Class 8 Science
Complete Revision Guide • Units 1–12
Original Educational Study Material
Designed for revision, practice, and exam preparation
Copyright © 2026 Hassan
This independently created guide is not affiliated with, sponsored by, or endorsed by any textbook publisher
or educational company.
Class 8 Science • Complete Revision Guide • © 2026 Hassan
,Contents
1. Unit 1: Ecology
2. Unit 2: Human Nervous System
3. Unit 3: Variations, Heredity and Cell Division
4. Unit 4: Biotechnology
5. Unit 5: Periodic Table
6. Unit 6: Chemical Reactions
7. Unit 7: Acids, Bases and Salts
8. Unit 8: Force and Pressure
9. Unit 9: Reflection and Refraction of Light
10. Unit 10: Electricity and Magnetism
11. Unit 11: The Universe
12. Unit 12: Technology in Everyday Life
13. Final Glossary
14. Complete Revision Test
15. Answer Key
Class 8 Science • Complete Revision Guide • © 2026 Hassan
, Unit 1: Ecology
Simple Concept Explanation
Ecology is the study of how living organisms interact with one another and with their surroundings. An
ecosystem contains living components such as plants, animals and microorganisms, and non-living
components such as air, water, soil, light and temperature. Energy usually enters an ecosystem through
sunlight, passes to producers and then to consumers.
Key Terms
Ecosystem: A community of organisms interacting with their physical environment.
Producer: An organism, usually a green plant, that makes its own food.
Consumer: An organism that obtains food by eating other organisms.
Decomposer: An organism such as a bacterium or fungus that breaks down dead material.
Food chain: A sequence showing how food and energy pass from one organism to another.
Original Examples
Grass → grasshopper → frog is an example of a simple food chain.
A pond contains water, algae, fish, microorganisms and many non-living factors.
Decomposers return useful substances to the environment.
Short Questions
1. What is an ecosystem?
2. Differentiate between producers and consumers.
3. Why are decomposers important?
4. What is a food chain?
Original MCQs
1. Which is a producer?
A. Lion
B. Grass
C. Frog
D. Eagle
2. Which is non-living?
A. Bacteria
B. Tree
C. Water
Class 8 Science • Complete Revision Guide • © 2026 Hassan
Complete Revision Guide • Units 1–12
Original Educational Study Material
Designed for revision, practice, and exam preparation
Copyright © 2026 Hassan
This independently created guide is not affiliated with, sponsored by, or endorsed by any textbook publisher
or educational company.
Class 8 Science • Complete Revision Guide • © 2026 Hassan
,Contents
1. Unit 1: Ecology
2. Unit 2: Human Nervous System
3. Unit 3: Variations, Heredity and Cell Division
4. Unit 4: Biotechnology
5. Unit 5: Periodic Table
6. Unit 6: Chemical Reactions
7. Unit 7: Acids, Bases and Salts
8. Unit 8: Force and Pressure
9. Unit 9: Reflection and Refraction of Light
10. Unit 10: Electricity and Magnetism
11. Unit 11: The Universe
12. Unit 12: Technology in Everyday Life
13. Final Glossary
14. Complete Revision Test
15. Answer Key
Class 8 Science • Complete Revision Guide • © 2026 Hassan
, Unit 1: Ecology
Simple Concept Explanation
Ecology is the study of how living organisms interact with one another and with their surroundings. An
ecosystem contains living components such as plants, animals and microorganisms, and non-living
components such as air, water, soil, light and temperature. Energy usually enters an ecosystem through
sunlight, passes to producers and then to consumers.
Key Terms
Ecosystem: A community of organisms interacting with their physical environment.
Producer: An organism, usually a green plant, that makes its own food.
Consumer: An organism that obtains food by eating other organisms.
Decomposer: An organism such as a bacterium or fungus that breaks down dead material.
Food chain: A sequence showing how food and energy pass from one organism to another.
Original Examples
Grass → grasshopper → frog is an example of a simple food chain.
A pond contains water, algae, fish, microorganisms and many non-living factors.
Decomposers return useful substances to the environment.
Short Questions
1. What is an ecosystem?
2. Differentiate between producers and consumers.
3. Why are decomposers important?
4. What is a food chain?
Original MCQs
1. Which is a producer?
A. Lion
B. Grass
C. Frog
D. Eagle
2. Which is non-living?
A. Bacteria
B. Tree
C. Water
Class 8 Science • Complete Revision Guide • © 2026 Hassan
