Start by reviewing these Class 8 Science Curiosity Solutions Chapter 13 Our Home Earth A Unique Life Sustaining Planet Question Answer to strengthen your knowledge.
Class 8 Science Curiosity Chapter 13 Question Answer
Class 8 Science Ch 13 Our Home Earth A Unique Life Sustaining Planet Question Answer
Class 8 Science Chapter 13 Our Home Earth A Unique Life Sustaining Planet Question Answer (InText)
Question 1.
What do you think Earth would look like if there were no life on it at all? (Page 210)
Answer:
Earth would look dull, dry and lifeless. There would be no green plants, no animals, no blue oceans full of life just rocks, soil, water and air with no movement or change.
Question 2.
Life on Earth has survived for billions of years. What allows it to keep going despite major changes and disasters? (Page 210)
Answer:
Life continues because Earth has the right conditions like water, air, sunlight and a balanced system where living things adapt and support each other.
Question 3.
Why don’t dogs lay eggs? Or hens give birth to live chicks? (Page 210)
Answer:
Different animals have different ways of reproducing. Dogs are mammals, so they give birth to babies. Hens are birds, so they lay eggs. Each follows the system nature has given them.
Question 4.
If a spaceship carried soil and water to Mars, could plants start growing there? (Page 210)
Answer:
Not easily. Plants also need air (especially carbon dioxide), the right temperature and sunlight. Mars doesn’t have all these, so plants may not survive without special support.
Question 5.
What makes the Earth unique for living beings to grow and survive? (Page 212)
Answer:
Earth is special because it has everything life needs air to breathe, water to drink, sunlight for energy and soil for plants to grow. It also has the right temperature, a protective atmosphere and magnetic field that keeps harmful space rays away. All these together make Earth the perfect home for living beings.
Question 6.
Is the temperature or distance from the Sun the only factor that makes the Earth habitable? (Page 215)
Answer:
No, just the right distance from the Sun is important, but not the only factor. Earth is habitable because it also has an atmosphere, liquid water, oxygen, soil, a magnetic field and a balanced system that supports life.
Question 7.
What would happen if the size of the Earth were too small or too big? Page 215
Answer:
If Earth were too small, it wouldn’t have enough gravity to hold its atmosphere, like Mercury or Mars. If it were too big, its gravity would be too strong and living things might be crushed or unable to move freely.
Question 8.
Does the magnetic field of the Earth have any role in sustaining life on Earth? Page 217
Answer:
Yes, the Earth’s magnetic field plays a very important role. It protects life by blocking harmful particles from space, like cosmic rays and solar wind. These particles can damage the ozone layer and harm living cells. The magnetic field acts like a shield, helping to keep Earth safe and its atmosphere stable which is essential for life to survive.
Question 9.
How do bamboo and sugarcane grow into new plants? I have never seen their seeds. (Page 221)
Answer:
Bamboo and sugarcane usually grow through a process called vegetative reproduction. This means they don’t need seeds. New plants grow from parts like the stem. Farmers plant a piece of sugarcane or bamboo stem (called a cutting) and it grows into a new plant because it already has buds or nodes that can develop into roots and shoots.
Our Home Earth A Unique Life Sustaining Planet Class 8 Questions and Answers (Exercise)
Question 1.
What is one major reason Mars cannot currently support life like Earth?
(a) It has too many volcanoes.
(b) It is too close to the Sun.
(c) It lacks a thick atmosphere and liquid water.
(d) Its magnetic field is too strong
Answer:
(c) It lacks a thick atmosphere and liquid water.
Question 2.
Which of these is an example of geodiversity?
(a) Variety of bird chirping in a forest.
(b) Different landforms like mountains, valley and deserts.
(c) Changing weather during monsoons.
(d) Number of different types of fish in a pond.
Answer:
(b) Different landforms like mountains, valley and deserts.
Question 3.
If the Earth were smaller with the same density what might happen to its atmosphere?
(a) It would become thicker and hotter.
(b) It would escape into space due to weaker gravity.
(c) It would become frozen.
(d) It would cause stronger winds
Answer:
(b) It would escape into space due to weaker gravity.
Question 4.
In sexual reproduction, why are offspring different from their parents?
(a) They grow in different climates.
(b) They eat different food.
(c) They acquire new instructions after birth.
(d) They get mixed instructions (genes) from both parents.
Answer:
(d) They get mixed instructions (genes) from both parents.
Question 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:
The seeds may have come from wind, birds, or insects. Moisture, sunlight, and air helped the plants grow in the cracks.
Question 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:
Cutting trees can reduce rainfall, increase temperature, and disturb biodiversity. It may reduce water availability and pollute nearby water bodies due to soil erosion.
Question 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 using what you’ve learnt in this and other chapters of your science book?
Answer:
Earth had climate changes in the past, but today’s warming is faster and caused by human activities like pollution and deforestation.
Question 8.
Imagine Earth’s magnetic field suddenly disappeared. What kinds of problems could arise for life on Earth? Explain.
Ans.
Harmful space particles would reach Earth. It could damage the ozone layer and harm living things.
Question 9.
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?
Answer:
We would need air, water and warmth. Recreating breathable atmosphere would be the hardest because Mars lacks it naturally.
Question 10.
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.
Answer:
Climate change could be the reason. The village could plant more trees and store rainwater to adapt.
Question 11.
If there were no atmosphere on the Earth, would it affect life, temperature and water on the planet? Explain.
Answer:
Temperature would be extreme. Water might evaporate or freeze. Life would not survive.
Question 12.
Discuss five examples of vegetative propagation.
Answer:
Money plant (stem cutting), potato (eyes), ginger (underground stem), onion (bulb), bryophyllum (leaf buds).
Class 8 Science Chapter 13 Question Answer (Activities)
Activity 1 (Page 212)
Aim
To identify and understand some unique features of Earth that we often take for granted but are important for sustaining life.
Materials Required
- Textbook (Chapters 5, 7 and 13)
- Notebook or worksheet for Table 13.1
- Pen/pencil
- Group discussion or teacher interaction (optional)
Observation
After reading the textbook and discussing with classmates or teacher, we noted the following interesting features
| S. No. | Feature |
| 1. | The air we breathe stays around Earth and doesn’t escape into space. |
| 2. | We are held to the ground by gravity, but our body functions (like pumping blood upward) still work. |
| 3. | Earth has the right temperature range that allows water to remain in liquid form. |
| 4. | Oxygen in the air supports breathing, while carbon dioxide supports plants. |
| 5. | The magnetic field of Earth protects us from harmful space particles. |
| 6. | The ozone layer blocks dangerous ultraviolet rays from the Sun. |
| 7. | Soil on Earth is rich in nutrients that help plants grow. |
| 8. | The greenhouse effect keeps Earth warm enough to support life. |
Conclusion
Earth has many unique features that make it suitable for life. These include its gravity, breathable atmosphere, protective layers, right temperature and nutrient-rich soil. While we experience these things every day, they are special and necessary for our survival. This activity helps us appreciate the many ways Earth supports life and why we must protect it.
Viva Questions
- Why doesn’t the air on Earth fly off into space?
- What allows our heart to pump blood upwards even against gravity?
- Name one invisible layer that protects us from harmful Sun rays.
Activity 2 (Page 213)
Aim
To collect and compare the temperature, size and atmosphere of different planets in the solar system and understand why Venus is the hottest planet.
Materials Required
- Textbook or reference books on the solar system
- Internet (optional and with guidance)
- Notebook and pen
- Help from teacher (if needed)
Procedure
- Collect information about the average temperature and size (radius compared to Earth) of the planets.
- Check if each planet has an atmosphere or not.
- Fill in the missing details in table given in observations using your findings.
- Look for any pattern related to a planet’s distance from the Sun and its temperature.
- Compare Venus with other nearby planets and find out why it is the hottest.
Observations
| S. No | Planet | Average Temperature (°C) | Radius (compared to Earth) | Has an atmosphere? |
| 1. | Mercury | 170 | 0.39 | No |
| 2. | Venus | 450 | 0.95 | Yes |
| 3. | Earth | 15 | 1 | Yes |
| 4. | Mars | -60 | 0.53 | Yes |
| 5. | Jupiter | -110 | 11 | Yes |
| 6. | Saturn | -140 | 9.4 | Yes |
| 7. | Uranus | -195 | 4 | Yes |
| 8. | Neptune | -200 | 3.9 | Yes |
Conclusion
Planets closer to the Sun are generally hotter and those farther away are colder. However, Venus, which is the second planet from the Sun, is the hottest planet, even hotter than Mercury. This is because Venus has a thick atmosphere rich in carbon dioxide, which traps heat through the greenhouse effect. Therefore, a planet’s atmosphere plays a major role in its temperature not just its distance from the Sun.
Viva Questions
- Which planet is the hottest in the solar system?
- Why is Venus hotter than Mercury, even though Mercury is closer to the Sun?
- What is the average temperature of Earth?
Activity 3 (Page 221)
Aim
To observe how new plants can grow from different parts of existing plants such as stem cuttings, potato eyes and ginger pieces.
Materials Required
- A stem cutting of a money plant.
- A sprouted potato (with visible eyes)
- A piece of ginger with buds
- Small pots or containers with moist soil
- A glass jar for the money plant (optional)
- Water
- Access to sunlight and air
Procedure
- Take a stem cutting of a money plant, a sprouted potato and a ginger piece.
- Plant each of them separately in moist soil. Do not bury them too deep.
- Place the money plant cutting in a glass jar with water, if possible, for better observation.
- Keep all containers in a place where they get sunlight, air and regular water.
- Observe the plants daily.
- Record the number of days it takes for roots, stems and new leaves to appear.
Observation
- Roots started appearing from the money plant cutting after about 5 – 7 days.
- The potato eyes began sprouting stems and leaves in 6 – 8 days.
- Ginger piece showed new shoots in around 7 – 10 days.
- The first new leaf appeared in all three samples between 7 – 12 days, depending on conditions.
Conclusion
New plants can grow from different parts of a parent plant such as stems (money plant), underground stems (ginger) or buds (potato eyes). This activity shows that plants can reproduce even without seeds, using parts like stems, buds and roots, if proper conditions like water, air and sunlight are provided.
Viva Questions
- What is an eye in a potato?
- What do we observe first in the planted parts roots, stems or leaves?
- Can new plants grow without seeds in this method?