Health, Nature's Harmony, Earth & Cells: Class 8–9 Science Essentials: 30 flashcards
All 30 flashcards from this kit, free and with no sign-up.
1. What is the definition of health?
Show the answer
A state of complete physical, mental, and social well-being — not just the absence of disease.
2. Why is health called a 'treasure'?
Show the answer
Because it must be actively protected through good habits, not taken for granted until it is lost.
3. How does nature maintain balance?
Show the answer
Through cycles and interdependence — plants, animals, and decomposers each play a role and nothing is wasted.
4. What happens when one part of nature's web is disturbed?
Show the answer
The effects ripple outward and affect the whole system, including human health.
5. Why is Earth the only known life-sustaining planet?
Show the answer
It has liquid water, a protective atmosphere, moderate temperature, and diverse habitats — all together.
6. What is the basic unit of life?
Show the answer
The cell.
7. What is a tissue?
Show the answer
A group of similar cells that work together to perform a function.
8. What is an organ?
Show the answer
A structure made of different tissues working together (e.g., heart, stomach).
9. What is an organ system?
Show the answer
A group of organs that work together to perform a major function (e.g., digestive system).
10. List the levels of organisation in living things from smallest to largest.
Show the answer
Cell → tissue → organ → organ system → organism.
11. Name three plant tissues.
Show the answer
Xylem, phloem, and parenchyma.
12. Name three animal tissues.
Show the answer
Epithelial, muscle, and nervous tissues.
13. Why does the stomach not digest itself?
Show the answer
A layer of mucus continuously protects the stomach lining from acid.
14. What is the role of the digestive system?
Show the answer
It breaks food into simpler molecules that can be absorbed into the blood.
15. What is respiration?
Show the answer
The process that releases energy from food molecules inside cells.
16. What does a balanced diet provide?
Show the answer
Carbohydrates, proteins, fats, vitamins, and minerals.
17. How are environmental health and human health connected?
Show the answer
Pollution, deforestation, and resource overuse harm nature and people — protecting nature protects ourselves.
18. Why do cells divide?
Show the answer
To repair damaged tissues and to help the body grow.
19. Why is mental and social well-being important for health?
Show the answer
A person who is physically fit but anxious or isolated is not fully healthy.
20. What makes an ecosystem truly healthy?
Show the answer
Diversity of organisms — not just trees, but insects, birds, and decomposers too.
21. Give two small actions that help restore harmony in nature.
Show the answer
Reducing waste and planting trees.
22. How does studying cells and tissues explain growth and repair?
Show the answer
Cells divide to heal wounds and help tissues grow; understanding this explains how the body maintains itself.
23. Compare plant and animal tissues in terms of growth.
Show the answer
Plant tissues continue growing throughout life; animal tissues mostly stop growing after maturity.
24. What provides structural support in plant cells versus animal bodies?
Show the answer
Rigid cell walls support plants; skeleton and muscles support animals.
25. Why does a person who eats enough still starve if digestion fails?
Show the answer
Because food must be broken down and absorbed for cells to get energy — eating alone is not enough.
26. What is the big-picture connection between the four topics?
Show the answer
Health depends on a healthy environment, which depends on Earth's unique conditions, which support life built from cells and tissues.
27. What happens if the mucus barrier in the stomach fails?
Show the answer
Ulcers can form because acid damages the unprotected stomach lining.
28. Why is Earth's distance from the Sun important for life?
Show the answer
It helps keep temperatures moderate — not too hot like Venus, not too cold like Mars.
29. What role do decomposers play in nature's harmony?
Show the answer
They return nutrients to the soil, completing cycles so nothing is wasted.
30. How does exercise show that tissues adapt?
Show the answer
Muscle tissue changes and strengthens with regular use — tissues respond to what the body does.
Your notes can be a kit like these
Every kit here was made from real study material. Point Veda at a chapter, a PDF, a photo or a link and get notes, flashcards, practice MCQs, games and a scored test — free, in 42 languages.
- Chapter notes
- Flashcards
- Practice MCQs
- Scored tests
- Exam prep
Get Veda free See what students get
Free to start · No ads · Works in 42 languages