CBSE Class 8 Science Chapter 13 Our Home Earth, A Unique Life Sustaining Planet MCQs Set 03

Multiple Choice Questions (MCQs) for Class 8 Science: Chapter 13 Our Home Earth, A Unique Life Sustaining Planet

Explore reliable objective questions for Chapter 13 Our Home Earth, A Unique Life Sustaining Planet tailored for Class 8 learners. Utilizing these Science multiple-choice formats ensures thorough preparation and strengthens problem-solving speed for upcoming school assessments.

Practice Chapter 13 Our Home Earth, A Unique Life Sustaining Planet MCQs for Class 8 Science

Access the complete set of multiple-choice questions for Chapter 13 Our Home Earth, A Unique Life Sustaining Planet below. This focused format allows students to isolate specific topics for thorough review and uninterrupted practice alongside official CBSE textbooks.

Question: When comparing Earth to other planets in the solar system, which characteristic makes Earth's position relative to the Sun fundamentally important for sustaining life?
A. Its great distance from the Sun prevents harmful solar radiation
B. Its location allows water to remain predominantly in liquid form
C. Its proximity to the Sun ensures constant energy supply for photosynthesis
D. Its orbital speed prevents extreme temperature fluctuations
Show Answer & Explanation

Answer: (B) Its location allows water to remain predominantly in liquid form

Explanation:
Earth orbits at precisely the right distance where temperatures permit water to exist as a liquid—crucial for life. Too close, and water evaporates; too far, and it freezes. This range is called the habitable zone.

Question: The chapter compares Earth's crust to the skin of an apple. What does this analogy emphasize about where life on Earth actually exists?
A. Life extends deep into Earth's interior where it is protected
B. The crust is remarkably thick and can support diverse life forms
C. All of life occupies an extremely thin layer relative to Earth's overall size
D. The crust is as fragile as apple skin and easily damaged
Show Answer & Explanation

Answer: (C) All of life occupies an extremely thin layer relative to Earth's overall size

Explanation:
The analogy illustrates that despite hosting all mountains, oceans, forests, and creatures, the living layer—from the highest peaks to deepest trenches—is proportionally paper-thin compared to Earth as a whole.

Question: Which statement best explains why Earth can retain a protective atmosphere while Mars cannot, despite both being rocky planets?
A. Mars is too close to the Sun and heat escapes the atmosphere
B. Earth's greater size and gravity are strong enough to hold gases, whereas Mars's gravity is too weak
C. Mars lacks oxygen in its atmosphere, causing gases to drift away
D. Earth's magnetic field actively pushes gases inward
Show Answer & Explanation

Answer: (B) Earth's greater size and gravity are strong enough to hold gases, whereas Mars's gravity is too weak

Explanation:
• Earth's size creates sufficient gravitational pull to retain atmospheric gases
• Mars, being smaller, has weaker gravity that cannot hold onto light gas molecules
• These gases gradually escape into space, leaving Mars with an atmosphere 100 times thinner than Earth's

Question: How does the process of sexual reproduction create variation in offspring in a way that asexual reproduction does not?
A. Sexual offspring acquire new traits after birth through learning
B. Each parent contributes half their genetic instructions, creating a unique combination in each offspring
C. Sexual reproduction produces more offspring than asexual reproduction
D. Variation only occurs in animals, not in plants
Show Answer & Explanation

Answer: (B) Each parent contributes half their genetic instructions, creating a unique combination in each offspring

Explanation:
In sexual reproduction, genetic material from two parents mixes differently each time, producing offspring that are unique combinations—similar to siblings looking different from each other and their parents. Asexual reproduction creates identical copies.

Question: What role does the ozone layer serve in relation to ultraviolet rays from the Sun?
A. It attracts UV rays toward Earth's surface
B. It converts harmful UV rays into visible light that is safe for organisms
C. It acts as a shield that blocks most harmful UV rays from reaching the surface
D. It absorbs UV rays and converts them into heat energy
Show Answer & Explanation

Answer: (C) It acts as a shield that blocks most harmful UV rays from reaching the surface

Explanation:
Some oxygen in the atmosphere converts to ozone, forming a protective layer that acts as a barrier, preventing dangerous ultraviolet radiation from reaching living organisms below.

Question: According to the chapter, which statement correctly describes the relationship between carbon dioxide, heat, and the greenhouse effect on Earth?
A. Carbon dioxide repels heat back toward space, cooling the planet
B. Carbon dioxide in the atmosphere traps heat by absorbing radiation from the warmed Earth, keeping the temperature suitable for life
C. Carbon dioxide prevents the Sun's radiation from reaching Earth
D. Carbon dioxide enhances the atmosphere's ability to cool the planet at night
Show Answer & Explanation

Answer: (B) Carbon dioxide in the atmosphere traps heat by absorbing radiation from the warmed Earth, keeping the temperature suitable for life

Explanation:
Greenhouse gases like carbon dioxide absorb heat radiation released by Earth after the Sun warms it, trapping this heat in the atmosphere. This maintains temperatures in a range suitable for life, though excess carbon dioxide causes harmful warming.

Question: In flowering plants, what sequence of events leads to the formation of a seed?
A. Pollen is produced in the ovule, then travels to the anther to create a zygote
B. Pollen from the anther is carried to the ovule of another flower through pollination, then gametes combine in fertilisation to form a zygote that becomes a seed
C. The ovule produces pollen that fertilises the anther, creating the seed coat
D. Seeds form directly from the flower petals without requiring pollination
Show Answer & Explanation

Answer: (B) Pollen from the anther is carried to the ovule of another flower through pollination, then gametes combine in fertilisation to form a zygote that becomes a seed

Explanation:
Male gametes in pollen grains (from the anther) reach female gametes in the ovule via pollination. When these unite during fertilisation, the resulting zygote develops into a seed. The fleshy part around the ovule becomes fruit.

Question: Why would a scientist studying biodiversity loss be concerned about the destruction of large forests, based on the chapter's explanation of ecosystem relationships?
A. Forests are the only source of oxygen for the planet
B. Removing forests has no effect on other organisms since they can find new habitats elsewhere
C. Loss of vegetation affects herbivores that depend on it for food, and this disruption spreads through the food chain, weakening ecosystems
D. Forests absorb too much carbon dioxide and removing them helps reduce climate change
Show Answer & Explanation

Answer: (C) Loss of vegetation affects herbivores that depend on it for food, and this disruption spreads through the food chain, weakening ecosystems

Explanation:
The chapter illustrates that when grasses vanish, herbivores like deer struggle, and without herbivores, predators lose their food source. Each organism plays a role; removing even some species weakens nature's ability to support life.

Question: What does the chapter identify as the primary source of Earth's magnetic field?
A. The rotation of Earth around the Sun
B. Movement of molten iron in Earth's core
C. Interaction between the atmosphere and solar wind
D. The decay of radioactive minerals in the crust
Show Answer & Explanation

Answer: (B) Movement of molten iron in Earth's core

Explanation:
It is believed that the motion of molten iron in Earth's core generates the planet's magnetic field, which acts as a protective shield against harmful cosmic rays and solar wind particles.

Question: In the context of reproduction, what advantage does sexual reproduction provide that asexual reproduction does not, according to the chapter?
A. Sexual reproduction produces more offspring faster
B. Sexual reproduction allows variation and new traits to appear, helping species adapt to changing environments over generations
C. Sexual reproduction uses less energy than asexual reproduction
D. Sexual reproduction is simpler and requires fewer parents
Show Answer & Explanation

Answer: (B) Sexual reproduction allows variation and new traits to appear, helping species adapt to changing environments over generations

Explanation:
Sexual reproduction enables mixing of genetic instructions from two parents, creating variation. Over many generations, these small differences can lead to new features and adaptations—like camels developing humps to survive in deserts—whereas asexual reproduction creates identical copies.

Question: How does the chapter explain the difference between how a bird's egg and a mammal's embryo receive nutrition during development?
A. Birds' eggs contain no nutrition; mammals provide all nutrients internally
B. In birds, the female packs enough stored food into each egg to sustain the developing embryo until hatching, while in mammals the mother's body provides ongoing food and oxygen through internal development
C. Birds and mammals use identical nutritional strategies during development
D. Mammals' embryos obtain nutrition from soil through the placenta
Show Answer & Explanation

Answer: (B) In birds, the female packs enough stored food into each egg to sustain the developing embryo until hatching, while in mammals the mother's body provides ongoing food and oxygen through internal development

Explanation:
The chapter contrasts two strategies: birds must pack all necessary nutrition into the egg before it is laid, whereas mammals develop internally where the mother continuously supplies food and oxygen until birth—different solutions to the same problem of nourishing the developing offspring.

Question: Which statement best captures why the chapter describes the balance between living and non-living things on Earth as 'delicate'?
A. The balance is so strong it cannot be disrupted by human actions
B. Even small changes in temperature, oxygen levels, or the ozone layer can threaten life, yet human activities are increasingly disturbing this balance
C. The balance only applies to plants and animals, not to water or air
D. Nature automatically repairs any damage, so the balance requires no protection
Show Answer & Explanation

Answer: (B) Even small changes in temperature, oxygen levels, or the ozone layer can threaten life, yet human activities are increasingly disturbing this balance

Explanation:
Earth's life-support systems are finely tuned: water remains liquid in a narrow temperature range, the ozone layer shields against UV rays, and oxygen supports respiration. Small disruptions from burning fossil fuels, habitat destruction, and pollution can cascade through ecosystems and put life at risk.

Question: What do scientists infer about Mars based on evidence presented in the chapter, and why does this continue to interest them?
A. Mars is known to currently host thriving microbial colonies similar to Earth's
B. In the past, Mars may have had liquid water and conditions suitable for simple life, making it relevant for understanding whether habitability can exist beyond Earth
C. Mars is too hot for any form of life and has never been suitable for living organisms
D. Scientists have found definitive proof of past civilisations on Mars
Show Answer & Explanation

Answer: (B) In the past, Mars may have had liquid water and conditions suitable for simple life, making it relevant for understanding whether habitability can exist beyond Earth

Explanation:
Though no proof of life has been found, scientists believe Mars once had liquid water and potentially habitable conditions. This possibility keeps Mars central to the search for extraterrestrial life and our understanding of what makes planets suitable for life.

Question: According to the chapter, how do gametes solve the potential problem of genetic material doubling with each generation in sexual reproduction?
A. Gametes combine multiple copies to strengthen offspring
B. Each gamete carries only half the parent's genetic material, so when male and female gametes join, the offspring receives a complete set—half from each parent—rather than a doubled amount
C. Gametes discard excess genetic material before reproduction
D. Offspring reject half of their genetic material after birth
Show Answer & Explanation

Answer: (B) Each gamete carries only half the parent's genetic material, so when male and female gametes join, the offspring receives a complete set—half from each parent—rather than a doubled amount

Explanation:
If parents passed on complete genetic material, the child would have double instructions, and this would keep doubling. Instead, specialised cells (gametes) carry only half, ensuring that when they combine, the zygote has one complete, balanced set of instructions.

Question: What does the chapter suggest would be the most difficult condition to recreate if humans were to establish a settlement on Mars, and why?
A. Building shelter from rocks and dust
B. Creating breathable air with the right atmosphere and liquid water for life processes, since Mars lacks both a thick atmosphere and evidence of liquid water
C. Growing food in Martian soil alone
D. Protecting humans from occasional dust storms
Show Answer & Explanation

Answer: (B) Creating breathable air with the right atmosphere and liquid water for life processes, since Mars lacks both a thick atmosphere and evidence of liquid water

Explanation:
The chapter emphasises that Earth's thick atmosphere and abundant liquid water are critical for life. Mars has an extremely thin atmosphere (100 times thinner than Earth's) and no confirmed liquid water. These conditions—essential for respiration, photosynthesis, and biological processes—would be the hardest to recreate.

Question: When comparing Earth to Jupiter and Saturn, what is the fundamental difference in planetary composition that the chapter emphasizes?
A. Jupiter and Saturn are made entirely of rock like Earth
B. Jupiter and Saturn are large gas planets while Earth is a small rocky planet
C. Earth is larger than Jupiter but made of different materials
D. Jupiter and Saturn have thicker atmospheres than Earth
Show Answer & Explanation

Answer: (B) Jupiter and Saturn are large gas planets while Earth is a small rocky planet

Explanation:
The chapter explicitly states that Mercury, Venus, Earth, and Mars are relatively small and rocky planets, while Jupiter, Saturn, Uranus, and Neptune are large planets mostly made of gases. This compositional difference is a key distinction between the inner and outer planets of our solar system.

Question: Why does the chapter describe Earth's crust as 'delicate' despite it being made of solid rock and minerals?
A. Rock naturally breaks apart over time without support
B. It is incredibly thin compared to Earth's total size, yet it is where all life exists
C. The minerals in the crust are softer than those on other planets
D. It contains many water-filled cavities that weaken its structure
Show Answer & Explanation

Answer: (B) It is incredibly thin compared to Earth's total size, yet it is where all life exists

Explanation:
The analogy of Earth's crust being as thin as an apple's skin illustrates that this layer supporting all life—from the tallest mountains to the deepest ocean trenches—is tiny in proportion to Earth's size. This disparity makes it vulnerable and worthy of protection.

Question: Based on the chapter's description of how plants and animals interact in an ecosystem, what would most likely happen if all decomposers disappeared from an environment?
A. Plants would grow faster without competition for nutrients
B. Dead matter would accumulate and nutrients would not return to soil for plant growth
C. Animals would need to eat more plants to survive
D. The temperature would increase due to less organic material breaking down
Show Answer & Explanation

Answer: (B) Dead matter would accumulate and nutrients would not return to soil for plant growth

Explanation:
• Decomposers break down dead matter and return nutrients to soil
• Without them, nutrients remain locked in dead organisms
• Plants depend on these recycled nutrients to grow
• The nutrient cycle would collapse, limiting plant growth and indirectly affecting animals that depend on plants.

Question: How does the chapter's explanation of why babies have unique appearances connect to the concept of genetic material from gametes?
A. All babies inherit their mother's genes exclusively
B. Each baby receives a different random mix of instructions from both parents' gametes, making each child unique
C. Babies develop their appearance after birth based on their environment
D. The father's genes always dominate over the mother's genes
Show Answer & Explanation

Answer: (B) Each baby receives a different random mix of instructions from both parents' gametes, making each child unique

Explanation:
The chapter explains that each gamete carries a different set of instructions for traits like eye colour and hair type. When sperm and egg combine, these instructions mix in different ways each time, creating variation. This mixing is why siblings in the same family can look different from each other and from their parents.

Question: What does the chapter suggest would be the consequence if Earth orbited in the region where Venus currently orbits?
A. All water would freeze and life would cease to exist
B. The atmosphere would become thicker and protect us from radiation
C. All water would evaporate due to extreme heat, making life impossible for most organisms
D. We would receive the right amount of energy to sustain current life
Show Answer & Explanation

Answer: (C) All water would evaporate due to extreme heat, making life impossible for most organisms

Explanation:
Earth's position in the habitable zone allows water to remain mostly in liquid form. If Earth were closer to the Sun like Venus, the intense heat would cause all water to evaporate, making it impossible for plants, animals, and humans to survive.

Question: In the context of threats to life on Earth, how are climate change, biodiversity loss, and pollution interconnected according to the chapter?
A. They are separate problems that do not affect each other
B. • Burning fossil fuels releases greenhouse gases causing climate change • Climate change destroys natural habitats, leading to biodiversity loss • Both create conditions for pollution to spread more easily • Together they represent the 'triple planetary crisis'
C. Only climate change matters; the others are minor issues
D. Pollution causes climate change but not biodiversity loss
Show Answer & Explanation

Answer: (B) • Burning fossil fuels releases greenhouse gases causing climate change • Climate change destroys natural habitats, leading to biodiversity loss • Both create conditions for pollution to spread more easily • Together they represent the 'triple planetary crisis'

Explanation:
The chapter describes these three challenges as interconnected parts of one major crisis. Fossil fuel burning releases gases causing temperature rise, which destroys habitats where species live, disrupting ecosystems. Pollution from human activities compounds all these problems simultaneously.

Question: What key distinction does the chapter make between the way a plant greenhouse and Earth's atmosphere trap heat?
A. Both methods work identically and there is no real difference
B. A plant greenhouse traps heat through a closed glass structure, while Earth's atmosphere traps heat by gases absorbing radiation from the warmed planet
C. Earth's atmosphere works better than plant greenhouses at trapping heat
D. Plant greenhouses use carbon dioxide while Earth's atmosphere does not
Show Answer & Explanation

Answer: (B) A plant greenhouse traps heat through a closed glass structure, while Earth's atmosphere traps heat by gases absorbing radiation from the warmed planet

Explanation:
The chapter's 'A step further' section clarifies that a plant greenhouse traps warmed air simply because it is a closed space with glass walls, while on Earth, gases like carbon dioxide in the atmosphere absorb radiation given off by the planet after it is warmed by the Sun. The mechanism and the medium are fundamentally different.

Question: Why does the chapter specifically mention that cosmic rays and solar wind can damage the ozone layer and allow more harmful UV rays to reach Earth?
A. The ozone layer is not actually protective against these particles
B. These high-energy particles are harmful themselves, and if they reach the lower atmosphere, they damage the very layer that shields us from UV radiation
C. Cosmic rays and solar wind create ozone, so reducing them would decrease ozone
D. The ozone layer absorbs these particles but becomes stronger in the process
Show Answer & Explanation

Answer: (B) These high-energy particles are harmful themselves, and if they reach the lower atmosphere, they damage the very layer that shields us from UV radiation

Explanation:
The chapter explains that the magnetic field protects Earth by pushing away these harmful particles. If the magnetic field failed, these particles could damage the atmosphere and reduce the ozone layer, allowing UV rays to harm living cells. This chain of consequences shows why the magnetic field's protection is essential.

Question: According to the chapter, why is the formation of a seed in flowering plants dependent on a sequence involving both pollen and ovules?
A. Pollen and ovules are the same structure with different names
B. Pollen delivers male gametes to the ovule where fertilisation occurs, and the resulting zygote develops into a seed
C. Seeds form without fertilisation in flowering plants
D. Ovules produce both male and female gametes without needing pollen
Show Answer & Explanation

Answer: (B) Pollen delivers male gametes to the ovule where fertilisation occurs, and the resulting zygote develops into a seed

Explanation:
The chapter describes how pollen grains are male gametes produced in the anther, while ovules are female gametes deep inside the flower. When pollen is carried to another flower by wind, insects, or animals, fertilisation occurs between these male and female gametes. The resulting zygote becomes the seed. This dependency on both structures explains why seed formation requires pollination.

Question: How does the chapter use the example of camels developing humps to illustrate a broader principle about reproduction and life on Earth?
A. Asexual reproduction allows animals to design their own body parts
B. Sexual reproduction enables small genetic changes over many generations that help organisms adapt to new environments, showing how life evolves
C. Humps are created by the environment, not by reproduction
D. Camels always had humps from the moment life began on Earth
Show Answer & Explanation

Answer: (B) Sexual reproduction enables small genetic changes over many generations that help organisms adapt to new environments, showing how life evolves

Explanation:
The chapter explains that reproduction allows for small changes in instructions passed from parents to offspring. Over many generations, such changes can lead to new features. The camel's hump development demonstrates how these accumulated small variations enable species to survive better in challenging environments like deserts, illustrating evolution through reproduction.

Free study material for Science

Chapter 13 Our Home Earth, A Unique Life Sustaining Planet Objective Questions & Solutions for Class 8 Science

Download Multiple Choice Questions: Chapter 13 Our Home Earth, A Unique Life Sustaining Planet (Class 8 Science)

Test your conceptual understanding of Chapter 13 Our Home Earth, A Unique Life Sustaining Planet with these targeted multiple-choice questions. Designed in alignment with the latest CBSE curriculum for Class 8 Science, these problem sets build accuracy and prepare students for objective exams.

Concept Clarification for Chapter 13 Our Home Earth, A Unique Life Sustaining Planet

Built using the official NCERT book for Class 8, these Science objective sets provide reliable academic guidance. Pair your practice with our recommended NCERT solutions to master optimal problem-solving approaches.

Additional Study Resources for Class 8 Science

Wrap up your chapter revision by testing your knowledge against standard question formats. Everything on our platform is provided free of charge.

FAQs

Where can I access latest CBSE Class 8 Science Chapter 13 Our Home Earth, A Unique Life Sustaining Planet MCQs Set 03?

You can get most exhaustive CBSE Class 8 Science Chapter 13 Our Home Earth, A Unique Life Sustaining Planet MCQs Set 03 for free on StudiesToday.com. These MCQs for Class 8 Science are updated for the 2026-27 academic session as per CBSE examination standards.

Are Assertion-Reasoning and Case-Study MCQs included in the Science Class 8 material?

Yes, our CBSE Class 8 Science Chapter 13 Our Home Earth, A Unique Life Sustaining Planet MCQs Set 03 include the latest type of questions, such as Assertion-Reasoning and Case-based MCQs. 50% of the CBSE paper is now competency-based.

How do practicing Science MCQs help in scoring full marks in Class 8 exams?

By solving our CBSE Class 8 Science Chapter 13 Our Home Earth, A Unique Life Sustaining Planet MCQs Set 03, Class 8 students can improve their accuracy and speed which is important as objective questions provide a chance to secure 100% marks in the Science.

Do you provide answers and explanations for CBSE Class 8 Science Chapter 13 Our Home Earth, A Unique Life Sustaining Planet MCQs Set 03?

Yes, Science MCQs for Class 8 have answer key and brief explanations to help students understand logic behind the correct option as its important for 2026 competency-focused CBSE exams.

Can I practice these Science Class 8 MCQs online?

Yes, you can also access online interactive tests for CBSE Class 8 Science Chapter 13 Our Home Earth, A Unique Life Sustaining Planet MCQs Set 03 on StudiesToday.com as they provide instant answers and score to help you track your progress in Science.