Last Updated on September 27, 2025 by XAM CONTENT
To succeed in Class 11 Biology exams, a strong grasp of Chapter 14 – Breathing and Exchange of Gases is essential. Our comprehensive collection of chapterwise MCQ questions with answers for Class 11 Biology is designed according to the latest syllabus and exam guidelines, ensuring targeted preparation and better performance. It is a part of MCQ Questions for CBSE Class 11 Biology Series.
These multiple-choice questions will help you assess your knowledge, improve accuracy, and boost confidence for your exams. Whether you are preparing for school tests, online tests or competitive exams, these Breathing and Exchange of Gases MCQs will strengthen your conceptual clarity.
| Chapter | Breathing and Exchange of Gases |
| Book | Biology for Class 11 |
| Type of Questions | MCQ Questions |
| Nature of Questions | Competency Based Questions |
| Board | CBSE |
| Class | 11 |
| Subject | Biology |
| Useful for | Class 11 Studying Students |
| Answers provided | Yes |
| Difficulty level | Mentioned |
| Important Link | Class 11 Biology Chapterwise MCQ Questions |
MCQ Questions on Breathing and Exchange of Gases Class 11 Biology (PDF Download)
Question 1.Which structure prevents the entry of food into the larynx during swallowing?
(a) Epiglottis
(b) Glottis
(c) Pharynx
(d) Trachea
Show Answer
Answer: (a) Epiglottis
Explanation: Epiglottis is a thin flap that closes over the glottis during swallowing to prevent food from entering the respiratory tract.
Which of the following is the actual site of gaseous exchange in human lungs?
(a) Bronchi
(b) Alveoli
(c) Trachea
(d) Bronchioles
Show Answer
Answer: (b) Alveoli
Explanation: Alveoli are thin-walled vascular structures where diffusion of O₂ and CO₂ occurs across the respiratory membrane.
Inspiration occurs when:
(a) Intrapulmonary pressure is less than atmospheric pressure
(b) Intrapulmonary pressure is greater than atmospheric pressure
(c) Atmospheric pressure equals intrapulmonary pressure
(d) None of these
Show Answer
Answer: (a) Intrapulmonary pressure is less than atmospheric pressure
Explanation: Negative pressure inside the lungs compared to the atmosphere allows air to move in.
Which of the following volumes represents the maximum amount of air a person can breathe out after a forced inspiration?
(a) Expiratory reserve volume
(b) Residual volume
(c) Vital capacity
(d) Tidal volume
Show Answer
Answer: (c) Vital capacity
Explanation: Vital capacity (VC) = IRV + TV + ERV, maximum volume breathed out after a forced inspiration.
The solubility of CO₂ in blood is how many times greater than O₂?
(a) 2–5 times
(b) 10 times
(c) 20–25 times
(d) Equal
Show Answer
Answer: (c) 20–25 times
Explanation: CO₂ is much more soluble than O₂, hence transported more efficiently as bicarbonates and carbamino compounds.
The partial pressure of oxygen (pO₂) in alveoli is approximately:
(a) 159 mmHg
(b) 95 mmHg
(c) 104 mmHg
(d) 40 mmHg
Show Answer
Answer: (c) 104 mmHg
Explanation: Due to mixing of atmospheric air with residual volume, alveolar pO₂ is 104 mmHg compared to 159 mmHg in atmospheric air.
The Oxygen dissociation curve is:
(a) Linear
(b) Sigmoidal
(c) Hyperbolic
(d) Exponential
Show Answer
Answer: (b) Sigmoidal
Explanation: Due to cooperative binding of O₂ with hemoglobin, the curve is S-shaped (sigmoidal).
Which enzyme catalyzes the conversion of CO₂ and water to carbonic acid in RBCs?
(a) Catalase
(b) Peroxidase
(c) Carbonic anhydrase
(d) Dehydrogenase
Show Answer
Answer: (c) Carbonic anhydrase
Explanation: Carbonic anhydrase present in RBCs rapidly catalyzes the reversible hydration of CO₂.
Most of the oxygen in blood is transported:
(a) Dissolved in plasma
(b) As bicarbonates
(c) Bound to hemoglobin
(d) As carbamino compounds
Show Answer
Answer: (c) Bound to hemoglobin
Explanation: About 97% of oxygen is transported as oxyhemoglobin, only 3% dissolved in plasma.
About how much CO₂ is transported as bicarbonates in blood?
(a) 20-25%
(b) 70%
(c) 7%
(d) 97%
Show Answer
Answer: (b) 70%
Explanation: Majority of CO₂ is transported in plasma as bicarbonates, catalyzed by carbonic anhydrase.
Which respiratory disorder is characterized by destruction of alveolar walls reducing surface area?
(a) Asthma
(b) Emphysema
(c) Bronchitis
(d) Pneumonia
Show Answer
Answer: (b) Emphysema
Explanation: Emphysema is often caused by smoking, leading to reduced respiratory surface and impaired gas exchange.
What is the normal tidal volume (TV) in a healthy adult?
(a) 100 mL
(b) 500 mL
(c) 1000 mL
(d) 2500 mL
Show Answer
Answer: (b) 500 mL
Explanation: Tidal volume is about 500 mL per breath, giving ~6000–8000 mL air exchange per minute.
In tissues, hemoglobin releases oxygen more readily due to:
(a) High pO₂
(b) Low pCO₂
(c) High pCO₂ and H⁺ concentration
(d) Low temperature
Show Answer
Answer: (c) High pCO₂ and H⁺ concentration
Explanation: At tissues, high CO₂, H⁺, and temperature favor O₂ dissociation (Bohr effect).
Respiratory rhythm in humans is primarily regulated by:
(a) Cerebellum
(b) Medulla oblongata
(c) Hypothalamus
(d) Pons
Show Answer
Answer: (b) Medulla oblongata
Explanation: The respiratory rhythm center in medulla regulates breathing rhythm; pneumotaxic center in pons modifies it.
Which disorder is due to inflammation of bronchi and bronchioles leading to wheezing?
(a) Asthma
(b) Bronchitis
(c) Tuberculosis
(d) Silicosis
Show Answer
Answer: (a) Asthma
Explanation: Asthma involves bronchial inflammation and constriction, leading to breathing difficulties and wheezing.
At high altitudes, low oxygen availability leads to:
(a) Hypoxia
(b) Emphysema
(c) Asphyxia
(d) Bronchitis
Show Answer
Answer: (a) Hypoxia
Explanation: Hypoxia is a condition where tissues receive insufficient oxygen, common at high altitudes.
The amount of oxygen released to tissues from 100 mL of oxygenated blood under normal conditions is about:
(a) 1 mL
(b) 2 mL
(c) 5 mL
(d) 10 mL
Show Answer
Answer: (c) 5 mL
Explanation: Each 100 mL of oxygenated blood delivers ~5 mL O₂ to tissues during normal physiology.
What is the average breathing rate of a healthy adult human?
(a) 6–8 breaths/min
(b) 12–16 breaths/min
(c) 20–25 breaths/min
(d) 30–40 breaths/min
Show Answer
Answer: (b) 12–16 breaths/min
Explanation: A normal adult at rest breathes 12–16 times per minute, maintaining efficient gas exchange.
Which part of the brain responds to high CO₂ and H⁺ concentration in blood to adjust respiration?
(a) Chemosensitive area near medulla
(b) Cerebellum
(c) Cerebrum
(d) Hypothalamus
Show Answer
Answer: (a) Chemosensitive area near medulla
Explanation: This area senses CO₂ and H⁺ levels, signaling the respiratory center to adjust breathing rate accordingly.
Which respiratory volume cannot be measured using a spirometer?
(a) Tidal volume
(b) Expiratory reserve volume
(c) Residual volume
(d) Inspiratory reserve volume
Show Answer
Answer: (c) Residual volume
Explanation: Residual volume is the air remaining in lungs after maximum expiration; it cannot be expelled or measured directly with a spirometer.
We hope the given mcq questions with Answers for Breathing and Exchange of Gases Class 11 helps you in your learning.
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Topics from which mcq questions may be asked
- Mechanism of breathing
- Exchange and transport of gases
- Respiratory volumes
Gas exchange fuels life—from lungs to cells, oxygen powers energy.
Frequently Asked Questions (FAQs) on Breathing and Exchange of Gases MCQ Questions
Q1: What is the best way to prepare for Class 11 Biology MCQ questions?
A1: The best way is to study NCERT concepts thoroughly, practice topicwise MCQs regularly. Solving previous year MCQs and mock tests can boost accuracy and speed.
Q2: Are NCERT questions enough for Class 11 Biology MCQ-based exams?
A2: NCERT forms the base for all CBSE Physics MCQs. However, for better preparation, students should solve additional MCQs from reference books and practice HOTS and competency-based questions to develop better understanding.
Q3: Where can I find chapterwise Class 11 Biology MCQ questions with answers?
A3: You can find chapterwise MCQ questions with answers and detailed explanations on trusted educational platforms like xamcontent.com and physicsgurukul.com. These cover both basic and advanced-level questions.
Q4: Do CBSE Class 11 exams include MCQs?
A4: Yes, as per the latest CBSE exam pattern, objective questions, including MCQs, are part of the final exam paper. MCQs test conceptual understanding and application skills.
Q5: How to score high in Class 11 Biology MCQs?
A5: To score high, understand the theory from NCERT, solve a variety of MCQs (basic and conceptual), and regularly revise theory. Avoid guesswork and focus on time management during tests.
