Our Environment | Important Definitions and Key Concepts
Class 10 Science | Chapter – Our Environment | Definitions • Concepts • Exam Revision
🌱 Important Definitions – Our Environment
1. Environment
Environment – पर्यावरण
English: The environment includes all living and non-living components surrounding an organism and their interactions.हिन्दी: किसी जीव के चारों ओर उपस्थित सभी जैविक और अजैविक घटकों तथा उनके पारस्परिक संबंधों को पर्यावरण कहते हैं।
2. Ecosystem
Ecosystem – पारितंत्र
English: An ecosystem is a functional unit in which living organisms interact with one another and with non-living components of their surroundings.हिन्दी: पारितंत्र एक क्रियात्मक इकाई है जिसमें जीवित organisms तथा उनके आसपास के अजैविक घटक परस्पर क्रिया करते हैं।
3. Biotic Components
Biotic Components – जैविक घटक
English: The living components of an ecosystem are called biotic components.Examples: Plants, animals, bacteria, fungi.
हिन्दी: पारितंत्र के जीवित घटकों को जैविक घटक कहते हैं।
4. Abiotic Components
Abiotic Components – अजैविक घटक
English: Non-living physical and chemical components of an ecosystem are called abiotic components.Examples: Air, water, soil, sunlight, temperature and minerals.
हिन्दी: पारितंत्र के निर्जीव भौतिक एवं रासायनिक घटकों को अजैविक घटक कहते हैं।
5. Producer
Producer – उत्पादक
English: Organisms that prepare their own food, generally through photosynthesis, are called producers.Examples: Green plants, algae.
हिन्दी: जो जीव अपना भोजन स्वयं बनाते हैं, सामान्यतः प्रकाश संश्लेषण द्वारा, उन्हें उत्पादक कहते हैं।
6. Consumer
Consumer – उपभोक्ता
English: Organisms that obtain food from other organisms are called consumers.Examples: Deer, rabbit, lion, human beings.
हिन्दी: जो जीव अपना भोजन अन्य जीवों से प्राप्त करते हैं, उन्हें उपभोक्ता कहते हैं।
7. Primary Consumer
Primary Consumer – प्राथमिक उपभोक्ता
English: Organisms that directly feed on producers are called primary consumers.Examples: Cow, deer, rabbit, grasshopper.
हिन्दी: जो जीव सीधे उत्पादकों को खाते हैं, उन्हें प्राथमिक उपभोक्ता कहते हैं।
8. Secondary Consumer
Secondary Consumer – द्वितीयक उपभोक्ता
English: Organisms that feed on primary consumers are called secondary consumers.Examples: Frog, lizard, some fish.
हिन्दी: प्राथमिक उपभोक्ताओं को खाने वाले जीव द्वितीयक उपभोक्ता कहलाते हैं।
9. Tertiary Consumer
Tertiary Consumer – तृतीयक उपभोक्ता
English: A consumer that feeds on organisms at lower consumer levels and occupies a higher trophic level.Examples: Eagle, hawk and some large predators.
हिन्दी: उच्च पोषण स्तर पर स्थित और निम्न उपभोक्ताओं को खाने वाले जीव तृतीयक उपभोक्ता कहलाते हैं।
10. Decomposer
Decomposer – अपघटक
English: Organisms that break down dead plants, animals and organic wastes into simpler substances are called decomposers.Examples: Many bacteria and fungi.
हिन्दी: मृत पौधों, जीवों और जैविक पदार्थों को सरल पदार्थों में तोड़ने वाले जीव अपघटक कहलाते हैं।
11. Food Chain
Food Chain – खाद्य श्रृंखला
English: A food chain is a sequence of organisms through which food and energy are transferred.Example: Grass → Grasshopper → Frog → Snake → Eagle
हिन्दी: जीवों की वह क्रमिक श्रृंखला जिसमें भोजन और ऊर्जा एक जीव से दूसरे जीव में स्थानांतरित होती है, खाद्य श्रृंखला कहलाती है।
12. Food Web
Food Web – खाद्य जाल
English: A network of interconnected food chains is called a food web.हिन्दी: अनेक परस्पर जुड़ी हुई खाद्य श्रृंखलाओं के जाल को खाद्य जाल कहते हैं।
13. Trophic Level
Trophic Level – पोषण स्तर
English: Each step or position occupied by an organism in a food chain is called a trophic level.हिन्दी: खाद्य श्रृंखला में प्रत्येक पोषणात्मक स्तर को पोषण स्तर कहते हैं।
14. Energy Flow
Energy Flow – ऊर्जा प्रवाह
English: The movement of energy from the Sun to producers and then through successive trophic levels is called energy flow.हिन्दी: सूर्य से उत्पादकों तथा फिर विभिन्न पोषण स्तरों से होकर ऊर्जा के स्थानांतरण को ऊर्जा प्रवाह कहते हैं।
15. 10% Law
10% Law – 10% नियम
English: Approximately 10% of the energy available at one trophic level is transferred to the next trophic level.हिन्दी: किसी पोषण स्तर पर उपलब्ध ऊर्जा का लगभग 10% ही अगले पोषण स्तर तक स्थानांतरित होता है।
16. Biodegradable Substance
Biodegradable – जैव निम्नीकरणीय
English: Substances that can be broken down by microorganisms through natural biological processes are called biodegradable substances.Examples: Vegetable waste, paper, leaves.
हिन्दी: सूक्ष्मजीवों द्वारा प्राकृतिक रूप से अपघटित होने वाले पदार्थ जैव निम्नीकरणीय पदार्थ कहलाते हैं।
17. Non-Biodegradable Substance
Non-Biodegradable – अजैव निम्नीकरणीय
English: Substances that are not easily broken down by natural biological processes are called non-biodegradable substances.Examples: Many plastics, certain pesticides and some synthetic materials.
हिन्दी: जो पदार्थ प्राकृतिक जैविक प्रक्रियाओं द्वारा आसानी से अपघटित नहीं होते, वे अजैव निम्नीकरणीय पदार्थ कहलाते हैं।
18. Biological Magnification
Biological Magnification – जैव आवर्धन
English: The increase in concentration of certain persistent pollutants at successive trophic levels is called biological magnification or biomagnification.हिन्दी: कुछ स्थायी प्रदूषकों की सांद्रता का उच्च पोषण स्तरों पर बढ़ते जाना जैव आवर्धन कहलाता है।
19. Ozone Layer
Ozone Layer – ओजोन परत
English: The ozone-rich region of the stratosphere that absorbs a significant portion of harmful ultraviolet radiation from the Sun.हिन्दी: समताप मंडल में ओजोन की अधिक मात्रा वाला क्षेत्र सूर्य की हानिकारक पराबैंगनी विकिरण का महत्वपूर्ण भाग अवशोषित करता है।
20. Ozone Depletion
Ozone Depletion – ओजोन क्षरण
English: The reduction in the concentration of stratospheric ozone is called ozone depletion.हिन्दी: समताप मंडल में ओजोन की मात्रा में कमी को ओजोन क्षरण कहते हैं।
21. Environmental Pollution
Pollution – प्रदूषण
English: Pollution is the undesirable change in the physical, chemical or biological characteristics of the environment that can cause harm to organisms and ecosystems.हिन्दी: पर्यावरण की भौतिक, रासायनिक या जैविक विशेषताओं में होने वाला अवांछनीय परिवर्तन, जो जीवों और पारितंत्र को नुकसान पहुँचा सकता है, प्रदूषण कहलाता है।
22. Ecosystem Balance
Ecological Balance – पारिस्थितिक संतुलन
English: A relatively stable condition in which organisms, populations and environmental factors interact within an ecosystem.हिन्दी: पारितंत्र में जीवों, उनकी जनसंख्याओं और पर्यावरणीय घटकों के बीच अपेक्षाकृत स्थिर पारस्परिक संबंध को पारिस्थितिक संतुलन कहा जाता है।
🔬 Key Concepts – Our Environment
1. Ecosystem Structure
☀️ Sunlight
→
🌱 Producers
→
🐇 Consumers
→
🦠 Decomposers
An ecosystem works through continuous interaction between biotic and abiotic components.
2. Trophic Levels
| Trophic Level | Main Organisms | Example |
|---|---|---|
| 1st | Producers | Grass, plants, algae |
| 2nd | Primary consumers | Deer, rabbit, grasshopper |
| 3rd | Secondary consumers | Frog, some fish |
| 4th | Higher consumers | Snake, eagle, hawk |
3. Food Chain Concept
🌱 Grass
Producer
Producer
→
🦗 Grasshopper
Primary Consumer
Primary Consumer
→
🐸 Frog
Secondary Consumer
Secondary Consumer
→
🐍 Snake
Higher Consumer
Higher Consumer
Remember: The arrow indicates the direction of transfer of food and energy.
4. Food Chain vs Food Web
| Food Chain | Food Web |
|---|---|
| Single feeding pathway. | Multiple interconnected feeding pathways. |
| Simple representation. | More complex representation. |
| Shows limited feeding relationships. | Shows several feeding relationships. |
5. Energy Flow
☀️ Sun
→
🌱 Producers
→
🐇 Herbivores
→
🦁 Carnivores
Energy flow is essentially unidirectional. Energy available at successive trophic levels generally decreases.
6. 10% Law
7. Biological Magnification
💧 Water
Low
Low
→
🌿 Plankton
Higher
Higher
→
🐟 Small Fish
Higher
Higher
→
🦅 Top Consumer
Highest
Highest
Persistent, non-biodegradable pollutants can become increasingly concentrated at higher trophic levels.
8. Decomposers and Nutrient Recycling
🍂 Dead Matter
→
🦠 Decomposers
→
🧪 Nutrients
→
🌱 Plants
9. Biodegradable vs Non-Biodegradable
| Biodegradable | Non-Biodegradable |
|---|---|
| Can generally be decomposed by microorganisms. | Not easily decomposed by natural biological processes. |
| Vegetable waste, leaves, paper. | Many plastics, some synthetic materials. |
| Usually less persistent in the environment. | May persist for long periods. |
10. Ozone Layer – Key Concept
The ozone layer is present mainly in the stratosphere. It absorbs a substantial portion of harmful UV radiation. Certain ozone-depleting substances can release reactive chlorine or bromine species that participate in ozone destruction.
Exam Point: Ozone depletion increases concern about exposure to harmful ultraviolet radiation.
11. Waste Management Concept
Reduce
→
Reuse
→
Recycle
→
Recover
→
Safe Disposal
Waste should preferably be prevented or reduced first, followed by reuse, recycling/recovery and environmentally safe disposal of unavoidable waste.
📝 30 MCQs – Definitions & Key Concepts
Multiple Choice Questions
📚 30 Important Questions with Answers
2 Marks Questions
2 Marks
1. Define environment.
Environment includes the living and non-living components surrounding an organism and their interactions.
2 Marks
2. What is an ecosystem?
An ecosystem is a functional unit where living organisms interact with one another and with non-living components.
2 Marks
3. Define biotic components.
The living components of an ecosystem, such as plants, animals, bacteria and fungi, are called biotic components.
2 Marks
4. Define abiotic components.
The non-living physical and chemical components such as air, water, soil, light and temperature are called abiotic components.
2 Marks
5. What is a producer?
A producer is an organism that prepares its own food, generally by photosynthesis.
2 Marks
6. What is a consumer?
A consumer is an organism that obtains food from other organisms.
3 Marks Questions
3 Marks
7. Define primary, secondary and tertiary consumers.
Primary consumers feed on producers. Secondary consumers generally feed on primary consumers. Tertiary or higher consumers occupy higher trophic positions and feed on organisms at lower consumer levels.
3 Marks
8. What are decomposers? Give examples.
Decomposers break down dead organic matter into simpler substances. Many bacteria and fungi act as decomposers.
3 Marks
9. Define food chain with an example.
A food chain is a sequence of organisms through which food and energy pass. Example: Grass → Grasshopper → Frog → Snake.
3 Marks
10. What is a food web?
A food web is a network of interconnected food chains showing multiple feeding relationships within an ecosystem.
3 Marks
11. What is a trophic level?
Each feeding position in a food chain is called a trophic level. Producers occupy the first trophic level.
4 Marks Questions
4 Marks
12. Explain the difference between biotic and abiotic components.
Biotic components are living components such as plants, animals and microorganisms. Abiotic components are non-living factors such as water, air, soil, temperature and sunlight.
4 Marks
13. Explain the role of producers in an ecosystem.
Producers capture solar energy and convert it into chemical energy. They form the first trophic level and provide food and energy to consumers.
4 Marks
14. Explain the role of decomposers.
Decomposers break down dead organisms and organic wastes, release nutrients into the environment and contribute to nutrient recycling.
4 Marks
15. Explain the 10% law.
Approximately 10% of the energy available at one trophic level is transferred to the next trophic level. The remaining energy is largely used in life processes and dissipated as heat.
5 Marks Questions
5 Marks
16. Explain food chain and food web with examples.
A food chain is a single feeding pathway, such as Grass → Deer → Tiger. A food web consists of several interconnected food chains and represents multiple feeding relationships.
5 Marks
17. Explain trophic levels with a suitable example.
In Grass → Grasshopper → Frog → Snake, grass is the producer and first trophic level; grasshopper is the primary consumer and second level; frog is the secondary consumer and third level; snake occupies a higher trophic position.
5 Marks
18. Explain energy flow in an ecosystem.
Energy enters mainly through sunlight, is captured by producers and then transferred through successive trophic levels. Available energy decreases at higher trophic levels.
5 Marks
19. What is biological magnification? Explain.
Biological magnification is the increase in concentration of certain persistent pollutants at successive trophic levels. Top consumers can therefore have the highest concentrations.
5 Marks
20. Differentiate biodegradable and non-biodegradable substances.
Biodegradable substances can generally be broken down by microorganisms, whereas non-biodegradable substances are not easily decomposed by natural biological processes and may persist for long periods.
6 Marks Questions
6 Marks
21. Explain the structure and components of an ecosystem.
An ecosystem consists of biotic and abiotic components. Biotic components include producers, consumers and decomposers. Abiotic components include sunlight, air, water, soil, temperature and minerals. These components interact continuously.
6 Marks
22. Explain the complete sequence of a food chain.
A typical sequence is Producer → Primary Consumer → Secondary Consumer → Higher Consumer. Example: Grass → Grasshopper → Frog → Snake → Eagle. Energy is transferred along the chain, with less available energy at successive levels.
6 Marks
23. Explain why energy flow is unidirectional.
Solar energy enters the ecosystem through producers and then passes to consumers. A considerable amount is dissipated as heat at each stage. Therefore, energy does not cycle back through the ecosystem in the same way nutrients do.
6 Marks
24. Explain the importance of decomposers in an ecosystem.
Decomposers break down dead organisms and wastes, release nutrients, support nutrient cycling, prevent accumulation of dead organic matter and make nutrients available to producers.
6 Marks
25. Explain biomagnification using a suitable food chain.
Water → Plankton → Small Fish → Large Fish → Fish-eating Bird. A persistent pollutant can become progressively concentrated at higher trophic levels. The top consumer may therefore receive the highest concentration.
Assertion–Reason
26. Assertion: Producers occupy the first trophic level.
Reason: Producers manufacture organic food using energy, generally from sunlight.
Reason: Producers manufacture organic food using energy, generally from sunlight.
Answer: Both Assertion and Reason are true, and Reason correctly explains the Assertion.
27. Assertion: Energy decreases at successive trophic levels.
Reason: Much energy is used in life processes and dissipated as heat.
Reason: Much energy is used in life processes and dissipated as heat.
Answer: Both Assertion and Reason are true, and Reason correctly explains the Assertion.
28. Assertion: Food webs contain several interconnected food chains.
Reason: Organisms may have more than one feeding relationship.
Reason: Organisms may have more than one feeding relationship.
Answer: Both Assertion and Reason are true, and Reason correctly explains the Assertion.
HOTS / Application-Based Questions
29. Why would the disappearance of producers seriously affect an ecosystem?
Producers form the first trophic level and provide the main entry of energy into most ecosystems. Their disappearance would reduce food and energy available to consumers and disrupt the entire food web.
30. Why can persistent pollutants become a greater concern at higher trophic levels?
Some persistent pollutants are not easily broken down or eliminated. They can accumulate in organisms and become increasingly concentrated as organisms at higher trophic levels consume contaminated organisms from lower levels.
⚡ Quick Revision – Important Definitions
One-Minute Revision
Environment
Living + non-living surroundings and interactions.
Ecosystem
Biotic + abiotic components interacting.
Producer
Makes its own food.
Consumer
Obtains food from other organisms.
Decomposer
Breaks down dead organic matter.
Food Chain
Single feeding pathway.
Food Web
Interconnected food chains.
Trophic Level
Feeding position in a food chain.
Energy Flow
Mainly unidirectional.
10% Law
Approx. 10% energy transfer.
Biomagnification
Increase of certain persistent pollutants at higher trophic levels.
Biodegradable
Can generally be biologically decomposed.
Non-Biodegradable
Not easily biologically decomposed.
Ozone Layer
Absorbs much harmful UV radiation.
Most Important Exam Keywords
| Term | Must Remember |
|---|---|
| Ecosystem | Biotic + Abiotic |
| Producer | First trophic level |
| Primary Consumer | Feeds on producer |
| Secondary Consumer | Feeds on primary consumer |
| Decomposer | Breaks down dead matter |
| Food Chain | Single feeding pathway |
| Food Web | Interconnected food chains |
| Trophic Level | Position in food chain |
| 10% Law | Approx. 10% transfer |
| Biomagnification | Higher pollutant concentration at higher trophic levels |
| Biodegradable | Decomposed biologically |
| Non-Biodegradable | Persists / not easily decomposed |
| Ozone Layer | Protection from much UV radiation |
Important Sequences
Energy Flow:
☀️ Sun → 🌱 Producers → 🐇 Primary Consumers → 🐸 Secondary Consumers → 🦅 Higher Consumers
☀️ Sun → 🌱 Producers → 🐇 Primary Consumers → 🐸 Secondary Consumers → 🦅 Higher Consumers
Decomposition:
🍂 Dead Organic Matter → 🦠 Decomposers → 🧪 Nutrients → 🌱 Producers
🍂 Dead Organic Matter → 🦠 Decomposers → 🧪 Nutrients → 🌱 Producers
Biomagnification:
💧 Water → 🌿 Plankton → 🐟 Small Fish → 🐟 Large Fish → 🦅 Top Consumer
💧 Water → 🌿 Plankton → 🐟 Small Fish → 🐟 Large Fish → 🦅 Top Consumer
Board Exam Tips
1. Definition questions में key scientific words जरूर लिखें।
2. Food chain में arrows की direction सही रखें।
3. Producer को first trophic level याद रखें।
4. Decomposer का मुख्य कार्य nutrient recycling से जोड़ें।
5. 10% law में “approximately” या “लगभग” लिखना उचित है।
6. Biomagnification को persistent/non-biodegradable pollutants से जोड़कर समझें।
7. Ozone layer को stratosphere और UV radiation से जोड़कर याद रखें।
2. Food chain में arrows की direction सही रखें।
3. Producer को first trophic level याद रखें।
4. Decomposer का मुख्य कार्य nutrient recycling से जोड़ें।
5. 10% law में “approximately” या “लगभग” लिखना उचित है।
6. Biomagnification को persistent/non-biodegradable pollutants से जोड़कर समझें।
7. Ozone layer को stratosphere और UV radiation से जोड़कर याद रखें।
Final Summary
Our Environment chapter में ecosystem, biotic and abiotic components, producers, consumers, decomposers, food chains, food webs, trophic levels, energy flow, 10% law, biological magnification, biodegradable and non-biodegradable substances तथा ozone layer जैसे concepts अत्यंत महत्वपूर्ण हैं। Board examination में इनकी definitions, examples, diagrams, food chains, differences और application-based questions विशेष रूप से उपयोगी हैं।
Class 10 Science | Chapter – Our Environment
Important Definitions • Key Concepts • Food Chain • Energy Flow • Biomagnification
Important Definitions • Key Concepts • Food Chain • Energy Flow • Biomagnification
