Question 1. What makes Earth different from the other planets discussed in the lesson?
A. It has the greatest number of moons
B. It is the largest planet
C. It provides conditions that support life
D. It has visible rings
Answer: C. It provides conditions that support life
Question 2. Which set of conditions makes Earth suitable for supporting life?
A. Air, water and soil
B. Only rocks and minerals
C. Only sunlight
D. Only atmospheric gases
Answer: A. Air, water and soil
Question 3. Which of the following is a group of rocky planets?
A. Jupiter, Saturn, Uranus and Neptune
B. Mercury, Venus, Earth and Mars
C. Earth, Jupiter, Saturn and Mars
D. Venus, Neptune, Earth and Uranus
Answer: B. Mercury, Venus, Earth and Mars
Question 4. Which group contains the largest planets of our Solar System?
A. Mercury, Venus, Earth and Mars
B. Earth, Mars, Jupiter and Saturn
C. Jupiter, Saturn, Uranus and Neptune
D. Mercury, Earth, Uranus and Neptune
Answer: C. Jupiter, Saturn, Uranus and Neptune
Question 5. Which planet has the highest average surface temperature in our Solar System?
A. Mercury
B. Venus
C. Mars
D. Earth
Answer: B. Venus
Question 6. Which planet is associated with an extremely strong greenhouse effect caused by a very dense atmosphere?
A. Mars
B. Mercury
C. Venus
D. Jupiter
Answer: C. Venus
Question 7. What is an important role of greenhouse gases in Earth's atmosphere?
A. They remove all heat from Earth.
B. They trap some outgoing heat and help maintain a suitable temperature.
C. They stop sunlight from reaching Earth.
D. They convert oxygen into carbon dioxide.
Answer: B. They trap some outgoing heat and help maintain a suitable temperature.
Question 8. What is the main protective role of the ozone layer?
A. It prevents rainfall.
B. It blocks harmful ultraviolet radiation.
C. It produces oxygen for animals.
D. It attracts cosmic rays.
Answer: B. It blocks harmful ultraviolet radiation.
Question 9. High-energy particles arriving from outer space are referred to as:
A. Solar winds
B. Cosmic rays
C. Water vapours
D. Dust storms
Answer: B. Cosmic rays
Question 10. If Earth were much smaller, which problem would be most likely?
A. Its gravity would become stronger.
B. It would find it difficult to retain its atmosphere.
C. Its magnetic field would become infinitely strong.
D. All water would immediately turn into ice.
Answer: B. It would find it difficult to retain its atmosphere.
Question 11. Which layer of the Earth is the outermost solid layer on which we live?
A. Core
B. Mantle
C. Crust
D. Atmosphere
Answer: C. Crust
Question 12. Which layer protects living organisms from a large part of the Sun's harmful ultraviolet radiation?
A. Mantle
B. Ozone layer
C. Crust
D. Hydrosphere
Answer: B. Ozone layer
Question 13. Earth's magnetic field helps protect the planet mainly from:
A. Rainfall and clouds
B. Solar wind and charged particles
C. Earthquakes
D. Changes in seasons
Answer: B. Solar wind and charged particles
Question 14. Which biological process ensures that a species continues from one generation to the next?
A. Respiration
B. Digestion
C. Reproduction
D. Excretion
Answer: C. Reproduction
Question 15. Which combination of factors contributes significantly to making Earth suitable for life?
A. Proper position from the Sun, suitable size, atmosphere and magnetic field
B. Large rings, many moons and no atmosphere
C. Only a rocky surface and high temperature
D. Absence of water and gases
Answer: A. Proper position from the Sun, suitable size, atmosphere and magnetic field
Question 16. All the water present on Earth, including oceans, rivers, lakes and groundwater, together forms the:
A. Geosphere
B. Hydrosphere
C. Atmosphere
D. Biosphere
Answer: B. Hydrosphere
Question 17. What is the name of the male reproductive cell in animals?
A. Ovum
B. Zygote
C. Sperm
D. Embryo
Answer: C. Sperm
Question 18. The variety of Earth's non-living natural features, such as rocks, soils and landforms, is referred to as:
A. Biodiversity
B. Geodiversity
C. Genetic diversity
D. Atmospheric diversity
Answer: B. Geodiversity
Question 19. What is the main importance of reproduction for living organisms?
A. It ensures continuity of life from one generation to the next.
B. It stops organisms from growing.
C. It prevents genetic information from being passed on.
D. It changes all organisms into the same species.
Answer: A. It ensures continuity of life from one generation to the next.
Question 20. Pollution, climate change and biodiversity loss together are described as the:
A. Three Earth systems
B. Triple planetary crisis
C. Three stages of reproduction
D. Natural protection cycle
Answer: B. Triple planetary crisis
Question 21.
Scientists discover a planet similar to Earth but much smaller in size. The planet has a weak gravitational force.
What is the most likely effect of its weak gravity?
A. It will attract more gases from space.
B. It may be unable to retain its atmosphere.
C. Its surface temperature will always be zero.
D. It will develop a stronger magnetic field.
Answer: B. It may be unable to retain its atmosphere.
Explanation: A smaller planet generally has weaker gravity, making it difficult to hold atmospheric gases around it.
Question 22.
Two planets orbit the same star. Planet X is extremely close to the star, while Planet Y is located at a distance where temperatures allow water to remain liquid.
Which statement best describes Planet Y?
A. It lies outside the Solar System.
B. It is located in the habitable zone.
C. It must be a gaseous planet.
D. It cannot support any form of life.
Answer: B. It is located in the habitable zone.
Explanation: The habitable or Goldilocks zone is the region around a star where conditions may allow liquid water to exist.
Question 23.
Suppose Earth's magnetic field suddenly became extremely weak. Which of the following would be most directly affected?
A. Protection from charged particles coming from the Sun
B. Formation of rocks inside Earth
C. Production of genes in organisms
D. Amount of soil on Earth's surface
Answer: A. Protection from charged particles coming from the Sun
Explanation: Earth's magnetic field helps deflect many charged particles carried by the solar wind.
Question 24.
A planet has an atmosphere similar to Earth's but does not have a protective ozone layer.
Which environmental problem is most likely to increase?
A. Exposure of living organisms to harmful ultraviolet radiation
B. Loss of all liquid water due to gravity
C. Disappearance of rocks and minerals
D. Complete loss of the planet's magnetic field
Answer: A. Exposure of living organisms to harmful ultraviolet radiation
Explanation: The ozone layer absorbs much of the harmful ultraviolet radiation coming from the Sun.
Question 25.
Planet A has a thick atmosphere rich in carbon dioxide, while Planet B has a much thinner atmosphere. Both receive approximately similar amounts of energy from their star.
Which prediction is most reasonable?
A. Planet A may have a higher surface temperature due to a stronger greenhouse effect.
B. Planet B must be hotter because its atmosphere is thinner.
C. Both planets must have exactly the same temperature.
D. Atmospheric composition has no effect on temperature.
Answer: A. Planet A may have a higher surface temperature due to a stronger greenhouse effect.
Explanation: Greenhouse gases such as carbon dioxide can trap outgoing heat and increase surface temperature.
Question 26.
A student is studying oceans, rivers, lakes and groundwater as one interconnected part of Earth.
Which Earth system is the student studying?
A. Geosphere
B. Atmosphere
C. Hydrosphere
D. Biosphere
Answer: C. Hydrosphere
Explanation: The hydrosphere includes all forms of water present on Earth.
Question 27.
A particular species stops reproducing completely. Although the existing organisms continue to live for some time, eventually no individuals of that species remain.
Which conclusion does this situation support?
A. Reproduction is necessary for the continuity of a species.
B. Reproduction protects organisms from ultraviolet radiation.
C. Reproduction produces Earth's atmosphere.
D. Reproduction strengthens gravity.
Answer: A. Reproduction is necessary for the continuity of a species.
Explanation: Reproduction produces new generations and ensures the continuation of life.
Question 28.
A single organism produces offspring without the involvement of another parent or the fusion of specialised reproductive cells.
Which type of reproduction is taking place?
A. Sexual reproduction
B. Asexual reproduction
C. Genetic reproduction
D. Atmospheric reproduction
Answer: B. Asexual reproduction
Explanation: Asexual reproduction involves only one parent and does not require the fusion of gametes.
Question 29.
A child has certain characteristics similar to those of their parents. These characteristics are passed from parents to offspring through specific units of genetic information.
What are these units called?
A. Gametes
B. Genes
C. Minerals
D. Tissues
Answer: B. Genes
Explanation: Genes carry hereditary information from parents to offspring.
Question 30.
A student claims that the presence of water alone is enough to make a planet suitable for life. Another student argues that several conditions must work together.
Which statement is scientifically more appropriate?
A. Only water is necessary for life.
B. Only a magnetic field is necessary for life.
C. A suitable combination of factors such as water, atmosphere, proper temperature, gravity and protection from harmful radiation makes Earth favourable for life.
D. Life can exist only on planets made entirely of gases.
Answer: C. A suitable combination of factors such as water, atmosphere, proper temperature, gravity and protection from harmful radiation makes Earth favourable for life.
Explanation: Earth's ability to support life depends on several interconnected conditions rather than a single factor.
Question 1. Why is Earth called a life-sustaining planet?
Answer:
Earth is called a life-sustaining planet because it has suitable conditions for life, such as the right distance from the Sun, liquid water, a suitable temperature, an atmosphere and a protective magnetic field.
Question 2. What is a habitable zone?
Answer:
A habitable zone is the region around a star where the temperature is suitable for water to exist in the liquid state, making conditions favourable for life.
Question 3. Why is liquid water important for life?
Answer:
Liquid water is necessary for many chemical reactions and life processes. It is therefore essential for the survival and functioning of living organisms.
Question 4. Name any two greenhouse gases.
Answer:
Two greenhouse gases are:
- Carbon dioxide
- Methane
Question 5. What is the greenhouse effect?
Answer:
The greenhouse effect is a natural process in which gases in the atmosphere trap heat and help keep Earth warm enough to support life.
Question 6. What is the hydrosphere?
Answer:
The hydrosphere includes all the water present on Earth, such as oceans, rivers, lakes and other water bodies.
Question 7. What is the biosphere?
Answer:
The biosphere is the zone of Earth where living organisms exist.
Question 8. What is the geosphere?
Answer:
The geosphere refers to the solid part of Earth, including rocks, minerals, soil and landforms.
Question 9. What is geodiversity?
Answer:
Geodiversity refers to the variety of natural features such as rocks, soils and landforms found on Earth.
Question 10. How does gravity help in supporting life on Earth?
Answer:
Earth's gravity holds the atmosphere around the planet. The atmosphere provides essential conditions and gases required for sustaining life.
Question 11. What is the role of the ozone layer?
Answer:
The ozone layer protects living organisms by absorbing harmful ultraviolet radiation coming from the Sun.
Question 12. What are cosmic rays?
Answer:
Cosmic rays are high-energy particles that come from outer space.
Question 13. What is solar wind?
Answer:
Solar wind is a stream of particles that originates from the Sun.
Question 14. Why is reproduction important?
Answer:
Reproduction produces new individuals and ensures the survival and continuity of a species from one generation to the next.
Question 15. What is asexual reproduction?
Answer:
Asexual reproduction is a mode of reproduction in which only one parent is involved in producing offspring.
Question 16. What is a gamete?
Answer:
A gamete is a specialised reproductive cell that carries half of the genetic material required for the formation of a new organism.
Question 17. Name the male and female gametes in animals.
Answer:
- Male gamete: Sperm
- Female gamete: Egg or ovum
Question 18. What is fertilisation?
Answer:
Fertilisation is the process in which the male and female gametes fuse to form a zygote.
Question 19. What are the major threats to life on Earth mentioned in the chapter?
Answer:
The major threats are:
- Climate change
- Pollution
- Loss of biodiversity
Question 20. Why is balance in nature important?
Answer:
Balance between living and non-living components helps maintain a stable ecosystem and supports the sustainable continuation of life.