NCERT Solutions for Class 10 Science Chapter 13 Our Environment
NCERT Solutions for Class 10 Science Chapter 13 Our Environment covers ecosystems, biotic and abiotic components, food chains and webs, energy flow and the 10% law, biological magnification, ozone layer depletion, and waste management techniques.
Overview of Topics & Subtopics (Click to Jump)
1. Ecosystem and Its Components
Short Note:
• Ecosystem: A self-sustaining structural and functional unit of nature consisting of living organisms interacting with each other and their non-living physical environment.
• Biotic Components: Producers (autotrophs), Consumers (herbivores, carnivores, omnivores, parasites), and Decomposers (bacteria and fungi).
• Abiotic Components: Non-living factors such as temperature, light, water, soil, minerals, and air.
• Types: Natural ecosystems (forest, lake, ocean) and Artificial/Man-made ecosystems (crop fields, garden, aquarium).
2. Food Chains and Food Webs
Short Note:
• Food Chain: A linear sequence of organisms where energy and nutrients pass from one organism to another as one eats another (e.g., Grass → Deer → Lion).
• Food Web: A complex network of interconnected food chains operating naturally within an ecosystem, reflecting real feeding relationships.
3. Trophic Levels & Energy Transfer (10% Law)
Short Note:
• Trophic Levels: The distinct steps or levels in a food chain where transfer of food energy takes place (Producers → Primary Consumers → Secondary Consumers → Tertiary Consumers).
• 10% Law (Lindeman's Law): Only about 10% of the energy available at a particular trophic level is transferred to the next higher level. The remaining 90% is lost as heat to the environment during metabolism and respiration.
• Flow of energy in an ecosystem is always unidirectional.
4. Biological Magnification
Short Note:
• Biological Magnification (Biomagnification): The progressive accumulation of non-biodegradable harmful chemicals (like pesticides, DDT) at successive higher trophic levels in a food chain.
• Human beings occupy the topmost level in most food chains, resulting in maximum chemical concentration inside human bodies.
5. Environmental Problems & Waste Management
Short Note:
• Ozone Layer Depletion: Ozone (O3) protects Earth from harmful ultraviolet (UV) radiation. Depletion is caused by Chlorofluorocarbons (CFCs) used in refrigerators and fire extinguishers.
• Biodegradable Waste: Waste materials that can be broken down naturally by microorganisms (e.g., vegetable peels, paper, cotton).
• Non-Biodegradable Waste: Materials that cannot be decomposed by natural biological processes (e.g., plastics, polythene bags, metals, synthetic fibers).
Intext Questions - Page Number: 257
Example of a terrestrial food chain:
Grass → Grasshopper → Frog → Snake
• First Trophic Level (Producers): Grass
• Second Trophic Level (Primary Consumers): Grasshopper
• Third Trophic Level (Secondary Consumers): Frog
• Fourth Trophic Level (Tertiary Consumers): Snake
Intext Questions - Page Number: 261
1. They persist in soil and water bodies for long periods, causing environmental pollution and choking drainage systems.
2. Toxic non-biodegradable chemicals (like DDT) enter food chains and undergo biomagnification, threatening top-level species including humans.
Textbook Chapter End Exercise Questions
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass
Correct Answer: Options (a), (c), and (d) contain only biodegradable items.
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Correct Answer: (b) Grass, goat and human.
(a) Carrying cloth-bags to put purchases in while shopping
(b) Switching off unnecessary lights and fans
(c) Walking to school instead of getting your mother to drop you on her scooter
(d) All of the above
Correct Answer: (d) All of the above.
1. Segregation and Recycling: Separating biodegradable and non-biodegradable wastes at the source and recycling plastic, glass, and metal items.
2. Composting: Converting kitchen wet waste, vegetable peels, and fallen leaves into organic manure using compost pits.
Read More & Chapter Resources
These short notes are designed for quick revision. Read the main points once, then use the related material below to practise the same chapter. Revising a concept and checking it with questions can make your preparation more focused.