Class 10th Science Chapter 13 – Our Environment | Important Diagrams and Food Chains

Our Environment | Important Diagrams and Food Chains

Class 10 Science | Chapter – Our Environment | Important Exam-Oriented Concepts

🌿 Important Diagrams and Food Chains

1. Ecosystem – Ecosystem Diagram

English: An ecosystem consists of living organisms (biotic components) interacting with non-living factors (abiotic components) such as air, water, soil, light and temperature.

हिन्दी: पारितंत्र (Ecosystem) में जैविक घटक और अजैविक घटक एक-दूसरे के साथ परस्पर क्रिया करते हैं।

Exam Point: Ecosystem = Biotic components + Abiotic components.

2. Basic Food Chain Diagram

A food chain represents the transfer of food and energy from one organism to another. Food → Energy → Next Trophic Level

☀️ Sun
सूर्य

→

🌱 Grass
Producer

→

🐇 Rabbit
Primary Consumer

→

🦊 Fox
Secondary Consumer

→

🦠 Decomposers

Important: In a food chain, the arrow generally represents the direction of transfer of food/energy from the organism being eaten to the organism that eats it.

3. Food Chain – Trophic Levels

1st Trophic Level
🌱 Producers

→

2nd Trophic Level
🐛 Primary Consumers

→

3rd Trophic Level
🐸 Secondary Consumers

→

4th Trophic Level
🦅 Tertiary Consumers

Trophic Level	Organism	Example
1st	Producer	Grass, algae, plants
2nd	Primary consumer	Grasshopper, deer, rabbit
3rd	Secondary consumer	Frog, snake
4th	Tertiary consumer	Eagle, hawk

4. Important Food Chain Examples

Food Chain – 1

🌱 Grass

→

🐇 Rabbit

→

🦊 Fox

Food Chain – 2

🌱 Grass

→

🦗 Grasshopper

→

🐸 Frog

→

🐍 Snake

→

🦅 Eagle

Food Chain – 3

🌿 Plants

→

🐛 Caterpillar

→

🐦 Bird

→

🦅 Hawk

Food Chain – 4: Aquatic Ecosystem

🌿 Phytoplankton

→

🦐 Zooplankton

→

🐟 Small Fish

→

🐠 Large Fish

→

🦅 Fish-eating Bird

5. Food Web – Important Diagram

Food Web: Many interconnected food chains form a food web. A food web provides multiple feeding relationships within an ecosystem.

6. Energy Flow in an Ecosystem

Energy enters an ecosystem mainly through sunlight. Producers convert solar energy into chemical energy by photosynthesis. Energy then passes through different trophic levels.

☀️ Solar Energy

→

🌱 Producers

→

🐇 Herbivores

→

🦊 Carnivores

→

🦅 Higher Consumers

10% Law: Approximately 10% of the energy available at one trophic level is transferred to the next trophic level. A large part is used in life processes and lost as heat.

7. Energy Pyramid

Energy decreases as we move from producers towards higher trophic levels.

8. Biomagnification Diagram

Biomagnification means the concentration of certain persistent, non-biodegradable pollutants increases at successive trophic levels.

💧 Water
Low pollutant

→

🌿 Plankton
More

→

🐟 Small Fish
Higher

→

🐟 Large Fish
Very High

→

🦅 Top Consumer
Highest

Exam Rule: Biomagnification is especially significant for persistent pollutants that are not readily broken down or excreted.

9. Decomposer Cycle – Nutrient Recycling

Decomposers break down dead plants, animals and organic wastes. Nutrients are returned to the environment and can again be used by producers.

🌿 Dead Organic Matter

→

🦠 Decomposers

→

🧪 Nutrients in Soil

→

🌱 Producers

10. Important Diagram Labels for Board Exam

Diagram	Labels You Should Remember
Ecosystem	Biotic, Abiotic, Producers, Consumers, Decomposers
Food Chain	Producer → Primary Consumer → Secondary Consumer → Tertiary Consumer
Food Web	Multiple interconnected food chains
Energy Flow	Sun → Producers → Consumers
Energy Pyramid	Producers at base; higher consumers towards top
Biomagnification	Pollutant concentration increases at higher trophic levels
Decomposition	Dead matter → Decomposers → Nutrients → Producers

11. Important Definitions

Food Chain: A sequence of organisms through which food and energy pass.

Food Web: A network of interconnected food chains.

Trophic Level: Each step or position in a food chain is called a trophic level.

Producer: An organism that prepares its own food, generally through photosynthesis.

Consumer: An organism that obtains food from other organisms.

Decomposer: Organisms such as many bacteria and fungi that break down dead organic matter.

Biomagnification: Increase in concentration of certain persistent pollutants at successive trophic levels.

📝 30 MCQs – Important Diagrams & Food Chains

MCQ Practice

📚 30 Important Questions with Answers

2 Marks Questions

2 Marks 1. What is a food chain?

A food chain is a sequence of organisms through which food and energy are transferred from one organism to another.

2 Marks 2. What is a trophic level?

Each step or position occupied by an organism in a food chain is called a trophic level.

2 Marks 3. Define food web.

A food web is a network of interconnected food chains in an ecosystem.

2 Marks 4. What are producers?

Producers are organisms that manufacture their own food, generally by photosynthesis. Green plants and algae are common examples.

2 Marks 5. What are decomposers?

Decomposers break down dead organic matter and help return nutrients to the environment. Many bacteria and fungi act as decomposers.

2 Marks 6. State the 10% law.

Approximately 10% of the energy available at one trophic level is transferred to the next trophic level.

3 Marks Questions

3 Marks 7. Differentiate between food chain and food web.

Food chain represents a single feeding pathway, whereas a food web consists of many interconnected feeding pathways. Food webs generally represent feeding relationships more realistically.

3 Marks 8. Explain the different trophic levels.

1. Producers form the first trophic level.
2. Herbivores/primary consumers form the second level.
3. Secondary and tertiary consumers occupy higher levels.

3 Marks 9. Write three functions of decomposers.

They decompose dead organisms, recycle nutrients and help maintain soil fertility and ecosystem nutrient cycles.

3 Marks 10. Why is energy flow called unidirectional?

Energy enters mainly from the Sun, passes through producers and consumers, and a significant portion is dissipated as heat. It does not return to the Sun through the ecosystem.

3 Marks 11. Construct a food chain containing four trophic positions.

Grass → Grasshopper → Frog → Snake.
Grass = producer; Grasshopper = primary consumer; Frog = secondary consumer; Snake = higher consumer.

4 Marks Questions

4 Marks 12. Explain the role of producers in an ecosystem.

Producers capture solar energy through photosynthesis and convert it into chemical energy. They form the first trophic level and provide food and energy to consumers. They also release oxygen during photosynthesis.

4 Marks 13. Explain energy transfer through trophic levels.

Energy flows from producers to primary consumers and then to higher consumers. Only a small fraction, approximately 10%, is transferred to the next trophic level. Much energy is used in metabolism and dissipated as heat.

4 Marks 14. Explain biomagnification with a food-chain example.

Persistent pollutants can accumulate in organisms and become increasingly concentrated at higher trophic levels. Example: Water → Plankton → Small fish → Large fish → Fish-eating bird.

4 Marks 15. Draw and explain an energy pyramid.

The broad base represents producers. Above them are primary consumers, secondary consumers and higher consumers. Available energy generally decreases towards the top.

5 Marks Questions

5 Marks 16. Draw a food web and explain its significance.

A food web consists of several interconnected food chains. It demonstrates that organisms may have more than one food source and may be prey for several organisms. Therefore, it provides a more realistic representation of feeding relationships in an ecosystem.

5 Marks 17. Explain the importance of decomposers in maintaining ecosystem balance.

Decomposers break down dead organisms and wastes, release nutrients into soil and water, contribute to nutrient cycling and prevent accumulation of dead organic matter. Producers can reuse these nutrients.

5 Marks 18. Explain the 10% law using an example.

If producers contain 10,000 units of available energy, approximately 1,000 units may pass to primary consumers, about 100 units to secondary consumers and about 10 units to the next trophic level. The values are illustrative of the approximate 10% transfer principle.

5 Marks 19. Explain the relationship between food chain, trophic level and energy flow.

A food chain describes feeding relationships. Each organism's position represents a trophic level. Energy enters through producers and passes from one trophic level to another, decreasing substantially at successive levels.

5 Marks 20. Explain biomagnification and why top consumers may be most affected.

Persistent pollutants may accumulate in organisms and become more concentrated at successive trophic levels. Since top consumers feed on organisms from lower trophic levels, pollutant concentration can become highest in them.

6 Marks Questions

6 Marks 21. Draw and explain an ecosystem diagram.

An ecosystem has biotic components such as producers, consumers and decomposers, and abiotic components such as sunlight, air, water, soil and temperature. These components interact and together form a functioning ecosystem.

6 Marks 22. Explain food chain with suitable examples and trophic levels.

Example: Grass → Grasshopper → Frog → Snake → Eagle. Grass is the producer; grasshopper is the primary consumer; frog is a secondary consumer; snake and eagle occupy higher trophic positions. Energy decreases at successive levels.

6 Marks 23. Explain food web with a suitable diagram.

A food web is formed when different food chains intersect. For example, plants may be eaten by rabbit, grasshopper and mouse; these organisms may be eaten by different predators. Such interconnections form a food web.

6 Marks 24. Explain energy flow in an ecosystem and the 10% law.

Solar energy is captured by producers and transferred through consumers. Approximately 10% of energy at one trophic level is transferred to the next. Much energy is used in life processes and lost as heat. Therefore, available energy decreases at higher trophic levels.

6 Marks 25. Explain biomagnification using a diagram.

Water → Plankton → Small fish → Large fish → Fish-eating bird. If a persistent pollutant enters the water, its concentration can increase through successive trophic levels, becoming greatest in the top consumer.

Assertion–Reason

26. Assertion (A): Producers occupy the first trophic level.
Reason (R): Producers convert solar energy into chemical energy.

Answer: Both A and R are true, and R correctly explains A.

27. Assertion (A): Energy decreases at successive trophic levels.
Reason (R): A large portion of energy is used in life processes and dissipated as heat.

Answer: Both A and R are true, and R correctly explains A.

28. Assertion (A): Food web contains several interconnected food chains.
Reason (R): Organisms can have more than one feeding relationship.

Answer: Both A and R are true, and R correctly explains A.

HOTS / Application-Based Questions

29. If all producers disappeared from an ecosystem, what would happen?

The primary source of food and energy for consumers would be lost. Consumers would decline, followed by higher trophic levels. The ecosystem's energy flow and food chains would be severely disrupted.

30. Why can removal of one species affect many organisms in a food web?

Because a food web contains interconnected feeding relationships. Removing one species can reduce food availability for some organisms and increase the population of organisms that were previously controlled by it.

⚡ Quick Revision – Our Environment

One-Minute Revision

Ecosystem Biotic + Abiotic components Food Chain Single feeding pathway Food Web Interconnected food chains Producer 1st trophic level Primary Consumer 2nd trophic level Secondary Consumer 3rd trophic level Decomposer Recycles nutrients 10% Law Approx. 10% energy transfer Biomagnification Pollutant concentration increases at higher trophic levels

Most Important Food Chains

🌱 Grass → 🐇 Rabbit → 🦊 Fox

🌱 Grass → 🦗 Grasshopper → 🐸 Frog → 🐍 Snake → 🦅 Eagle

🌿 Plants → 🐛 Caterpillar → 🐦 Bird → 🦅 Hawk

🌊 Phytoplankton → 🦐 Zooplankton → 🐟 Small Fish → 🐟 Large Fish → 🦅 Fish-eating Bird

Board Exam Diagram Checklist

Must Remember	Key Point
Food Chain	Producer → Consumers
Trophic Level	Each feeding position
Food Web	Interconnected food chains
Energy Flow	Unidirectional
10% Law	Approx. 10% transfer
Energy Pyramid	Producers at base
Biomagnification	Higher concentration at higher trophic levels
Decomposers	Nutrient recycling

⭐ Board Exam Tip: जब food chain या food web बनाएं, तो arrows की direction स्पष्ट रखें और हर trophic level को सही नाम से label करें। Diagram के साथ 2–3 explanatory points लिखने से answer अधिक complete बनता है।

Final Summary

Environment में organisms एक-दूसरे से feeding relationships के माध्यम से जुड़े रहते हैं। Food chain energy transfer का एक मार्ग दिखाती है, जबकि food web अनेक interconnected food chains को दर्शाता है। Producers पहला trophic level बनाते हैं और consumers उनके बाद आते हैं। Decomposers dead organic matter को तोड़कर nutrients को ecosystem में वापस लाते हैं। प्रत्येक trophic level पर उपलब्ध energy घटती जाती है और लगभग 10% energy अगले trophic level तक पहुँचती है। Persistent pollutants का concentration higher trophic levels पर बढ़ सकता है, जिसे biomagnification कहते हैं।

Class 10 Science | Our Environment
Important Diagrams • Food Chains • Food Web • Energy Flow • Trophic Levels