India's #1 AI Tutorworksheet · Science · Chapter 13

CBSE Class 10 Science Chapter 13 Our Environment Worksheet with Answers

Chapter 13 Our Environment is a vital part of the CBSE Class 10 Science curriculum that explores how living organisms interact with their surroundings and each other. This worksheet provides targeted practice on ecosystem components, energy flow through food chains and webs, the critical issue of ozone layer depletion, and sustainable waste management strategies. The questions are carefully designed to match the CBSE board exam pattern and NCERT textbook terminology, ensuring students build confidence and competence.

Your child's private AI tutor — trained on NCERT.

3-day free trial · ₹1 to start · Cancel anytime.

Start 3-day free trial →

Key takeaways

✓This worksheet covers ecosystem, food chain, food web, ozone depletion and waste management as per NCERT Class 10 Science curriculum
✓Contains 25+ questions across MCQs, fill-in-the-blanks, short-answer and long-answer formats mimicking CBSE board exam patterns
✓Difficulty level is moderate with suggested completion time of 90 minutes for effective practice
✓Complete answer key with brief explanations helps students verify their understanding immediately
✓Case-study question develops analytical and application skills required for scoring full marks in board exams
✓Regular practice with this worksheet strengthens conceptual clarity on environmental science topics crucial for Class 10 boards
✓Ideal for revision during exam preparation and identifying weak areas needing focused study

Quick Chapter Recap: Our Environment

Before attempting this worksheet, let us quickly revisit the core concepts from CBSE Class 10 Science Chapter 13. An ecosystem comprises all living organisms (biotic components) and non-living elements (abiotic components) interacting in a specific area. Energy flows unidirectionally through trophic levels—from producers (plants) to primary consumers (herbivores) to secondary and tertiary consumers (carnivores), with decomposers breaking down dead matter. A food chain represents a single linear pathway of energy transfer, while a food web shows multiple interconnected food chains reflecting real ecological complexity. The ozone layer in the stratosphere absorbs harmful ultraviolet radiation; its depletion due to CFCs poses serious health and environmental risks. Waste management involves the 3Rs—Reduce, Reuse, Recycle—alongside proper disposal methods to minimize environmental damage. Biodegradable wastes decompose naturally through microbial action, while non-biodegradable wastes persist and accumulate, causing pollution. Understanding these concepts is essential for answering both theoretical and application-based questions in the CBSE Class 10 board examination.

Ecosystem = Biotic components + Abiotic components interacting together
Trophic levels: Producers → Primary consumers → Secondary consumers → Tertiary consumers
10% law: Only about 10% of energy transfers from one trophic level to the next
Ozone (O₃) layer protects Earth from harmful UV radiation; CFCs cause ozone depletion
Biodegradable wastes: decomposed by microorganisms; Non-biodegradable: persist in environment
Waste management hierarchy: Reduce > Reuse > Recycle > Dispose

Section A: Multiple Choice Questions (1 mark each)

This section contains six multiple-choice questions designed to test your conceptual understanding of fundamental topics in Our Environment. Each question has four options, and you must select the single best answer. MCQs in CBSE Class 10 Science typically assess recall of definitions, understanding of processes, and ability to apply concepts to new situations. Read each question carefully, eliminate obviously incorrect options first, and choose the most accurate answer based on NCERT content. These questions mirror the pattern seen in recent CBSE board examinations and cover ecosystem components, food chains, trophic levels, ozone layer chemistry, and waste classification. Time allocation: 6 minutes for this section. Ensure you attempt all questions even if uncertain, as there is no negative marking in CBSE board exams. Mark your answers clearly and review them if time permits at the end of the worksheet.

Q1. Which of the following groups contains only biodegradable items? (a) Grass, flowers, leather (b) Grass, wood, plastic (c) Fruit peels, cake, lime juice (d) Both (a) and (c)
Q2. The decomposers in an ecosystem (a) convert inorganic material to organic compounds (b) convert organic material to inorganic forms (c) do not breakdown organic compounds (d) are present only in aquatic ecosystems
Q3. In a food chain, the third trophic level is always occupied by (a) Carnivores (b) Herbivores (c) Decomposers (d) Producers
Q4. Ozone layer depletion is caused primarily by (a) Carbon dioxide (b) Chlorofluorocarbons (c) Methane (d) Nitrogen oxides
Q5. An ecosystem must have continuous external source of (a) Energy (b) Food (c) Raw materials (d) All of these
Q6. Which of the following constitutes a food chain? (a) Grass, wheat, mango (b) Grass, goat, human (c) Goat, cow, elephant (d) Grass, fish, goat

Section B: Fill in the Blanks (1 mark each)

Complete each sentence by filling in the blank with the most appropriate term from Chapter 13 Our Environment. This section tests your recall of specific terminology, definitions, and key facts from the NCERT Class 10 Science textbook. Write answers in singular or plural form as grammatically appropriate. Pay attention to scientific spelling—marks may be deducted for incorrect spellings of technical terms like 'chlorofluorocarbons' or 'biodegradable'. These five questions cover the range of topics including trophic levels, energy flow, biological magnification, ozone chemistry, and waste properties. Time allocation: 5 minutes. If you cannot recall a term immediately, move to the next question and return later. Context clues within each sentence often hint at the correct answer. This format frequently appears in CBSE Class 10 board papers and requires precise knowledge of chapter content rather than broad conceptual understanding.

Q7. The phenomenon of accumulation of non-biodegradable pesticides in organisms at successive trophic levels is called __________.
Q8. Producers are also called __________ as they synthesize their own food.
Q9. The amount of energy available decreases as we move from __________ trophic level to __________ trophic level.
Q10. Ozone at ground level is a __________ whereas ozone in the upper atmosphere is __________ for life.
Q11. Materials which can be broken down by biological processes are called __________.

Section C: Match the Following (1 mark each)

Match the items in Column A with the most appropriate items in Column B. Each item in Column A corresponds to exactly one item in Column B. Write your answers as combinations such as 1-d, 2-a, etc. This exercise tests your ability to connect related concepts, identify relationships between organisms and their roles, and associate environmental problems with their causes or solutions. Carefully read all items in both columns before making matches to avoid errors. Some options may seem similar, but only one pairing is scientifically accurate according to NCERT Class 10 Science content. This format enhances understanding of ecological relationships and environmental science terminology. Time allocation: 5 minutes. Matching questions assess deeper comprehension than simple recall and are common in CBSE practical and theory examinations alike. Cross-check your answers to ensure no item is used twice and all items are paired appropriately.

Column A: (1) Producers (2) Primary consumers (3) Secondary consumers (4) Decomposers (5) Ozone layer protection
Column B: (a) Herbivores (b) Break down complex organic matter (c) Small carnivores (d) Autotrophs (e) Montreal Protocol

Section D: Short Answer Questions (2 marks each)

Answer each of the following questions in approximately 30-40 words. Short-answer questions in CBSE Class 10 Science examinations typically carry 2 marks and require you to demonstrate clear understanding of concepts with relevant examples or brief explanations. Structure your answer in 2-3 concise sentences, using scientific terminology from the NCERT textbook. Avoid unnecessary elaboration as you have limited space and time. Focus on directly addressing what the question asks—define terms, explain processes, give examples, or differentiate concepts as required. These five questions span the entire chapter content including ecosystem interactions, energy pyramids, environmental protection measures, and waste management strategies. Time allocation: 15 minutes (3 minutes per question). Use proper scientific language and avoid vague statements. Where appropriate, include examples to strengthen your answer and demonstrate application of knowledge. Clarity and accuracy matter more than length in short-answer responses.

Q12. What is the role of decomposers in an ecosystem? Name two decomposers.
Q13. Explain why the energy flow in an ecosystem is unidirectional.
Q14. What are the harmful effects of ozone depletion?
Q15. Distinguish between biodegradable and non-biodegradable wastes with one example each.
Q16. What is meant by biological magnification? Why is it a cause for concern?

Section E: Long Answer Questions (3-5 marks each)

Answer the following questions in detail, allocating approximately 80-100 words per answer. Long-answer questions in the CBSE Class 10 Science board exam assess your ability to explain concepts comprehensively, draw diagrams where relevant, provide multiple examples, and demonstrate higher-order thinking skills. Structure your answers logically with an introductory statement, main explanation with supporting points, and a brief conclusion if appropriate. These three questions include both standard descriptive questions and HOTS (Higher Order Thinking Skills) questions that require application, analysis, and evaluation rather than mere recall. Use paragraphs or numbered points for clarity. Include diagrams for food chains or webs if asked. Time allocation: 25 minutes (approximately 8 minutes per question). Question 17 carries 3 marks, while Questions 18 and 19 carry 5 marks each. Plan your answer mentally before writing to ensure all required points are covered. HOTS questions may present unfamiliar scenarios—apply chapter concepts creatively to address them systematically and logically.

Q17. Construct a terrestrial food chain with four trophic levels. Why do food chains generally consist of only three or four steps? (3 marks)
Q18. What is ozone? How is it formed in the upper atmosphere? Why is ozone layer depletion a cause of concern for us? List any two measures to prevent ozone depletion. (5 marks)
Q19. (HOTS) Suggest any four activities in daily life which are eco-friendly. Explain how the habit of reusing materials helps in reducing environmental pollution. (5 marks)

Section F: Case Study Question (4 marks)

Read the following case carefully and answer the questions that follow. Case-study questions have become an integral part of the CBSE Class 10 Science examination pattern since 2020-21. These questions assess your ability to apply theoretical knowledge to real-world situations, analyze data, interpret scenarios, and draw conclusions. The case study presented here relates to waste management practices in an Indian city, connecting classroom learning with practical environmental challenges faced daily. Read the passage thoroughly, identify key information, and then attempt each sub-question carefully. Each sub-question typically carries 1 mark and may be MCQ format or very short answer type. Time allocation: 10 minutes. This question format tests comprehension, analytical ability, and application skills—all crucial for scoring well in CBSE boards. Use information from both the case study and your chapter knowledge to arrive at accurate answers. Such integrated questions reward students who understand concepts deeply rather than those who memorize isolated facts without context or application ability.

Case Study: A municipal corporation in a Tier-2 Indian city generates approximately 500 tonnes of waste daily. About 60% is biodegradable kitchen and garden waste, 25% is recyclable materials like paper, plastic, and metal, and 15% is non-recyclable waste. The city plans to set up a composting facility for biodegradable waste and a material recovery facility for recyclables. Currently, most waste goes to open dumping grounds, causing soil and water pollution.
Q20(i). What percentage of the total waste can be processed through composting? (a) 25% (b) 60% (c) 15% (d) 85%
Q21(ii). Which microorganisms are primarily responsible for breaking down biodegradable waste in composting?
Q22(iii). Open dumping of non-biodegradable waste is harmful because it (a) releases nutrients into soil (b) provides food for decomposers (c) accumulates and pollutes environment (d) increases soil fertility
Q23(iv). Suggest one way households can contribute to reducing the burden on municipal waste management.

Complete Answer Key with Explanations

This section provides correct answers to all questions along with brief explanations to help you understand why each answer is correct. Use this answer key only after attempting all questions yourself. Self-assessment is crucial for identifying knowledge gaps and strengthening weak areas before the CBSE Class 10 board examination. For MCQs and fill-in-the-blanks, the correct option or term is provided with rationale. For short and long answers, model responses are given highlighting key points that should be included for full marks. Compare your answers with these model responses, noting any missing points or incorrect explanations. If you scored below seventy percent on this worksheet, revisit the NCERT Class 10 Science textbook chapter thoroughly and practice additional questions. The case-study answers demonstrate how to extract relevant information and apply chapter concepts to practical scenarios. Regular practice with such worksheets, combined with thorough conceptual study, ensures strong performance in board examinations. For personalized doubt-clearing and step-by-step solutions to difficult questions, students can explore CBSETUTOR.ai, which offers 24×7 AI tutoring with photo-upload problem solving at just ₹999 per month with a 3-day free trial for all classes 6-12.

Answers: Section A (MCQs)

Q1. (d) Both (a) and (c). Explanation: Biodegradable materials are those that can be broken down by biological processes. Grass, flowers, leather, fruit peels, cake, and lime juice are all organic materials that decompose naturally. Plastic in option (b) is non-biodegradable, making that option incorrect. Q2. (b) convert organic material to inorganic forms. Explanation: Decomposers like bacteria and fungi break down complex organic compounds from dead organisms into simpler inorganic substances such as CO₂, water, and nutrients, which are recycled in the ecosystem. Q3. (a) Carnivores. Explanation: In a food chain, the first trophic level has producers, second has herbivores (primary consumers), and third has carnivores (secondary consumers) that feed on herbivores. Q4. (b) Chlorofluorocarbons. Explanation: CFCs released from refrigerants and aerosol sprays rise to the stratosphere where they break down ozone molecules, causing ozone layer depletion. Q5. (a) Energy. Explanation: Energy flows unidirectionally through an ecosystem and is lost at each trophic level as heat, so continuous input from the sun is essential. Q6. (b) Grass, goat, human. Explanation: This represents a valid food chain where grass (producer) is eaten by goat (herbivore/primary consumer) which is consumed by human (omnivore/secondary consumer).

Answers: Sections B, C, D, E, and F

Section B Answers: Q7. biological magnification (or biomagnification). Q8. autotrophs. Q9. lower, higher. Q10. pollutant, beneficial (or protective). Q11. biodegradable. Section C Answers: 1-d (Producers are Autotrophs), 2-a (Primary consumers are Herbivores), 3-c (Secondary consumers are Small carnivores), 4-b (Decomposers break down complex organic matter), 5-e (Ozone layer protection via Montreal Protocol). Section D Answers: Q12. Decomposers break down dead organic matter into simpler inorganic substances, recycling nutrients back to the environment. Examples: bacteria and fungi. Q13. Energy captured by producers flows unidirectionally to herbivores, then carnivores, and is lost as heat at each level. It cannot flow backwards, making the process unidirectional. Q14. Ozone depletion allows more UV radiation to reach Earth, causing skin cancer, cataracts in humans, and damage to plants and aquatic ecosystems. Q15. Biodegradable wastes decompose naturally (e.g., vegetable peels). Non-biodegradable wastes do not decompose and persist in the environment (e.g., plastic bags). Q16. Biological magnification is the accumulation of non-biodegradable substances like pesticides at successive trophic levels. It is concerning because top carnivores accumulate harmful concentrations, affecting health and reproduction. Section E Answers: Q17. Example chain: Grass → Grasshopper → Frog → Snake. Food chains are limited to 3-4 steps because only 10% energy transfers to the next level; after 4 steps, insufficient energy remains to support another level. Q18. Ozone (O₃) is a molecule with three oxygen atoms. UV radiation splits O₂ into oxygen atoms which combine with O₂ to form O₃. Depletion causes increased UV exposure leading to skin cancer, cataracts, reduced immunity, and harm to phytoplankton. Measures: ban CFCs, use eco-friendly refrigerants, implement Montreal Protocol. Q19. Eco-friendly activities: using cloth bags, composting kitchen waste, using public transport, conserving water and electricity. Reusing reduces demand for new materials, saving energy and resources used in manufacturing, thus reducing pollution and waste generation. Section F Answers: Q20(i). (b) 60%. Q21(ii). Bacteria and fungi. Q22(iii). (c) accumulates and pollutes environment. Q23(iv). Segregate waste at source into biodegradable and non-biodegradable categories (or any reasonable suggestion like composting at home, reducing plastic use, etc.).

Frequently asked questions

What is the difficulty level and time limit for this CBSE Class 10 Science Chapter 13 worksheet?+

This worksheet is of moderate difficulty, aligned with CBSE board exam standards. The suggested time to complete all sections is 90 minutes. This allows adequate time for reading, thinking, and writing answers carefully while simulating exam conditions.

How many marks is this Our Environment worksheet worth in total?+

The worksheet contains questions totaling approximately 35-40 marks: 6 MCQs (6 marks), 5 fill-in-the-blanks (5 marks), 5 matching items (5 marks), 5 short answers (10 marks), 3 long answers (13 marks), and 1 case study (4 marks). This comprehensive coverage helps thorough exam preparation.

Does this worksheet cover all topics from NCERT Class 10 Science Chapter 13?+

Yes, this worksheet comprehensively covers all major topics from Chapter 13 Our Environment including ecosystem components, food chains and webs, trophic levels, energy flow, ozone layer depletion, biological magnification, and waste management—exactly as prescribed in the NCERT syllabus.

Why are food chains usually limited to three or four trophic levels?+

Food chains are limited because only about 10% of energy transfers from one trophic level to the next; the remaining 90% is lost as heat during metabolic processes. After 3-4 transfers, insufficient energy remains to support another trophic level, limiting chain length naturally.

What is biological magnification and why is it dangerous?+

Biological magnification is the progressive accumulation of non-biodegradable substances like pesticides (DDT) at successive trophic levels. It is dangerous because top carnivores accumulate harmful concentrations of these toxins, causing health problems, reproductive failure, and even death, as famously documented in birds of prey.

How do CFCs cause ozone layer depletion?+

Chlorofluorocarbons (CFCs) rise to the stratosphere where intense UV radiation breaks them down, releasing chlorine atoms. Each chlorine atom catalytically destroys thousands of ozone molecules by converting O₃ to O₂, thus depleting the protective ozone layer that shields Earth from harmful ultraviolet radiation.

What is the difference between biodegradable and non-biodegradable waste?+

Biodegradable wastes like food scraps, paper, and cotton are broken down naturally by microorganisms into simpler substances. Non-biodegradable wastes like plastics, metals, and glass do not decompose naturally, persist in the environment for years, accumulate, and cause pollution requiring special disposal methods.

How should students use the answer key provided in this worksheet?+

Students should attempt all questions independently first, then check answers using the answer key. Compare your responses with model answers, identify gaps in understanding, and note correct terminologies. If your score is below 70%, revisit NCERT Chapter 13 thoroughly before practicing additional questions.

Are case-study questions important for CBSE Class 10 Science board exams?+

Yes, case-study questions have been a regular feature in CBSE Class 10 Science papers since 2020-21. They carry 4 marks and test your ability to apply theoretical knowledge to real-world situations, analyze data, and draw conclusions—skills crucial for scoring well in board examinations.

Where can I get additional practice and doubt-solving for Class 10 Science Chapter 13?+

For personalized learning, students can use CBSETUTOR.ai, which provides 24×7 AI-powered tutoring with instant solutions through photo upload for just ₹999 per month covering all classes 6-12. A 3-day free trial is available to help students experience interactive, on-demand learning and doubt-clearing support anytime.

Related resources

Important Questions: CBSE Class 10 Science Chapter 13 Our Environment Class 10 Science Chapter 13 Our Environment — Formulas & Key Points Important Questions: CBSE Class 10 Science Chapter 12 Magnetic Effects of Electric Current CBSE Class 10 Science Chapter 12 Magnetic Effects of Electric Current Worksheet with Answers AI Tutor for Class 10: The Smart Alternative to Tuition AI Tutor for Class 10 Maths: Learn Faster with Instant Help Online Class 9 Science Tutor in Mumbai – 24/7 CBSE-Aligned AI Coaching CBSE Class 9 Mathematics Chapter 1 Number Systems Worksheet with Answers

Keep learning — related guides

Class 10Science

Class 10 Science Chapter 11 Electricity — Formulas & Key Points

Class 10Science

CBSE Class 10 Science Chapter 11 Electricity Worksheet with Answers

Class 10Science

Class 10 Science Chapter 13 Our Environment — Formulas & Key Points

Class 10Science

Class 10 Science Chapter 12 Magnetic Effects of Electric Current — Formulas & Key Points

Class 10Science

Important Questions: CBSE Class 10 Science Chapter 13 Our Environment

Class 10Science

Class 10 Science Chapter 10 The Human Eye and the Colourful World — Formulas & Key Points

Ready to give your Class 10 child the tutor that never sleeps?

CBSETUTOR.ai covers every chapter in the Class 10 NCERT syllabus — Maths, Science, Social Science, English, Hindi and more. 24×7. Patient. Unlimited. 3-day free trial.

Start your child's 3-day free trial →