NCERT Solutions for Class 8 Science Chapter 13 Our Home: Earth, a Unique Life Sustaining Planet

Earth is a unique life-sustaining planet because it has liquid water, suitable temperature, atmosphere, gravity and protective natural systems.

NCERT Solutions for Class 8 Science Chapter 13 connect this topic with textbook questions on Earth systems, reproduction and environmental threats.

Class 8 Science Chapter 13 brings together astronomy, Earth science, biology and environmental science in one final chapter. Students learn why Earth is the only known planet where life exists and thrives. The chapter explains the habitable zone, atmosphere, ozone layer, magnetic field, hydrosphere, geosphere, biosphere, reproduction and the triple planetary crisis. For students following the CBSE 2026-27 Science syllabus, these NCERT Solutions for Class 8 Science Chapter 13 are useful because the questions test reasoning more than recall. Answers need cause-effect links, correct terms and examples from the Curiosity textbook.

Key Takeaways

• Earth’s position: Earth lies in the habitable zone where water can remain mostly liquid.
• Atmosphere: Earth’s atmosphere provides oxygen, traps useful heat and supports weather.
• Reproduction: Sexual reproduction creates variation by mixing genes from two parents.
• Triple planetary crisis: Climate change, biodiversity loss and pollution threaten life on Earth.

NCERT Solutions for Class 8 Science Chapter 13 Structure 2026-27

NCERT Solutions for Class 8 Science Chapter 13 Exercise Answers

The 2026-27 Curiosity textbook has 12 main questions in Class 8 Science Chapter 13 after the snapshots section. These class 8 science chapter 13 solutions follow the textbook order and use direct reasoning.

Q1. What is one major reason Mars cannot currently support life like Earth?

The correct answer is (iii) It lacks a thick atmosphere and liquid water.

Mars lies near the edge of the Sun’s habitable zone. However, its atmosphere is very thin and liquid water is not present on its surface today.

A thick atmosphere helps a planet retain heat and protect life. Liquid water is also essential for most known life forms.

Q2. Which of these is an example of geodiversity?

The correct answer is (ii) Different landforms like mountains, valleys, and deserts.

Geodiversity means the variety of non-living Earth features. It includes landforms, rocks, minerals, soils and the processes that shape them.

Birds and fish belong to biodiversity. Weather change is related to atmosphere and climate.

Q3. If the Earth were smaller with the same density, what might happen to its atmosphere?

The correct answer is (ii) It would escape into space due to weaker gravity.

A smaller Earth would have weaker gravity if its average density stayed the same. Weak gravity would not hold atmospheric gases strongly.

This is why Earth’s size is important for life. It helps Earth keep the air needed for breathing and temperature balance.

Q4. In sexual reproduction, why are offspring different from their parents?

The correct answer is (iv) They get mixed instructions, or genes, from both parents.

In sexual reproduction, male and female gametes carry genetic material from two parents. These instructions combine during fertilisation.

This mixing creates variation. That is why children may resemble parents but are not exact copies.

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?

The seeds may have come from birds, wind, animals or nearby plants. Birds may eat fruits and drop seeds through their waste.

The monsoon provided water for germination. Dust and soil collected in wall cracks gave the seeds minerals and support.

Sunlight, air and moisture helped the seedlings grow. These are the basic conditions needed for plant growth.

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?

Cutting a large forest can increase local temperature and reduce rainfall support. Trees cool the air through shade and water loss from leaves.

Biodiversity will fall because many plants, birds, insects and animals lose their habitat. Food chains may also get disturbed.

Water availability can reduce because fewer trees means less water retention in soil. Water quality may also worsen due to soil erosion and polluted runoff.

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?

Earth has had natural climate changes in the past, but present global warming is happening faster because of human activities. Burning coal, oil and gas releases extra greenhouse gases.

Carbon dioxide and methane trap more heat in the atmosphere. This increases Earth’s average temperature.

The problem is the speed and cause of the change. Rapid warming can disturb rainfall, crops, sea levels, glaciers, wildlife and human health.

Q8. Imagine Earth’s magnetic field suddenly disappeared. What kinds of problems could arise for life on Earth? Explain.

Earth would lose an important protective shield against solar wind and cosmic rays. These high-energy particles can damage the atmosphere.

The ozone layer may also get affected. More harmful ultraviolet rays could then reach Earth’s surface.

Living cells can be damaged by strong radiation. Over time, life on Earth would face serious survival risks.

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?

A Mars settlement would need breathable air, liquid water and controlled temperature. It would also need food production and radiation protection.

The hardest condition to recreate is a stable Earth-like atmosphere. It must provide oxygen, maintain pressure, regulate temperature and protect people from radiation.

A closed settlement can supply oxygen and water for a small group. Recreating a full atmosphere for a planet is much harder.

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.

The change could be linked to climate change. Rising greenhouse gases can affect temperature, rainfall and weather patterns.

The village can adapt by storing rainwater through tanks, ponds and recharge pits. This helps during dry periods.

Farmers can also grow crops that need less water. They can use drip irrigation to reduce water wastage.

Q11. If there were no atmosphere on the Earth, would it affect life, temperature and water on the planet? Explain.

Yes, life, temperature and water would all be affected without the atmosphere. Earth would lose the air needed for respiration.

The atmosphere traps some heat through the greenhouse effect. Without it, Earth would become much colder.

Water would also be affected because the water cycle depends on evaporation, clouds and rainfall. Harmful solar radiation would reach the surface more easily.

Q12. Discuss five examples of vegetative propagation.

Vegetative propagation is asexual reproduction through roots, stems, leaves or buds. A single parent plant produces a new plant.

1. Potato: New plants grow from the eyes of a potato tuber.
2. Ginger: New shoots grow from underground stem pieces.
3. Money plant: A stem cutting can grow roots in water or soil.
4. Sugarcane: Stem cuttings with nodes grow into new plants.
5. Bryophyllum: New plantlets grow from the edges of leaves.

These plants do not need seeds for this method. They grow from vegetative parts of the parent plant.

Class 8 Science Chapter 13 Concepts Behind the NCERT Solutions

Class 8 Science Curiosity Chapter 13 explains Earth through connected systems rather than isolated facts. These concepts help students write better class 8 science chapter 13 question answer responses in school exams.

Habitable Zone and the Goldilocks Zone

The habitable zone is the region around a star where liquid water can exist. In goldilocks zone class 8 questions, students should write that Earth is neither too hot nor too cold.

Earth lies at the right distance from the Sun. This allows water to remain mostly liquid in oceans, rivers, lakes and groundwater.

If Earth were closer to the Sun, water could evaporate. If it were farther away, water could freeze.

Greenhouse Effect Keeps Earth Warm

The greenhouse effect class 8 concept explains how gases trap some heat given off by Earth. Carbon dioxide is one important greenhouse gas.

This effect is useful when it keeps Earth warm enough for liquid water. It becomes harmful when extra gases trap too much heat.

Venus is the hottest planet because its thick carbon dioxide atmosphere traps heat strongly. This explains why Venus is hotter than Mercury.

Air, Water and Sunlight Support Life

Plants use carbon dioxide, water and sunlight to make food by photosynthesis. Oxygen is released during this process.

The basic word equation is:

Carbon dioxide + Water → Food + Oxygen

Carbon dioxide and water combine in the presence of sunlight to produce food and oxygen.

Hydrosphere, Geosphere and Biosphere Work Together

The hydrosphere includes Earth’s water in oceans, rivers, lakes, ponds and groundwater. Water covers about 70 per cent of Earth’s surface.

The geosphere includes rocks, soil, minerals and landforms. Soil provides nutrients such as nitrogen and potassium for plant growth.

The biosphere includes all living beings and their habitats. It connects plants, animals, microbes and their surroundings.

Magnetic Field of Earth Protects Life

The magnetic field of earth class 8 concept shows why Earth is safer than many planets. Earth’s magnetic field acts like a shield against harmful particles from space.

These particles include solar wind and cosmic rays. They can damage the atmosphere and affect the ozone layer.

The magnetic field helps protect Earth’s atmosphere. This makes it important for the survival of life.

Reproduction Keeps Life Continuing

Reproduction prevents life forms from disappearing. It allows organisms to produce new individuals of their own kind.

Asexual reproduction involves one parent. The offspring are almost exact copies of the parent.

Sexual reproduction involves two parents. It creates variation because genetic material from both parents combines.

NCERT Solutions for Class 8 Science Chapter 13 Important Terms

The important terms in Our Home Earth Class 8 help students answer short and long questions accurately. These terms are useful for curiosity class 8 science chapter 13 solutions and quick revision.

NCERT Solutions for Class 8 Science Chapter 13 Key Terms

Habitable Zone

The habitable zone is the region around a star where water can remain liquid. Earth lies in this zone around the Sun.

This is why the habitable zone class 8 topic is linked with Earth’s suitability for life. Liquid water is essential for most known life forms.

Goldilocks Zone

The Goldilocks zone is another name for the habitable zone. It means a planet is neither too hot nor too cold for liquid water.

Earth lies in this zone around the Sun. That is why water can remain in liquid form.

Ozone Layer

The ozone layer is a protective part of Earth’s atmosphere. It blocks harmful ultraviolet rays from the Sun.

Ozone is made of three oxygen atoms. It helps protect living cells from radiation damage.

Geodiversity

Geodiversity means the variety of rocks, soils, minerals and landforms on Earth. Mountains, valleys, deserts and different soil types are examples.

This variety creates different habitats. It helps many kinds of life survive in different places.

Vegetative Propagation

Vegetative propagation class 8 refers to asexual reproduction in plants. New plants grow from roots, stems, leaves or buds.

Examples include potato, ginger, money plant, sugarcane and Bryophyllum. These examples are useful for one-mark and three-mark answers.

Fertilisation

Fertilisation is the joining of male and female gametes. It forms a zygote.

In plants, pollen carries male gametes and ovules contain female gametes. In animals, sperm and egg combine to form the zygote.

Triple Planetary Crisis

Triple planetary crisis class 8 refers to climate change, biodiversity loss and pollution. These three threats disturb Earth’s natural balance.

Climate change affects rainfall and temperature. Biodiversity loss weakens ecosystems, while pollution harms air, water and soil.