Class 10 Science - CBSE
Our Environment
The Class 10 CBSE Science chapter 'Our Environment' explores how human activities and natural phenomena interact to shape the surroundings. Students will learn about the structure of ecosystems, biotic and abiotic components, food chains, and food webs. A major focus is placed on biological magnification, energy flow through trophic levels following the 10 percent law, and environmental concerns such as ozone layer depletion and improper waste disposal. This chapter carries significant weight in board exams, testing both conceptual understanding and diagram-based questions regarding energy flow and ecological pyramids.
Start Learning FreeKey Concepts
Ecosystem
A self-sustaining functional unit consisting of all living organisms (biotic components) interacting with each other and with the non-living physical environment (abiotic components).
Trophic Levels and Food Chain
Specific steps in a food chain where energy is transferred, moving from producers to primary, secondary, and tertiary consumers.
Ten Percent Law
Only 10 percent of the energy entering a particular trophic level is available for transfer to the next trophic level, limiting food chains to 4 or 5 steps.
Biological Magnification
The progressive accumulation of harmful, non-biodegradable chemicals like pesticides at successive trophic levels in a food chain.
Ozone Layer Depletion
The thinning of the protective ozone shield in the stratosphere primarily caused by synthetic chemicals like chlorofluorocarbons (CFCs).
Biodegradable vs Non-Biodegradable Waste
Biodegradable wastes are broken down by biological processes, whereas non-biodegradable wastes remain in the environment for a long time, causing pollution.
Important Formulas
Board Exam Info
In the CBSE Class 10 Science board examination, this chapter typically carries around 3 to 4 marks as part of the 'Natural Resources and Environment' unit. Common question types include direct definitions, calculating energy transfer using the 10 percent law, explaining ozone depletion, and differentiating between biodegradable and non-biodegradable wastes.
Frequently Asked Questions
Why is the flow of energy in an ecosystem always unidirectional?
Energy lost as heat to the environment from a trophic level cannot be reused by plants, and energy does not flow backward from higher trophic levels to producers.
What is biological magnification and why does it affect top carnivores the most?
It is the accumulation of non-biodegradable toxins. Top carnivores receive the highest concentration because they are at the top of the food chain, ingesting toxins accumulated from all lower levels.
How does the ozone layer protect life on Earth?
The ozone layer absorbs harmful ultraviolet (UV) radiations coming from the Sun, preventing them from reaching the Earth's surface where they can cause skin cancer and eye damage.
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