozone?

Answer: O₃

Question 22: Waste Management

CBSE PYQ 2023

Why is it better to use paper bags than plastic bags?

Answer: Because paper bags are biodegradable, whereas plastic bags are non-biodegradable and cause pollution.

Question 23: UNEP

What does UNEP stand for?

Answer: United Nations Environment Programme.

Question 24: Top Carnivore

In the food chain: Grass -> Deer -> Lion, which organism will have the maximum concentration of harmful chemicals?

Answer: The Lion, due to biomagnification.

Question 25: Trophic Level T2

CBSE PYQ 2024

What kind of organisms are found at the second trophic level (T2)?

Answer: Primary consumers (Herbivores).