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Important Questions: CBSE Class 7 Science Chapter 6 Respiration in Organisms

Respiration in Organisms is a core chapter in CBSE Class 7 Science, bridging everyday observations — why we breathe, why dough rises, why fish need water — with cellular biology. Students often confuse breathing with respiration or struggle to explain anaerobic respiration in exams. This question bank organizes 18 important exam-style questions by marks, provides model answers using NCERT terminology, and highlights common pitfalls to help Class 7 students score confidently in school tests and Olympiads alike.

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Key takeaways

✓Chapter 6 Respiration in Organisms typically carries 4-6 marks in CBSE Class 7 terminal exams with 2-3 questions across difficulty levels
✓Cellular respiration, aerobic vs anaerobic respiration, and breathing mechanisms are the three highest-weightage topics for exam questions
✓CBSE frequently asks diagram-based questions on human respiratory system, diaphragm movement, and stomata in leaves
✓Understanding the difference between breathing and respiration is crucial — mixing these terms costs many students 1-2 marks in exams
✓5-mark questions often come as case studies involving real-life scenarios like muscle cramps during exercise or yeast fermentation
✓Practicing MCQs on respiration in plants, insects, earthworms, and fish helps secure quick 1-mark gains in competitive exams
✓Model answers provided here use exact NCERT language, ensuring maximum marks under current CBSE marking schemes

Chapter Overview and Marks Weightage in CBSE Exams

Chapter 6 Respiration in Organisms introduces students to the cellular process that releases energy from food. It explains how breathing (inhalation and exhalation) is different from cellular respiration (breakdown of glucose in cells). The chapter covers aerobic respiration (with oxygen) and anaerobic respiration (without oxygen), breathing mechanisms in humans, and how plants, insects, earthworms, and fish respire. In CBSE Class 7 terminal exams, this chapter typically contributes 4-6 marks through 2-3 questions. School-level periodic tests allocate 5-8 marks, often including a diagram-based question on the human respiratory system or stomata. Competitive exams like NSTSE and NSO frequently test respiration in different organisms and the difference between aerobic and anaerobic processes. Understanding the definitions verbatim from NCERT and practicing diagram labelling are high-priority strategies.

Expected marks: 4-6 in term exams, 5-8 in periodic tests
Common question types: MCQs on organism-specific respiration, 2-mark definition pairs (breathing vs respiration), 3-mark diagram labelling, 5-mark case-based on exercise or fermentation
High-weightage topics: cellular respiration process, aerobic vs anaerobic, human breathing mechanism (diaphragm role), respiration in plants (stomata, lenticels)
Diagram must-knows: human respiratory system, diaphragm position during inhalation/exhalation, stomata structure

1-Mark Questions: MCQs and Very Short Answer (VSA)

One-mark questions test recall and quick application. CBSE loves MCQs on which organism uses which breathing structure (gills, spiracles, lungs, skin) and true/false on respiration facts. VSA questions ask for single-word or one-sentence answers. Students must write exact NCERT terms — for example, 'stomata' not 'pores in leaves' — to secure full marks. Below are six representative 1-mark questions with model answers that mirror actual exam language and difficulty.

2-Mark Questions with Model Answers

Two-mark questions require brief explanations, typically two to three sentences or two distinct points. CBSE examiners look for clarity, correct terminology, and completeness. Common formats include 'Differentiate between X and Y' or 'Why does X happen?' Students lose marks when they write only one point or use vague language. Each question below is followed by a model answer structured to earn full marks under standard CBSE marking schemes used across schools in India.

3-Mark Questions with Detailed Answers

Three-mark questions demand structured explanations, often three clear points or a short paragraph with examples. CBSE values logical flow and use of scientific terms. Diagram-based questions also fall here: 'Draw and label the human respiratory system' or 'Show diaphragm position during inhalation and exhalation.' Students should practice writing answers in bullet points to ensure each mark-worthy point is visible to the examiner. Below are four 3-mark questions representative of term exam papers and competitive school assessments across CBSE schools in metros and Tier-2 cities alike.

5-Mark Questions and Case-Based Problems

Five-mark questions are the foundation of CBSE Class 7 Science exams. They test deep understanding, ability to connect concepts, and application to real-life situations. Case-based questions present a scenario — a student running a race, bread dough rising in a warm kitchen, a fish tank without a pump — and ask students to explain the science. Examiners award marks for identifying the type of respiration, naming products, explaining the process, and giving reasons. Writing in clear sub-points (a, b, c) and using NCERT vocabulary (like 'cellular respiration,' 'aerobic,' 'anaerobic,' 'lactic acid,' 'spiracles') maximizes scores. Below are three high-quality 5-mark questions with fully worked model answers.

How CBSE Frames Questions from This Chapter

Understanding the question patterns helps students prepare strategically. CBSE Class 7 Science papers and school term exams follow predictable frameworks for Respiration in Organisms. One-mark questions are direct recall — 'Name the respiratory organ of fish' or 'What is the end product of aerobic respiration?' Two-mark questions ask for differences or short explanations, often starting with 'Differentiate between' or 'Why does.' Three-mark questions demand structured explanations or diagram labelling: 'Draw and label the human respiratory system,' 'Explain the breathing mechanism,' or 'Describe respiration in plants.' Five-mark questions are application-based, presenting everyday scenarios like exercise, fermentation, or aquatic life, then asking students to identify the type of respiration, explain the process, and name products. CBSE also loves to test the difference between breathing and respiration — a conceptual pair that trips up many students. Diagram questions appear in 60-70 percent of Class 7 Science papers; practicing neat, labeled diagrams of lungs, diaphragm positions, and stomata is non-negotiable. Examiners reward answers that use exact NCERT terms and show clear logical structure.

1-mark: direct recall (organ names, product names, true/false on aerobic vs anaerobic)
2-mark: differences (breathing vs respiration, aerobic vs anaerobic), short 'why' explanations
3-mark: structured explanations (stomata function, diaphragm role, fish gills), simple diagrams
5-mark: case studies (exercise, bread-making, aquatic respiration), complete process descriptions with examples
Diagram weightage: human respiratory system (3 marks), diaphragm during inhalation/exhalation (2-3 marks), stomata cross-section (2 marks)

Common Mistakes Students Make in Chapter 6 Exams

Even well-prepared students lose marks due to recurring errors. The most common mistake is confusing breathing with respiration. Breathing is the mechanical act of inhaling and exhaling; respiration is the cellular biochemical process. Writing 'respiration occurs in lungs' instead of 'breathing occurs in lungs; respiration occurs in cells' costs marks. Another frequent error is stating that anaerobic respiration in muscles produces alcohol — it produces lactic acid; yeast produces alcohol. Students often forget to mention both products of aerobic respiration (carbon dioxide and water) or write vague answers like 'energy is released' without naming ATP. In diagram questions, missing labels (like bronchi, alveoli, diaphragm) or incorrect positions lose 1-2 marks. Many students write 'pores' instead of 'stomata' or 'air pipes' instead of 'tracheae,' which examiners may not accept under strict marking. Time management is also an issue — spending too long on a 5-mark question leaves no time to check 1-mark and 2-mark answers. Finally, not reading the question carefully leads to answers that are correct in general but do not address what was asked. For instance, if the question asks 'Explain anaerobic respiration in yeast,' writing about muscle cramps is irrelevant.

Mixing breathing and respiration definitions — costs 1-2 marks in 2-mark and 3-mark questions
Writing 'alcohol' for anaerobic respiration in muscles (correct answer: lactic acid)
Incomplete answers: naming only CO₂ without water for aerobic respiration, or writing 'energy' without specifying the comparison between aerobic (more) and anaerobic (less)
Diagram errors: missing labels, wrong positions, unlabelled arrows for air flow
Using informal terms ('air holes' instead of 'stomata', 'breathing tubes' instead of 'tracheae')
Not structuring 5-mark answers into clear sub-points (a, b, c) — examiners may miss mark-worthy statements buried in paragraphs

Additional Practice Questions for Self-Assessment

Self-assessment is key to mastering Chapter 6. Below are two bonus questions — one 3-mark and one 5-mark — that students can attempt on their own, then compare with the model answers. Writing answers on paper, timing yourself (roughly 1.5 minutes per mark), and self-checking against the model helps identify gaps. Parents can use these questions during weekend revision sessions. Schools in cities like Delhi, Mumbai, Bengaluru, and Pune often include similar questions in periodic tests and pre-board exams, so practicing a variety strengthens exam confidence.

How CBSETUTOR.ai Helps Students Master Respiration in Organisms

Many Class 7 students find it hard to visualize cellular processes or remember the differences between aerobic and anaerobic respiration. Coaching centres in metros charge ₹5,000-8,000 per month, and private tutors may not always be available for quick doubt clearing. CBSETUTOR.ai offers a smarter, more affordable solution: a 24×7 AI tutor accessible on any smartphone. Students can snap a photo of any question from Chapter 6 — whether it is a tricky MCQ, a diagram to label, or a 5-mark case study — and receive a step-by-step solution in seconds. The AI tutor uses the exact NCERT terminology, so answers align perfectly with CBSE marking schemes. At a flat ₹999 per month for all subjects across Classes 6-12, it costs less than two days of a typical coaching class. Parents in Tier-2 cities, where quality Science coaching is scarce, find this especially valuable. The platform also generates unlimited practice questions, tracks weak areas, and offers video explanations for complex topics like the role of diaphragm and gas exchange in alveoli. A 3-day free trial lets families test the features risk-free, making it easy to see if the child benefits before committing.

24×7 photo-upload doubt solving — snap any question from Respiration in Organisms, get NCERT-aligned solutions instantly
Unlimited practice questions across 1-mark, 2-mark, 3-mark, and 5-mark formats, auto-generated and fresh every time
Video explanations for breathing mechanism, aerobic vs anaerobic respiration, and respiration in different organisms
Affordable at ₹999/month for Classes 6-12, all subjects — one-tenth the cost of metro coaching centres
3-day free trial with no credit card required — parents and students can explore features and decide
Particularly helpful for students in towns without specialized Science coaching, ensuring equal access to quality guidance

Tips for Scoring Full Marks in Chapter 6 Exams

Scoring well in Respiration in Organisms requires a blend of memorization, understanding, and exam technique. First, learn the definitions of breathing, respiration, aerobic respiration, and anaerobic respiration word-for-word from the NCERT textbook; these appear in at least two questions every exam. Second, practice drawing and labelling diagrams — human respiratory system, diaphragm during inhalation and exhalation, and stomata — until you can do them neatly in under three minutes. Third, make a comparison table for aerobic versus anaerobic respiration (oxygen requirement, products, energy yield) and revise it weekly. Fourth, read the 'Do You Know' and 'Activity' sections in NCERT; CBSE sometimes lifts questions directly from these. Fifth, when answering 5-mark questions, always structure your response into clear points or sub-parts (a, b, c) so the examiner can easily spot each mark-worthy statement. Sixth, use scientific terms consistently — 'stomata' not 'leaf pores,' 'tracheae' not 'air tubes,' 'lactic acid' not 'acid.' Seventh, manage time: spend no more than 5-6 minutes on a 5-mark question, 2-3 minutes on a 3-mark question, and under a minute on 1-mark MCQs. Finally, attempt mock tests under timed conditions and self-correct using the NCERT solutions and question banks like this one. Regular practice transforms conceptual understanding into exam-ready performance.

Memorize key definitions verbatim from NCERT — breathing, respiration, aerobic, anaerobic, cellular respiration
Master three diagrams: human respiratory system, diaphragm positions, stomata structure — practice until you can draw them in under 3 minutes
Create and revise a comparison table for aerobic vs anaerobic respiration (oxygen, products, energy)
Read NCERT 'Do You Know' and 'Activities' — CBSE often sources questions from these boxes
Structure 5-mark answers into sub-points (a, b, c) for clarity and easy examiner marking
Use exact scientific terms consistently — marks are lost for informal or incorrect terminology
Time yourself: 1 min per 1-mark, 2-3 min per 3-mark, 5-6 min per 5-mark question
Attempt at least two full-length mock tests before exams and self-correct using answer keys

Frequently asked questions

How many marks does Chapter 6 Respiration in Organisms carry in CBSE Class 7 Science exams?+

Chapter 6 typically carries 4-6 marks in terminal exams and 5-8 marks in periodic tests. Questions range from 1-mark MCQs to 5-mark case-based problems. Schools often include one diagram-based question worth 2-3 marks.

What is the difference between breathing and respiration?+

Breathing is the physical process of inhaling oxygen and exhaling carbon dioxide through the nose and lungs. Respiration is the biochemical process occurring inside cells where glucose is broken down to release energy. This distinction is a favorite 2-mark question.

Which topics from Chapter 6 are most important for exams?+

Cellular respiration (definition and process), aerobic versus anaerobic respiration (differences, products, examples), human breathing mechanism (role of diaphragm), and respiration in plants (stomata, lenticels) and animals (gills, tracheae) are the highest-weightage areas. Diagram questions on the respiratory system and stomata are also common.

What are the end products of aerobic and anaerobic respiration?+

Aerobic respiration produces carbon dioxide, water, and a large amount of energy (38 ATP). Anaerobic respiration in animals produces lactic acid and less energy (2 ATP); in yeast and plants, it produces ethanol, carbon dioxide, and less energy. This is frequently tested in 2-mark and 3-mark questions.

How should I prepare diagrams for Chapter 6?+

Practice drawing the human respiratory system (trachea, bronchi, lungs, diaphragm, alveoli), diaphragm position during inhalation and exhalation, and stomata structure. Use a pencil, label neatly with arrows, and memorize spellings of parts. Allocate 3-4 minutes per diagram in the exam.

Why do we get muscle cramps during heavy exercise?+

During heavy exercise, muscle cells need more energy. When oxygen supply is insufficient, muscles perform anaerobic respiration, producing lactic acid. Accumulation of lactic acid causes pain and cramps. This is a popular 2-mark or 3-mark exam question.

How do fish breathe underwater?+

Fish have gills. Water enters through the mouth, passes over the gills where oxygen dissolved in water diffuses into the blood, and carbon dioxide diffuses out. Water exits through gill slits. This is often a 2-mark or 3-mark question.

What is the role of stomata in respiration?+

Stomata are tiny pores on leaf surfaces, mainly on the lower side, surrounded by guard cells. They allow exchange of gases: oxygen enters for respiration and carbon dioxide exits. During the day, stomata also facilitate gas exchange for photosynthesis. This appears in 2-mark and 3-mark questions.

How does CBSETUTOR.ai help with Chapter 6 doubts?+

CBSETUTOR.ai provides 24×7 AI-powered doubt solving. Students can upload a photo of any question from Respiration in Organisms and receive step-by-step solutions using exact NCERT terminology. It costs ₹999/month for all subjects (Classes 6-12) and offers a 3-day free trial, making quality Science help affordable and accessible anytime.

What are common mistakes students make in Chapter 6 exams?+

Common mistakes include confusing breathing with respiration, writing 'alcohol' for anaerobic respiration in muscles (correct answer: lactic acid), incomplete product lists for aerobic respiration, missing diagram labels, using informal terms instead of scientific ones, and not structuring 5-mark answers into clear sub-points.

How much time should I spend on a 5-mark question from this chapter?+

Allocate 5-6 minutes for a 5-mark question. Write the answer in clear sub-points (a, b, c), use NCERT terminology, and include examples or product names. Practicing timed answers improves speed and ensures you complete the entire paper.

Are there case-based questions from Respiration in Organisms in CBSE exams?+

Yes, CBSE increasingly includes 5-mark case-based questions presenting real-life scenarios like exercise-induced muscle pain, bread dough rising, or fish in oxygen-depleted water. Students must identify the type of respiration, explain the process, and name products to score full marks.

Related resources

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