Complete Solutions and Summary of Our Home: Earth, a Unique Life Sustaining Planet – Curiosity Class 8 Science Chapter 13 – Summary, Questions, Answers, Extra Questions
Detailed summary, explanations, question answers, and extra solved questions for Curiosity Class VIII Science Chapter 13 ‘Our Home: Earth, a Unique Life Sustaining Planet’
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Our Home: Earth, a Unique Life Sustaining Planet
Chapter 13: Curiosity Textbook of Science for Grade 8
Complete Study Guide with Interactive Learning
Chapter Overview
What You'll Learn
Earth's Uniqueness
Explore why Earth is the only known planet supporting life, including its thin crust and habitable conditions.
Solar System Planets
Compare Earth's features with other planets like Venus and Mars.
Factors for Life
Understand position, size, atmosphere, and magnetic field enabling life.
Sustaining Life
Learn about air, water, soil, and reproduction in maintaining Earth's biosphere.
Key Topics Summary
This chapter synthesizes concepts from previous grades to explain Earth's uniqueness as a life-sustaining planet. It covers the solar system, greenhouse effect, habitable zone, and threats like climate change.
Key Highlights
Earth's distance from the Sun allows liquid water; its atmosphere traps heat via greenhouse effect; magnetic field protects from solar wind; reproduction ensures continuity; threats include pollution and biodiversity loss.
Comprehensive Chapter Summary
1. Introduction to Earth's Uniqueness
The chapter concludes the middle stage science journey by exploring why Earth stands out in the universe. It orbits the Sun, sustains diverse life, and features vast landscapes. Satellite images, like ISRO's false-color mosaic, help study Earth's surface, plants, oceans, temperature, and environmental issues. Definition: False-color image - Uses different colors to represent information beyond visible light.
2. Why Is Earth a Unique Planet?
Life on Earth's Surface
All life exists on Earth's thin crust, comparable to an apple's skin. This layer supports mountains, rivers, forests, and humans. Activity 13.1 encourages listing features like gravity holding air and enabling blood circulation. Earth provides air, water, soil, rocks, and timber essential for life. Definition: Crust - Earth's outermost layer where life thrives.
Key Benefits for Life
Earth's features sustain life despite changes; it's the only known planet with diverse life forms. Definition: Biosphere - Zone including land, water, and air where life interacts.
Comparison to Other Planets
Billions of planets exist, but Earth uniquely supports life. Activity 13.2 involves researching planetary temperatures, sizes, and atmospheres. Definition: Atmosphere - Layer of gases surrounding a planet.
3. Planets of the Solar System
Venus and Greenhouse Effect
Venus is hottest due to carbon dioxide trapping heat (greenhouse effect). Earth has a mild version maintaining suitable temperatures. Definition: Greenhouse Effect - Trapping of heat by atmospheric gases like CO2.
Habitable Zone
Earth's position allows liquid water; called Goldilocks zone. Mars might have had life in the past. Definition: Habitable Zone - Distance from a star where liquid water can exist.
Earth's Size and Atmosphere
Right size for gravity to hold atmosphere; ozone blocks UV rays. Definition: Ozone Layer - Atmospheric part shielding from harmful UV radiation.
4. Earth's Magnetic Field
Protection Role
Acts as shield against cosmic rays and solar wind, preserving atmosphere and life. Definition: Magnetic Field - Region around Earth influenced by its magnetism, originating from molten iron core.
5. Sustaining Life on Earth
Interconnected Systems
Atmosphere, hydrosphere, geosphere, and biosphere interact. Photosynthesis, water cycle, nutrient recycling maintain balance. Definition: Hydrosphere - All water on Earth; Geosphere - Solid parts like rocks and soil.
Geodiversity and Balance
Variety in landforms creates habitats; balance prevents disruptions. Definition: Geodiversity - Variety in rocks, soils, landforms, and processes shaping Earth.
6. Reproduction and Continuity
Ensures life persists; asexual (exact copies) and sexual (variations). Definition: Asexual Reproduction - Single parent produces identical offspring; Sexual Reproduction - Two parents combine gametes for varied offspring. Examples: Vegetative propagation in plants; fertilization in animals.
7. Threats to Life
Triple planetary crisis: Climate change (global warming from greenhouse gases), biodiversity loss, pollution. Definition: Climate Change - Long-term shifts in temperature and weather due to human actions like burning fossil fuels.
Key Concepts and Definitions
Habitable Zone
Range of distances from the Sun where water remains liquid; also called Goldilocks zone.
Greenhouse Effect
Trapping of heat by atmospheric gases like carbon dioxide, maintaining Earth's temperature.
Ozone Layer
Atmospheric shield blocking harmful UV rays from the Sun.
Magnetic Field
Protective shield deflecting harmful particles like solar wind and cosmic rays.
Biosphere
All living beings and their environments on Earth.
Asexual Reproduction
Single parent produces identical offspring, e.g., vegetative propagation.
Important Facts and Figures
Questions and Answers from Chapter
Short Questions
Q1. What is one major reason Mars cannot currently support life like Earth?
Q2. Which of these is an example of geodiversity?
Q3. If the Earth were smaller with the same density, what might happen to its atmosphere?
Q4. In sexual reproduction, why are offspring different from their parents?
Q5. What do you think Earth would look like if there were no life on it at all?
Q6. Why don’t dogs lay eggs? Or hens give birth to live chicks?
Q7. If a spaceship carried soil and water to Mars, could plants start growing there?
Q8. What is the temperature or distance from the Sun, the only factor that makes the Earth habitable?
Q9. What would happen if the size of the Earth were too small or too big?
Q10. Does the magnetic field of the Earth have any role in sustaining life on Earth?
Q11. But, how is life supported and sustained on Earth?
Q12. Can you observe and list some plants around you that grow this way?
Q13. How do bamboo and sugarcane grow into new plants? I have never seen their seeds.
Q14. Is the temperature or distance from the Sun, the only factor that makes the Earth habitable?
Q15. What would happen if the size of the Earth were too small or too big?
Medium Questions
Q1. 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?
Q2. 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?
Q3. 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 using what you’ve learnt in this and other chapters of your science book?
Q4. Imagine Earth’s magnetic field suddenly disappeared. What kinds of problems could arise for life on Earth? Explain.
Q5. You are tasked with designing a new settlement for humans on Mars. Name three things you would need to recreate from Earth to support human life there. Which of these do you think is the hardest to replicate, and why?
Q6. In a village, the temperature has been increasing and rainfall has become unpredictable over the past few years. What could be causing this change? Suggest two ways the village could adapt to these new conditions.
Q7. If there were no atmosphere on the Earth, would it affect life, temperature, and water on the planet? Explain.
Q8. Discuss five examples of vegetative propagation.
Q9. Design an ‘Earth Survival Kit’. Imagine you’re building a tiny model of Earth for another planet. What must it have to support life, and why?
Q10. India is planning for a challenging lunar mission, Chandrayaan-4, which will bring back samples of soil from the Moon. If the Moon had water, could plants grow in that soil? Think of some experiment that could help you explore whether plant growth is possible on the Moon.
Q11. Flowers are often brightly coloured and have a pleasant smell. How do you think these features help the plant reproduce?
Q12. Why do animals like fish and frogs lay hundreds or even thousands of eggs at a time, while other animals lay only a few? What might be the advantages and disadvantages of laying so many eggs?
Q13. Birds like sparrows build nests and care for their eggs and chicks, while reptiles like snakes usually lay their eggs and leave them without protection. How might this difference in parental care affect the chances of survival for the young ones in each case?
Q14. What do you think Earth would look like if there were no life on it at all?
Q15. Life on Earth has survived for billions of years. What allows it to keep going despite major changes and disasters?
Long Questions
Q1. What is one major reason Mars cannot currently support life like Earth?
Q2. Which of these is an example of geodiversity?
Q3. If the Earth were smaller with the same density, what might happen to its atmosphere?
Q4. In sexual reproduction, why are offspring different from their parents?
Q5. 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?
Q6. 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?
Q7. 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 using what you’ve learnt in this and other chapters of your science book?
Q8. Imagine Earth’s magnetic field suddenly disappeared. What kinds of problems could arise for life on Earth? Explain.
Q9. You are tasked with designing a new settlement for humans on Mars. Name three things you would need to recreate from Earth to support human life there. Which of these do you think is the hardest to replicate, and why?
Q10. In a village, the temperature has been increasing and rainfall has become unpredictable over the past few years. What could be causing this change? Suggest two ways the village could adapt to these new conditions.
Q11. If there were no atmosphere on the Earth, would it affect life, temperature, and water on the planet? Explain.
Q12. Discuss five examples of vegetative propagation.
Q13. Design an ‘Earth Survival Kit’. Imagine you’re building a tiny model of Earth for another planet. What must it have to support life, and why?
Q14. Flowers are often brightly coloured and have a pleasant smell. How do you think these features help the plant reproduce?
Q15. Why do animals like fish and frogs lay hundreds or even thousands of eggs at a time, while other animals lay only a few? What might be the advantages and disadvantages of laying so many eggs?
Interactive Knowledge Quiz
Test your understanding of Our Home: Earth, a Unique Life Sustaining Planet
Quick Revision Notes
Earth's Uniqueness
- Thin crust for life
- Habitable zone
- Liquid water
Factors for Life
- Position from Sun
- Size and gravity
- Magnetic field
Sustaining Life
- Atmosphere
- Hydrosphere
- Geosphere
Reproduction
- Asexual: Identical
- Sexual: Variations
- Continuity of life
Exam Strategy Tips
- Focus on definitions
- Understand activities
- Explain threats
- Use diagrams
- Link to real life
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