🌟 Class 8 Science – Curiosity Chapter 13
🌍 Our Home: Earth, a Unique Life Sustaining Planet
🟢 1. What is one major reason Mars cannot currently support life like Earth?
(i) It has too many volcanoes.
(ii) It is too close to the Sun.
(iii) It lacks a thick atmosphere and liquid water.
(iv) Its magnetic field is too strong.
✅ Answer:
👉 (iii) It lacks a thick atmosphere and liquid water
🧠 Explanation:
- Mars has a very thin atmosphere
- Cannot trap heat 🌡️
- No stable liquid water 💧
📌 These conditions make life impossible ✔️
🟢 Class 8 Science Curiosity Chapter 13 Question 2, 3 and 4
🟢 2. Which of these is an example of geodiversity?
(i) Variety of bird chirping in a forest.
(ii) Different landforms like mountains, valleys, and deserts.
(iii) Changing weather during monsoons.
(iv) Number of different types of fish in a pond.
✅ Answer:
👉 (ii) Different landforms like mountains, valleys, and deserts
🧠 Explanation:
- Geodiversity = non-living features
- Includes rocks, soil, landforms 🪨
🟢 3. If the Earth were smaller with the same density, what might happen to its atmosphere?
(i) It would become thicker and hotter.
(ii) It would escape into space due to weaker gravity.
(iii) It would become frozen.
(iv) It would cause stronger winds.
✅ Answer:
👉 (ii) It would escape into space due to weaker gravity
🧠 Explanation:
- Smaller size → weaker gravity
- Cannot hold gases 🌬️
- Atmosphere escapes into space
🟢 4. In sexual reproduction, why are offspring different from their parents?
(i) They grow in different climates.
(ii) They eat different food.
(iii) They acquire new instructions after birth.
(iv) They get mixed instructions (genes) from both parents.
✅ Answer:
👉 (iv) They get mixed instructions (genes) from both parents
🧠 Explanation:
- Genes from both parents combine 🧬
- Creates variation (भिन्नता)
🟢 Question 5 and 6 of Class 8 Science Curiosity Chapter 13
🟢 5. You notice tiny green plants growing in cracks on your school wall after the monsoon. Where do you think the seeds came from? What conditions helped these plants grow there?
✅ Answer:
🌱 Source of seeds:
- 🌬️ Carried by wind
- 🐦 Dropped by birds
🌧️ Favourable conditions:
- Moisture from rain 💧
- Dust/soil in cracks 🌱
- Sunlight ☀️
- Air 🌬️
📌 Conclusion:
👉 Life can grow even in harsh conditions ✔️
🟢 6. A city has recently cut down a large patch of forest to build new roads and buildings. Discuss the possible effects this could have on the local climate and biodiversity? How might this affect water availability or quality in the area?
✅ Answer:
🌡️ Effects on Climate:
- Temperature increases 🔥
- Rainfall decreases 🌧️
🐾 Effects on Biodiversity:
- Loss of habitat 🏚️
- Animals migrate or die ❌
- Biodiversity decreases 📉
💧 Effects on Water:
- Less groundwater recharge ⬇️
- Soil erosion 🌊
- Water pollution increases ⚠️
📌 Conclusion:
👉 Deforestation disturbs entire ecosystem balance
🟢 Class 8 Science Curiosity Chapter 13 Question 7, 8 and 9
🟢 7. A friend says, “The Earth has always had climate changes in the past, so today’s global warming is nothing new.” How would you respond?
✅ Answer:
🧠 Response:
✔️ Climate change happened before
❗ But today’s change is different because:
- ⚡ Much faster
- 👨🏭 Caused by human activities
🌫️ Burning fossil fuels → CO₂ increase
👉 Heat gets trapped → global warming
📌 Conclusion:
👉 Current climate change is human-driven & dangerous
🟢 8. Imagine Earth’s magnetic field suddenly disappeared. What kinds of problems could arise for life on Earth?
✅ Answer:
🛡️ Magnetic field = protective shield
❌ Without it:
- ☀️ Solar wind damages atmosphere
- 🌌 Harmful radiation reaches Earth
- 🧬 Cells get damaged
📌 Conclusion:
👉 Life would become very difficult to survive
🟢 9. You are tasked with designing a new settlement for humans on Mars. Name three things you would need to recreate from Earth. Which is hardest?
✅ Answer:
🌍 Needed:
1. 🌬️ Breathable atmosphere
2. 💧 Liquid water
3. 🌱 Food system
⚠️ Hardest:
👉 Atmosphere
🧠 Reason:
- Requires planet-level change
- Very complex & large-scale
📌 Conclusion:
👉 Atmosphere is hardest to replicate
🟢 Class 8 Science Curiosity Chapter 13 Question 10, 11 and 12
🟢 10. In a village, temperature is increasing and rainfall is unpredictable. What could be causing this? Suggest two solutions.
✅ Answer:
🌡️ Causes:
- Global warming 🌍
- Deforestation 🌳❌
🌱 Solutions:
1. 💧 Rainwater harvesting
2. 🌳 Tree plantation (Afforestation)
📌 Conclusion:
👉 Adaptation is necessary ✔️
🟢 11. If there were no atmosphere on the Earth, would it affect life, temperature and water?
✅ Answer:
❌ Effect on Life:
- No oxygen 🫁
- No protection from UV rays ☀️
🌡️ Effect on Temperature:
💧 Effect on Water:
- No liquid water
- Either freeze or evaporate
📌 Conclusion:
👉 Atmosphere is essential for life ✔️
🟢 12. Discuss five examples of vegetative propagation.
✅ Answer:
🌱 Examples:
1. 🥔 Potato → from eyes
2. 🌿 Ginger → rhizome
3. 🪴 Money plant → stem cutting
4. 🌾 Sugarcane → stem (setts)
5. 🌹 Rose → stem cutting
📌 Conclusion:
👉 Plants can grow without seeds ✔️
