Practicing Our Environment Class 10 Science MCQs helps students revise Chapter 15 effectively and build a clear understanding of important concepts like ecosystem, food chain, energy flow, waste management, and environmental balance. These questions are prepared according to the latest CBSE Board exam pattern and focus on NCERT-based concepts, application skills, and quick revision.
This chapter includes many topics where students need strong conceptual clarity instead of simple memorization. Solving different types of MCQs helps you improve accuracy, identify weak areas, and prepare better for competency-based questions.
For complete Science preparation, you can also explore Class 10 Science MCQs and practice chapter-wise Class 10 MCQs to strengthen your overall exam readiness.
Our Environment Class 10 Science MCQs with Answers
Before solving the questions, quickly revise the main concepts of the chapter. These MCQs will help you check your understanding of ecosystems, food chains, environmental issues, and important NCERT concepts frequently asked in exams.
Q. A student keeps two identical plants in separate containers. One plant receives sunlight daily, while the other is kept in a dark room. After some days, the plant kept in darkness becomes weak. Which conclusion explains this observation?
A. Plants need sunlight for food formation
B. Soil provides all energy to plants
C. Plants survive without photosynthesis
D. Darkness increases plant growth
Answer: A
Explanation:
Green plants use sunlight during photosynthesis to prepare food. Sunlight acts as the main energy source for producers, and this energy is passed to other organisms through food chains.
Q. In a grassland ecosystem, the number of organisms usually decreases from producers to top consumers. What is the main reason behind this pattern?
A. Producers consume all nutrients
B. Energy reduces at each level
C. Carnivores need no energy
D. Decomposers stop energy flow
Answer: B
Explanation:
Only a small part of energy is transferred from one trophic level to the next. Due to continuous energy loss, fewer organisms can be supported at higher trophic levels.
Q. Which statement correctly explains the flow of energy in an ecosystem?
A. Energy moves in cycles
B. Energy flows only one way
C. Energy returns from consumers
D. Energy increases at each level
Answer: B
Explanation:
Energy enters an ecosystem through producers and moves towards consumers. It does not return back because much of it is lost as heat during life processes.
Q. If plants in a food chain store 20,000 J of energy, how much energy will be available to herbivores according to the 10% law?
A. 20 J
B. 200 J
C. 2,000 J
D. 20,000 J
Answer: C
Explanation:
According to the 10% law, only about 10% energy passes to the next trophic level. Therefore, herbivores will receive 10% of 20,000 J, which is 2,000 J.
Q. A food chain is shown below:
Grass → Deer → Tiger
What will most likely happen if the deer population suddenly decreases?
A. Grass will decrease rapidly
B. Tigers may face food shortage
C. Tigers will become producers
D. Grass will stop photosynthesis
Answer: B
Explanation:
Deer act as food for tigers in this food chain. A decrease in deer population reduces food availability for tigers, which can affect their survival.
Q. Assertion (A): Food chains usually contain only three to four trophic levels.
Reason (R): A large amount of energy is lost while moving from one trophic level to another.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true, but R is false
D. A is false, but R is true
Answer: A
Explanation:
Food chains are limited because energy keeps decreasing at each step. After a few trophic levels, very little energy remains to support more organisms.
Q. A pond contains algae, small insects, fish and birds. Which organism acts as the entry point of energy into this ecosystem?
A. Birds
B. Fish
C. Insects
D. Algae
Answer: D
Explanation:
Algae are producers because they perform photosynthesis. They convert solar energy into food energy, which supports other organisms in the pond ecosystem.
Q. Why are plants called producers in an ecosystem?
A. They consume animals
B. They prepare their own food
C. They recycle dead matter
D. They absorb all oxygen
Answer: B
Explanation:
Plants contain chlorophyll and prepare food from carbon dioxide and water using sunlight. Therefore, they are called producers or autotrophs.
Q. A forest has several interconnected food chains instead of a single food chain. What advantage does this provide?
A. More ecosystem stability
B. Complete energy recycling
C. Removal of all predators
D. No need for producers
Answer: A
Explanation:
Interconnected food chains form a food web. Food webs provide alternative food sources and help maintain balance if one organism decreases.
Q. A farmer uses chemicals that destroy most insects in a field. Birds depending on those insects also start decreasing. What does this show?
A. Organisms are interconnected
B. Birds produce their own food
C. Chemicals increase biodiversity
D. Insects are not important
Answer: A
Explanation:
Different organisms in an ecosystem depend on each other through food relationships. A change in one population can affect other connected organisms.
Q. A pesticide used in a crop field enters a nearby lake through rainwater. Which organism is likely to have the highest pesticide concentration?
A. Aquatic plants
B. Small insects
C. Small fishes
D. Fish-eating birds
Answer: D
Explanation:
Non-biodegradable chemicals increase in concentration at each trophic level. Since fish-eating birds occupy the highest level in this food chain, they accumulate the maximum amount of pesticide.
Q. A harmful chemical enters the following food chain:
Grass → Grasshopper → Frog → Snake
Which organism will contain the highest amount of this chemical after a long time?
A. Grass
B. Grasshopper
C. Frog
D. Snake
Answer: D
Explanation:
The concentration of non-biodegradable substances increases as they move up the food chain. This process is called biological magnification, causing top consumers like snakes to accumulate more toxins.
Q. Assertion (A): Humans may receive high amounts of harmful pesticides through food chains.
Reason (R): Non-biodegradable chemicals can accumulate and increase at higher trophic levels.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true, but R is false
D. A is false, but R is true
Answer: A
Explanation:
Humans often occupy higher trophic levels in food chains. Persistent chemicals accumulate through biomagnification and may reach harmful concentrations in humans.
Q. A lake sample shows the following pesticide concentration:
Water plants: 0.02 ppm
Small fish: 2 ppm
Large fish: 15 ppm
What does this data represent?
A. Energy transfer
B. Food production
C. Biomagnification
D. Decomposition
Answer: C
Explanation:
The increasing pesticide concentration from producers to higher consumers shows biomagnification. It happens because some chemicals cannot be easily broken down or removed from organisms.
Q. Why are non-biodegradable pesticides considered more harmful than biodegradable substances?
A. They disappear quickly
B. They accumulate in organisms
C. They increase oxygen levels
D. They become plant nutrients
Answer: B
Explanation:
Non-biodegradable pesticides remain in the environment for a long time and accumulate inside living organisms, causing harmful effects through food chains.
Q. Farmers are advised to reduce the excessive use of chemical pesticides. Which reason best supports this advice?
A. They stop photosynthesis directly
B. They may enter food chains
C. They increase soil minerals
D. They produce more rainfall
Answer: B
Explanation:
Excessive pesticide use can allow harmful chemicals to enter ecosystems. These chemicals may move through food chains and affect animals and humans.
Q. A person regularly eats large predatory fish from polluted water bodies. Which risk is most likely associated with this habit?
A. Higher toxin accumulation
B. Faster digestion process
C. Increased oxygen intake
D. Better mineral recycling
Answer: A
Explanation:
Large predatory fish are usually at higher trophic levels and may contain more accumulated pollutants due to biomagnification. Consuming them frequently can increase toxin exposure.
Q. Which property of a chemical makes it more likely to cause biological magnification?
A. Easily decomposed
B. Quickly removed
C. Long-lasting in nature
D. Used by producers
Answer: C
Explanation:
Chemicals that remain unchanged for a long time and cannot be easily degraded tend to accumulate in organisms and show biological magnification.
Q. A scientist finds that an insecticide is stored in animal body fat and is not removed easily. What will be its possible effect?
A. It may magnify in food chains
B. It will improve biodiversity
C. It will become oxygen
D. It will act as food
Answer: A
Explanation:
Chemicals stored inside body tissues can remain for a long time. When predators consume affected organisms, these chemicals move upward and increase in concentration.
Q. Which method can help reduce the entry of harmful chemicals into food chains?
A. Using more pesticides
B. Burning all crop plants
C. Promoting organic farming
D. Removing all consumers
Answer: C
Explanation:
Organic farming reduces dependence on synthetic chemicals. This lowers the chances of harmful substances entering ecosystems and causing biomagnification.
Q. The ozone layer protects living organisms on Earth mainly by absorbing which harmful radiation?
A. Infrared rays
B. Ultraviolet rays
C. Radio waves
D. Visible light
Answer: B
Explanation:
The ozone layer absorbs harmful ultraviolet (UV) radiation from the Sun. This protection reduces the risk of damage to living cells and helps maintain life on Earth.
Q. Oxygen molecules present in the upper atmosphere help in ozone formation. Which process correctly explains the first step?
A. Oxygen combines with water
B. Oxygen absorbs UV radiation
C. Oxygen changes into carbon dioxide
D. Oxygen reacts with nitrogen
Answer: B
Explanation:
High-energy UV radiation breaks oxygen molecules (O₂) into free oxygen atoms. These oxygen atoms combine with oxygen molecules to form ozone (O₃).
Q. Assertion (A): Chlorofluorocarbons (CFCs) damage the ozone layer.
Reason (R): CFCs release chlorine atoms that break down ozone molecules.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true, but R is false
D. A is false, but R is true
Answer: A
Explanation:
CFCs reach the upper atmosphere and release chlorine atoms under UV radiation. These chlorine atoms destroy ozone molecules, leading to ozone layer depletion.
Q. A student compares two waste materials: vegetable peels and plastic wrappers. After several months in soil, only vegetable peels decompose. What does this show?
A. Plastic is biodegradable
B. Microbes digest all materials
C. Vegetable peels are biodegradable
D. Plastic improves soil quality
Answer: C
Explanation:
Vegetable peels are organic materials that microorganisms can break down naturally. Plastics do not decompose easily because they are non-biodegradable.
Q. Why do most plastics remain in the environment for many years?
A. They absorb sunlight
B. Microbes cannot easily break them
C. They contain extra oxygen
D. Animals avoid eating them
Answer: B
Explanation:
Most plastics contain complex synthetic structures that microorganisms cannot easily decompose. Therefore, they remain in the environment for a very long time.
Q. A city separates kitchen waste from plastic waste before disposal. What is the main benefit of this practice?
A. Faster plastic production
B. Better waste management
C. More chemical pollution
D. Less decomposition
Answer: B
Explanation:
Waste segregation allows biodegradable waste to be composted and non-biodegradable waste to be recycled or treated properly, reducing environmental pollution.
Q. Which organisms play the most important role in recycling nutrients from dead plants and animals?
A. Producers
B. Herbivores
C. Decomposers
D. Carnivores
Answer: C
Explanation:
Decomposers like bacteria and fungi break down dead organic matter. They return nutrients back to the soil, making them available for plants again.
Q. A school replaces single-use plastic bottles with reusable steel bottles. Which environmental problem does this mainly reduce?
A. Soil formation
B. Plastic pollution
C. Ozone formation
D. Photosynthesis rate
Answer: B
Explanation:
Using reusable bottles reduces the production and disposal of single-use plastics. This helps decrease long-term plastic pollution in the environment.
Q. The Montreal Protocol was introduced mainly to control substances responsible for:
A. Soil erosion
B. Ozone depletion
C. Noise pollution
D. Water shortage
Answer: B
Explanation:
The Montreal Protocol is an international agreement aimed at reducing ozone-depleting substances, especially CFCs, to protect the ozone layer.
Q. A waste container filled with food remains starts producing a bad smell after a few days. What is the most suitable explanation?
A. Food converts into plastic
B. Decomposition is occurring
C. Oxygen production increases
D. Ozone is being released
Answer: B
Explanation:
Microorganisms break down organic waste through decomposition. During this process, gases may be released, which can produce an unpleasant smell.
Q. Case-Based Question
A group of students studied waste management in their school. They observed that paper waste was sent for recycling, food waste was converted into compost, and plastic waste was collected separately.
Which conclusion can be drawn from this practice?
A. All waste behaves similarly
B. Waste segregation reduces pollution
C. Plastics become natural fertilizers
D. Composting stops decomposition
Answer: B
Explanation:
Separating different types of waste allows proper treatment methods like recycling and composting. This reduces pollution and supports sustainable waste management.
Q. Which daily habit best follows the idea of reducing environmental damage?
A. Using disposable plastics daily
B. Burning household garbage
C. Carrying reusable bags
D. Throwing mixed waste outside
Answer: C
Explanation:
Reusable bags reduce dependence on single-use plastics. Such small lifestyle changes help decrease waste generation and protect the environment.
Quick Overview of Chapter 15 Our Environment
Chapter 15 Our Environment from Class 10 Science explains the relationship between living organisms and their surroundings. It helps students understand how ecosystems work and how human activities can disturb environmental balance.
This chapter mainly focuses on:
| Concept | What You Learn |
|---|---|
| Ecosystem | Interaction between living and non-living components |
| Food Chain | Transfer of energy between organisms |
| Trophic Levels | Position of organisms in a food chain |
| Decomposers | Role of microorganisms in recycling nutrients |
| Waste Management | Effects of biodegradable and non-biodegradable substances |
| Ozone Layer | Importance of ozone and causes of depletion |
Understanding these concepts makes solving MCQs easier because most questions test practical understanding rather than memorization.
Why Practice Our Environment Class 10 Science MCQs?
Practicing MCQs from this chapter helps you identify whether you can apply concepts correctly in different situations. CBSE exams now focus more on understanding, reasoning, and competency-based questions.
Regular MCQ practice helps you:
- Revise the complete chapter in less time
- Understand important NCERT concepts clearly
- Improve accuracy in objective questions
- Prepare for assertion-reason and case-based questions
- Avoid confusion between similar environmental terms
- Build confidence before exams
Since topics like ecosystem, food chain, and environmental conservation are connected with real-life examples, practicing different question patterns improves your overall Science preparation.
Topics Covered in Our Environment Class 10 MCQs
The MCQ practice of Chapter 15 includes all important topics from the latest CBSE Class 10 Science syllabus.
| Topic | Important MCQ Areas |
|---|---|
| Components of Ecosystem | Producers, consumers, decomposers, abiotic factors |
| Food Chain and Food Web | Energy flow, organism relationships, examples |
| Trophic Levels | Energy transfer and 10 percent law |
| Environmental Balance | Human impact on ecosystems |
| Biodegradable Waste | Natural breakdown and role of decomposers |
| Non-Biodegradable Waste | Pollution and harmful effects |
| Ozone Layer | Ozone depletion, CFCs, protection methods |
These topics build the foundation for solving both direct and application-based MCQ questions.
Quick Revision Notes for Our Environment Class 10
Before attempting MCQs, revise these important points:
- An ecosystem includes all living organisms and physical surroundings interacting together.
- Plants act as producers because they prepare their own food through photosynthesis.
- Animals depend directly or indirectly on producers and are called consumers.
- Decomposers break down dead plants and animals and help recycle nutrients.
- A food chain represents the flow of energy from one organism to another.
- Energy decreases at each trophic level according to the 10 percent law.
- Biodegradable substances can be naturally decomposed by microorganisms.
- Non-biodegradable substances remain in the environment for a long time.
- The ozone layer protects living organisms from harmful ultraviolet radiation.
- Chemicals like CFCs contribute to ozone layer depletion.
Smart Tips to Solve Class 10 Our Environment MCQs
Use these simple methods while practicing Chapter 15 questions:
Understand the concept first
Do not only memorize definitions. Understand how organisms interact in an ecosystem because many questions are situation-based.
Learn examples from NCERT
Examples of food chains, decomposers, and waste materials are commonly used in MCQs.
Focus on keywords in questions
Words like “incorrect statement”, “main reason”, “best example”, or “most suitable option” can completely change the answer.
Compare similar concepts
Prepare differences between:
Biodegradable and non-biodegradable substances
Food chain and food web
Producers and consumers
Natural and artificial ecosystems
Practice mixed questions
Solve direct, competency-based, and assertion-reason MCQs to prepare for different exam formats.
Common Mistakes Students Make in Our Environment MCQs
Many students understand the chapter but lose marks because of small conceptual mistakes.
Avoid these common errors:
| Mistake | Correct Understanding |
|---|---|
| Thinking energy is recycled in ecosystems | Energy flows in one direction |
| Confusing food chains and food webs | Food webs contain multiple connected food chains |
| Forgetting the role of decomposers | They recycle nutrients by breaking organic matter |
| Considering all waste harmful equally | Biodegradable and non-biodegradable wastes behave differently |
| Ignoring NCERT examples | CBSE questions are mostly based on NCERT concepts |
Careful reading and regular practice can help reduce these mistakes.
Important Exam Focus Areas from Our Environment Class 10
For better CBSE exam preparation, pay extra attention to these areas:
- Definition and examples of ecosystems
- Producers, consumers, and decomposers
- Different trophic levels in food chains
- Flow of energy in an ecosystem
- 10 percent energy transfer law
- Biological magnification concept
- Effects of non-biodegradable waste
- Causes and impact of ozone layer depletion
- Environmental conservation methods
These concepts have a higher chance of appearing in objective and competency-based questions.
Conclusion
Practicing Our Environment Class 10 Science MCQs helps students revise Chapter 15 effectively and build a strong understanding of environmental concepts. Topics like ecosystem, food chain, waste management, and ozone protection are important not only for exams but also for understanding real-world environmental issues. Revise the concepts carefully, practice different question types, and focus on understanding the logic behind every answer for better CBSE Science preparation.
