Class 8 Science - WEST-BENGAL
Our Home: Earth a Unique Life-Sustaining Planet
This chapter explores why Earth is the only known planet in our solar system that supports life. Students learn about the Goldilocks zone, the unique combination of distance from the Sun, presence of liquid water, oxygen-rich atmosphere, and a suitable temperature range that makes existence possible. For West Bengal (WBBSE) board exams, this chapter is crucial as it builds foundational knowledge about Earth's spheres (lithosphere, hydrosphere, atmosphere, and biosphere) and our responsibility to protect the environment against global warming and pollution, frequently appearing in both objective and descriptive board questions.
Start Learning FreeKey Concepts
Habitable Zone (Goldilocks Zone)
The orbital region around a star where conditions are neither too hot nor too cold for liquid water to exist on a planet's surface.
Atmosphere and Greenhouse Effect
Earth's blanket of gases traps just enough heat from the Sun to keep the planet warm and shield living beings from harmful UV rays.
The Hydrosphere
About 71 percent of Earth's surface is covered with water, which is essential for all known biochemical reactions and forms of life.
The Biosphere
The narrow zone of contact between land, water, and air where life exists, creating a complex web of interdependent organisms.
Ozone Layer Protection
A layer in the stratosphere containing high concentrations of ozone that absorbs most of the Sun's harmful ultraviolet radiation.
Important Formulas
Board Exam Info
In West Bengal (WBBSE) Class 8 Science examinations, this chapter typically carries around 4 to 7 marks. Questions usually include multiple-choice questions (MCQs), short answer questions about Earth's unique conditions, and descriptive questions explaining the role of the atmosphere or hydrosphere in sustaining life.
Frequently Asked Questions
Why is Earth called a unique planet?
Earth is called unique because it is the only planet in the solar system with liquid water, breathable oxygen, and a temperature range suitable for life.
What would happen if Earth was closer to the Sun like Venus?
If Earth were closer to the Sun, temperatures would be extremely high, causing all surface water to evaporate and making life impossible due to a runaway greenhouse effect.
What is the role of the ozone layer in sustaining life on Earth?
The ozone layer absorbs harmful ultraviolet (UV) radiation from the Sun, preventing it from reaching the Earth's surface and causing skin cancer or cellular damage to living organisms.
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