Our Environment – Short Answer Type Questions
CBSE Class 10 Biology — Chapter 13: Our Environment — 50 Short Answer Questions & Answers
Class: CBSE Class 10
Subject: Science — Biology
Chapter: Chapter 13 — Our Environment
CBSE Board Examinations
Systematic order: Syllabus → Learning objectives → Topic-wise Q&A → Exam practice
Instructions: 50 topic-wise short answer questions with clear, exam-focused answers aligned to NCERT Class 10 Biology — Chapter 13: Our Environment. Use these for revision, classroom practice, and board exam preparation.
Basics & Ecosystem (Q1–10)
Q1.What is an ecosystem?
A: An ecosystem is a functional unit consisting of a community of organisms interacting with each other and with their physical environment.
Q2.Differentiate between biotic and abiotic components.
A: Biotic components are living (plants, animals, microbes); abiotic components are non-living (sunlight, water, soil, temperature).
Q3.What is meant by a food chain?
A: A food chain is a linear sequence of organisms through which energy and nutrients flow from producers to consumers and decomposers.
Q4.Define producer, consumer and decomposer with one example each.
A: Producer: green plants (e.g., grass). Consumer: herbivore/carnivore (e.g., deer, tiger). Decomposer: fungi/bacteria (e.g., Rhizopus).
Q5.What is a habitat?
A: Habitat is the natural place where an organism lives and obtains its requirements (food, shelter, mates).
Q6.Explain the term 'community' in ecology.
A: A community is the assemblage of different populations of species living and interacting in a common area.
Q7.What is an ecological niche?
A: An ecological niche is the role and position a species has in its ecosystem including its habitat, feeding relationships and behavior.
Q8.Why are decomposers important?
A: Decomposers break down dead organic matter into inorganic nutrients, recycling materials back to the soil for producers to use.
Q9.Define biodiversity briefly.
A: Biodiversity is the variety of life at genetic, species and ecosystem levels in a region or on Earth.
Q10.What is biosphere?
A: Biosphere is the global zone where life exists — parts of Earth’s land, water and atmosphere inhabited by living organisms.
Food Chains, Food Webs & Ecological Pyramids (Q11–20)
Q11.What is a food web?
A: A food web is a network of interconnected food chains showing multiple feeding relationships in an ecosystem.
Q12.Give an example of a simple terrestrial food chain.
A: Grass → Grasshopper → Frog → Snake → Eagle.
Q13.Define trophic level.
A: A trophic level is a feeding step in a food chain (producers = 1st trophic level, primary consumers = 2nd, etc.).
Q14.What is meant by pyramid of numbers?
A: Pyramid of numbers shows the number of organisms at each trophic level; it can be upright or inverted depending on ecosystem.
Q15.Why is the pyramid of energy always upright?
A: Because energy decreases at each successive trophic level due to losses (heat, respiration), so less energy is available up the chain.
Q16.What is biomass?
A: Biomass is the total mass of living organisms (usually dry weight) at a given trophic level or ecosystem.
Q17.Explain biomagnification.
A: Biomagnification is the progressive increase in concentration of toxic substances (e.g., DDT) in organisms at higher trophic levels.
Q18.Why are food chains usually short?
A: Because energy transfer efficiency is low (~10% to next level), limiting the number of sustainable trophic levels.
Q19.What is detritus food chain?
A: A detritus food chain begins with dead organic matter (detritus) and is driven by decomposers and detritivores.
Q20.Give one difference between grazing and detritus food chains.
A: Grazing chains begin with live producers eaten by herbivores; detritus chains begin with dead organic matter processed by decomposers.
Energy Flow & Nutrient Cycles (Q21–30)
Q21.What is the primary source of energy for most ecosystems?
A: The Sun is the primary source of energy for most ecosystems via photosynthesis.
Q22.State the 10% rule in ecology.
A: Approximately 10% of the energy at one trophic level is transferred to the next; the rest is lost as heat and waste.
Q23.List two processes in the carbon cycle.
A: Photosynthesis (CO₂ → organic carbon) and respiration (organic carbon → CO₂) are two key processes.
Q24.What role do decomposers play in the nitrogen cycle?
A: Decomposers break down organic nitrogen into ammonium, returning nitrogen to the soil for further transformations.
Q25.Name two nitrogen-transforming processes carried out by bacteria.
A: Nitrogen fixation (N₂ → NH₃) and nitrification (NH₄⁺ → NO₂⁻ → NO₃⁻); denitrification returns NO₃⁻ to N₂.
Q26.Why is nutrient cycling important?
A: Nutrient cycling recycles essential elements so they remain available for organisms and sustain ecosystem productivity.
Q27.What is eutrophication?
A: Eutrophication is nutrient enrichment (usually N and P) of water bodies causing algal blooms and oxygen depletion.
Q28.How do human activities accelerate the carbon cycle?
A: Burning fossil fuels, deforestation and land-use changes release stored carbon as CO₂, increasing atmospheric levels.
Q29.What is nitrogen fixation and give one example?
A: Nitrogen fixation converts atmospheric N₂ into usable forms (NH₃); e.g., Rhizobium bacteria in legume root nodules fix nitrogen.
Q30.What is the effect of excessive fertilizer use on water bodies?
A: Runoff of fertilizers causes eutrophication, algal blooms and subsequent oxygen depletion harming aquatic life.
Biodiversity & Conservation (Q31–40)
Q31.Why is biodiversity important?
A: Biodiversity provides ecosystem services, genetic resources for food and medicine, and enhances ecosystem stability and resilience.
Q32.Name two causes of biodiversity loss.
A: Habitat destruction and over-exploitation are two major causes; invasive species and pollution also contribute.
Q33.What is in-situ conservation? Give one example.
A: In-situ conservation protects species in their natural habitats (e.g., national parks, wildlife sanctuaries).
Q34.What is ex-situ conservation? Give one example.
A: Ex-situ conservation involves protecting species outside their natural habitat (e.g., zoos, botanical gardens, seed banks).
Q35.How do wildlife corridors help conservation?
A: Corridors connect fragmented habitats, allowing movement, migration and gene flow between populations.
Q36.What is the role of community participation in conservation?
A: Local communities contribute to sustainable resource use, protection of habitats and awareness—vital for long-term conservation success.
Q37.Give one example of a legal measure for conservation.
A: Laws banning hunting of endangered species or regulations establishing protected areas (e.g., Wildlife Protection Act).
Q38.What is afforestation and why is it important?
A: Afforestation is planting trees on non-forested lands; it helps restore habitats, sequester carbon and prevent soil erosion.
Q39.Name one international agreement for environment protection.
A: The Montreal Protocol (to protect the ozone layer) or the Convention on Biological Diversity (CBD).
Q40.What is a seed bank and its purpose?
A: A seed bank stores seeds of plants under controlled conditions to preserve genetic diversity and restore species if needed.
Pollution & Waste Management (Q41–50)
Q41.Define pollution.
A: Pollution is the introduction of harmful substances or energy into the environment that causes adverse effects to organisms and ecosystems.
Q42.List two major air pollutants.
A: Particulate matter (PM₂.₅/PM₁₀) and sulphur dioxide (SO₂); nitrogen oxides (NOx) and carbon monoxide (CO) are others.
Q43.What causes acid rain?
A: Emissions of SO₂ and NOx react with water in the atmosphere forming acidic compounds that fall as acid rain.
Q44.Explain eutrophication in brief.
A: Eutrophication is nutrient enrichment of water bodies (often from fertilizers) causing algal blooms and oxygen depletion.
Q45.Give two sources of water pollution.
A: Industrial effluents and untreated sewage; agricultural runoff and oil spills are additional sources.
Q46.What is biomagnification and give one consequence?
A: Biomagnification is accumulation of toxins up the food chain; consequence: top predators may suffer reproductive failure or mortality.
Q47.Differentiate biodegradable and non-biodegradable wastes with an example each.
A: Biodegradable waste (e.g., food scraps) can be decomposed by microbes; non-biodegradable (e.g., plastic) resists decomposition and accumulates.
Q48.What is sanitary landfill?
A: A sanitary landfill is an engineered site for safe disposal of solid waste with layers, lining and measures to control pollution.
Q49.List the '3 Rs' of waste management.
A: Reduce (minimise waste), Reuse (use items multiple times) and Recycle (convert waste into new products).
Q50.Mention one student-level action to reduce pollution.
A: Use public transport or cycle, reduce single-use plastics, participate in tree planting and segregation of waste at source.