NEET MCQs Practice | Chapter-BREATHING AND EXCHANGE OF GASES | Biology Class 11
Here You Get So Many MCQs Questions Based On NEET Of Class 11 Biology, Chapter ,BREATHING AND EXCHANGE OF GASESIf You Want To Read Our Quality Notes Of Chapter, BREATHING AND EXCHANGE OF GASES Click Here 🥰MCQ 1: Oxygen is essential for living organisms because it helps in:
A) Storing energy in glucose
B) Breaking down food molecules to release energy
C) Producing carbon dioxide only
D) Transporting water in plants
Answer: B) Breaking down food molecules to release energy
MCQ 2: Which gas is produced as a waste during energy release in the body?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Hydrogen
Answer: C) Carbon dioxide
MCQ 3: The process of taking in oxygen and removing carbon dioxide from the body is called:
A) Respiration
B) Photosynthesis
C) Breathing
D) Circulation
Answer: C) Breathing
MCQ 4: The upward and downward movement of the chest during breathing indicates:
A) Heart pumping blood
B) Gas exchange
C) Air going in and out of the lungs
D) Digestion of food
Answer: C) Air going in and out of the lungs
MCQ 5: Which of the following is NOT a function of respiratory organs?
A) Taking in oxygen
B) Removing carbon dioxide
C) Producing energy directly
D) Helping in breathing
Answer: C) Producing energy directly
MCQ 6: Which of the following animals exchange gases by simple diffusion through their body surface?
A) Earthworms
B) Sponges and flatworms
C) Insects
D) Mammals
Answer: B) Sponges and flatworms
MCQ 7: Earthworms respire through:
A) Lungs
B) Tracheal system
C) Moist skin (cuticle)
D) Gills
Answer: C) Moist skin (cuticle)
MCQ 8: The respiratory system of insects is called:
A) Lungs
B) Gills
C) Tracheal system
D) Cutaneous system
Answer: C) Tracheal system
MCQ 9: Branchial respiration is seen in:
A) Insects
B) Aquatic arthropods and molluscs
C) Mammals
D) Amphibians
Answer: B) Aquatic arthropods and molluscs
MCQ 10: Pulmonary respiration occurs in:
A) Fish only
B) Amphibians only
C) Reptiles, birds, and mammals
D) Earthworms
Answer: C) Reptiles, birds, and mammals
MCQ 11: Amphibians like frogs can respire through:
A) Only lungs
B) Only skin
C) Lungs and moist skin
D) Tracheal system
Answer: C) Lungs and moist skin
MCQ 12: Where are the external nostrils located?
A) Below the lower lips
B) Above the upper lips
C) On the cheeks
D) At the back of the throat
Answer: B) Above the upper lips
MCQ 13: The nasal chamber opens into which part of the respiratory system?
A) Larynx
B) Pharynx
C) Trachea
D) Bronchioles
Answer: B) Pharynx
MCQ 14: Which part of the respiratory system is also known as the sound box?
A) Trachea
B) Larynx
C) Bronchi
D) Epiglottis
Answer: B) Larynx
MCQ 15: What prevents food from entering the larynx during swallowing?
A) Trachea
B) Epiglottis
C) Bronchi
D) Pharynx
Answer: B) Epiglottis
MCQ 16: The trachea divides into primary bronchi at the level of:
A) 3rd thoracic vertebra
B) 5th thoracic vertebra
C) 7th cervical vertebra
D) 1st lumbar vertebra
Answer: B) 5th thoracic vertebra
MCQ 17: What supports the trachea, bronchi, and initial bronchioles and keeps the airways open?
A) Muscles
B) Complete rings of cartilage
C) Incomplete rings of cartilage
D) Pleural membranes
Answer: C) Incomplete rings of cartilage
MCQ 18: Where does gas exchange of oxygen and carbon dioxide occur?
A) Bronchi
B) Bronchioles
C) Alveoli
D) Trachea
Answer: C) Alveoli
MCQ 19: What is the fluid present between the layers of the pleura called, and what is its function?
A) Blood; transports gases
B) Lymph; protects lungs
C) Pleural fluid; reduces friction during lung movement
D) Interstitial fluid; strengthens lungs
Answer: C) Pleural fluid; reduces friction during lung movement
MCQ 20: The part of the respiratory system from nostrils to terminal bronchioles is called:
A) Respiratory part
B) Exchange part
C) Conducting part
D) Alveolar part
Answer: C) Conducting part
MCQ 21: Which structure forms the thoracic cavity?
A) Skull, ribs, sternum, diaphragm
B) Vertebral column, sternum, ribs, diaphragm
C) Vertebral column, clavicle, ribs, lungs
D) Sternum, ribs, diaphragm, lungs
Answer: B) Vertebral column, sternum, ribs, diaphragm
MCQ 22: Which process refers to the movement of air in and out of the lungs?
A) Gas diffusion
B) Pulmonary ventilation (breathing)
C) Cellular respiration
D) Gas transport
Answer: B) Pulmonary ventilation (breathing)
MCQ 23: During gas diffusion across the alveolar membrane, what happens?
A) Oxygen leaves the blood and CO₂ enters the alveoli
B) Oxygen enters the blood and CO₂ leaves the blood
C) Oxygen enters tissues directly from alveoli
D) Carbon dioxide enters the tissues
Answer: B) Oxygen enters the blood and CO₂ leaves the blood
MCQ 24: What is the main function of blood in respiratory gas transport?
A) Carry nutrients only
B) Carry oxygen and carbon dioxide to and from tissues
C) Produce oxygen in the lungs
D) Absorb CO₂ into alveoli only
Answer: B) Carry oxygen and carbon dioxide to and from tissues
MCQ 25: How do gases move between blood and body tissues?
A) By active transport
B) Oxygen goes into tissues and CO₂ comes back into blood by diffusion
C) By filtration through membranes
D) Blood pumps gases mechanically
Answer: B) Oxygen goes into tissues and CO₂ comes back into blood by diffusion
MCQ 26: What happens during cellular respiration?
A) Oxygen is released into the alveoli
B) Cells use oxygen to break down nutrients and release carbon dioxide
C) Blood carries gases only
D) Carbon dioxide is absorbed into the lungs
Answer: B) Cells use oxygen to break down nutrients and release carbon dioxide
MCQ 27: What is the tidal volume (TV) in a healthy person?
A) 1000 mL
B) 500 mL
C) 2500 mL
D) 1100 mL
Answer: B) 500 mL
MCQ 28: Which lung volume represents the extra air a person can breathe out after a normal exhalation?
A) Inspiratory Reserve Volume (IRV)
B) Tidal Volume (TV)
C) Expiratory Reserve Volume (ERV)
D) Residual Volume (RV)
Answer: C) Expiratory Reserve Volume (ERV)
MCQ 29: What does the inspiratory capacity (IC) include?
A) TV + ERV
B) TV + IRV
C) ERV + RV
D) TV + RV
Answer: B) TV + IRV
MCQ 30: Functional Residual Capacity (FRC) is calculated as:
A) ERV + RV
B) TV + IRV
C) ERV + TV
D) TV + IRV + ERV
Answer: A) ERV + RV
MCQ 31: Which lung capacity represents the maximum amount of air the lungs can hold?
A) Vital Capacity (VC)
B) Total Lung Capacity (TLC)
C) Tidal Volume (TV)
D) Inspiratory Capacity (IC)
Answer: B) Total Lung Capacity (TLC)
MCQ 32: Where does the primary gas exchange occur in the human lungs?
A) Bronchioles
B) Alveoli
C) Trachea
D) Pharynx
Answer: B) Alveoli
MCQ 33: Gas exchange in humans occurs mainly by:
A) Active transport
B) Facilitated diffusion
C) Simple diffusion
D) Endocytosis
Answer: C) Simple diffusion
MCQ 34: What determines the direction of gas movement during exchange?
A) Blood flow rate
B) Partial pressure gradient
C) Heart rate
D) Lung volume
Answer: B) Partial pressure gradient
MCQ 35: What is the partial pressure of oxygen (pO₂) in alveolar air?
A) 40 mm Hg
B) 45 mm Hg
C) 95 mm Hg
D) 104 mm Hg
Answer: D) 104 mm Hg
MCQ 36: In which direction does carbon dioxide move during gas exchange?
A) Alveoli → blood → tissues
B) Tissues → blood → alveoli
C) Blood → alveoli → tissues
D) Tissues → alveoli → blood
Answer: B) Tissues → blood → alveoli
MCQ 37: What is the partial pressure of oxygen (pO₂) in atmospheric air?
A) 104 mm Hg
B) 95 mm Hg
C) 159 mm Hg
D) 40 mm Hg
Answer: C) 159 mm Hg
MCQ 38: What is the partial pressure of carbon dioxide (pCO₂) in atmospheric air?
A) 0.3 mm Hg
B) 40 mm Hg
C) 45 mm Hg
D) 104 mm Hg
Answer: A) 0.3 mm Hg
MCQ 39: What is the partial pressure of oxygen in alveolar air?
A) 40 mm Hg
B) 104 mm Hg
C) 95 mm Hg
D) 159 mm Hg
Answer: B) 104 mm Hg
MCQ 40: Deoxygenated blood arriving at the lungs has about:
A) 95 mm Hg O₂ and 40 mm Hg CO₂
B) 40 mm Hg O₂ and 45 mm Hg CO₂
C) 104 mm Hg O₂ and 40 mm Hg CO₂
D) 159 mm Hg O₂ and 0.3 mm Hg CO₂
Answer: B) 40 mm Hg O₂ and 45 mm Hg CO₂
MCQ 41: Oxygenated blood leaving the lungs has about:
A) 104 mm Hg O₂ and 40 mm Hg CO₂
B) 95 mm Hg O₂ and 40 mm Hg CO₂
C) 40 mm Hg O₂ and 45 mm Hg CO₂
D) 159 mm Hg O₂ and 0.3 mm Hg CO₂
Answer: B) 95 mm Hg O₂ and 40 mm Hg CO₂
MCQ 42: Why is carbon dioxide removed more efficiently than oxygen despite a smaller partial pressure gradient?
A) It has higher solubility in plasma
B) It has lower solubility in plasma
C) Its molecular weight is lower
D) Oxygen is actively transported
Answer: A) It has higher solubility in plasma
MCQ 43: By how many times is CO₂ more soluble than O₂ in plasma?
A) 2–3 times
B) 10–12 times
C) 20–25 times
D) 50 times
Answer: C) 20–25 times
MCQ 44: The rate of gas exchange depends on:
A) Partial pressure only
B) Gas solubility only
C) Thickness of the diffusion membrane only
D) Partial pressure gradient, solubility, and membrane thickness
Answer: D) Partial pressure gradient, solubility, and membrane thickness
MCQ 45: The diffusion membrane in human lungs is composed of:
A) Only squamous epithelium of alveoli
B) Only endothelium of alveolar capillaries
C) Epithelium, endothelium, and basement membrane
D) Only basement membrane
Answer: C) Epithelium, endothelium, and basement membrane
MCQ 46: What is the approximate thickness of the alveolar diffusion membrane?
A) 1 cm
B) 1 mm
C) Less than 1 mm
D) 10 mm
Answer: C) Less than 1 mm
MCQ 47: Which factor ensures efficient oxygen delivery to tissues?
A) Thick alveolar membrane
B) Steep partial pressure gradient
C) Low solubility of CO₂
D) Slow blood flow
Answer: B) Steep partial pressure gradient
MCQ 48: Which structural adaptation supports rapid gas exchange in humans?
A) Thick bronchi walls
B) Thin diffusion membrane and alveoli
C) Low blood supply to lungs
D) Large trachea diameter
Answer: B) Thin diffusion membrane and alveoli
MCQ 49: What percentage of oxygen is transported by red blood cells in the blood?
A) 70%
B) 97%
C) 25%
D) 3%
Answer: B) 97%
MCQ 50: How is the remaining 3% of oxygen transported in the blood?
A) Bound to hemoglobin
B) As bicarbonate ions
C) Dissolved in plasma
D) As carbonic acid
Answer: C) Dissolved in plasma
MCQ 51: Approximately what percentage of carbon dioxide is transported as bicarbonate ions in plasma?
A) 7%
B) 20–25%
C) 70%
D) 97%
Answer: C) 70%
MCQ 52: What percentage of CO₂ is carried by red blood cells?
A) 70%
B) 20–25%
C) 7%
D) 97%
Answer: B) 20–25%
MCQ 53: Which pigment in RBCs binds oxygen for transport?
A) Myoglobin
B) Hemoglobin
C) Chlorophyll
D) Carotene
Answer: B) Hemoglobin
MCQ 54: How many oxygen molecules can a single hemoglobin molecule carry at maximum?
A) 1
B) 2
C) 3
D) 4
Answer: D) 4
MCQ 55: What is formed when oxygen binds reversibly with hemoglobin?
A) Carboxyhemoglobin
B) Oxyhemoglobin
C) Carbaminohemoglobin
D) Deoxyhemoglobin
Answer: B) Oxyhemoglobin
MCQ 56: The binding of oxygen to hemoglobin depends mainly on:
A) Partial pressure of carbon dioxide
B) Partial pressure of oxygen
C) pH only
D) Temperature only
Answer: B) Partial pressure of oxygen
MCQ 57: Which factors affect oxygen binding with hemoglobin besides pO₂?
A) Only temperature
B) pCO₂, H⁺ concentration, and temperature
C) Only pH
D) Only plasma volume
Answer: B) pCO₂, H⁺ concentration, and temperature
MCQ 58: What shape is the oxygen dissociation curve?
A) Linear
B) Exponential
C) Sigmoid
D) Hyperbolic
Answer: C) Sigmoid
MCQ 59: Under alveolar conditions (lungs), oxygen binds to hemoglobin because:
A) pO₂ is low, pCO₂ is high
B) pO₂ is high, pCO₂ is low, H⁺ concentration is low, and temperature is lower
C) pO₂ is low, temperature is high
D) H⁺ concentration is high, pCO₂ is high
Answer: B) pO₂ is high, pCO₂ is low, H⁺ concentration is low, and temperature is lower
MCQ 60: In body tissues, oxygen is released from hemoglobin because:
A) pO₂ is high, pCO₂ is low
B) pO₂ is low, pCO₂ is high, H⁺ concentration is high, and temperature is higher
C) H⁺ concentration is low, pCO₂ is low
D) Temperature is lower
Answer: B) pO₂ is low, pCO₂ is high, H⁺ concentration is high, and temperature is higher
MCQ 61: How much oxygen is delivered to tissues by 100 ml of oxygenated blood under normal conditions?
A) 2 ml
B) 5 ml
C) 10 ml
D) 20 ml
Answer: B) 5 ml
MCQ 62: Approximately what percentage of CO₂ in the body is carried by hemoglobin as carbamino-hemoglobin?
A) 5–10%
B) 20–25%
C) 50–55%
D) 70%
Answer: B) 20–25%
MCQ 63: The binding of CO₂ to hemoglobin depends on:
A) pO₂ only
B) pCO₂ only
C) Both pCO₂ and pO₂
D) Temperature only
Answer: C) Both pCO₂ and pO₂
MCQ 64: In tissues, more CO₂ binds to hemoglobin because:
A) pCO₂ is low and pO₂ is high
B) pCO₂ is high and pO₂ is low
C) pO₂ is high and temperature is low
D) pCO₂ is low and H⁺ concentration is low
Answer: B) pCO₂ is high and pO₂ is low
MCQ 65: In alveoli, CO₂ is released from hemoglobin because:
A) pCO₂ is high and pO₂ is low
B) pCO₂ is low and pO₂ is high
C) Temperature is high
D) Carbonic anhydrase is inactive
Answer: B) pCO₂ is low and pO₂ is high
MCQ 66: Which enzyme in RBCs helps convert CO₂ to bicarbonate (HCO₃⁻) and back?
A) Hemoglobin
B) Carbonic anhydrase
C) Cytochrome oxidase
D) Catalase
Answer: B) Carbonic anhydrase
MCQ 67: What is the sequence of reactions catalyzed by carbonic anhydrase in tissues?
A) CO₂ → O₂ → H₂O
B) CO₂ + H₂O → H₂CO₃ → HCO₃⁻ + H⁺
C) CO₂ → H₂O → O₂
D) H₂O + O₂ → H₂CO₃ → CO₂
Answer: B) CO₂ + H₂O → H₂CO₃ → HCO₃⁻ + H⁺
MCQ 68: During exhalation at alveoli, the reaction reverses to release CO₂. This means:
A) HCO₃⁻ + H⁺ → H₂CO₃ → CO₂ + H₂O
B) CO₂ → H₂CO₃ → HCO₃⁻ + H⁺
C) O₂ + H₂O → CO₂
D) H⁺ + O₂ → CO₂
Answer: A) HCO₃⁻ + H⁺ → H₂CO₃ → CO₂ + H₂O
MCQ 69: How much CO₂ is released from every 100 ml of deoxygenated blood at the alveoli?
A) 1 ml
B) 2 ml
C) 4 ml
D) 8 ml
Answer: C) 4 ml
MCQ 70: Which part of the brain primarily controls the human breathing rate?
A) Cerebellum
B) Medulla oblongata
C) Hypothalamus
D) Thalamus
Answer: B) Medulla oblongata
MCQ 71: The respiratory rhythm centre is influenced by another brain centre called:
A) Cardiac centre
B) Pneumotaxic centre
C) Olfactory centre
D) Visual cortex
Answer: B) Pneumotaxic centre
MCQ 72: The pneumotaxic centre primarily regulates:
A) Depth of exhalation
B) Length of inspiration and breathing rate
C) Oxygen saturation
D) Heart rate
Answer: B) Length of inspiration and breathing rate
MCQ 73: The chemosensitive area near the rhythm centre responds to:
A) Oxygen only
B) Carbon dioxide (CO₂) and hydrogen ions (H⁺)
C) Nitrogen
D) Glucose concentration
Answer: B) Carbon dioxide (CO₂) and hydrogen ions (H⁺)
MCQ 74: When CO₂ and H⁺ levels rise, the chemosensitive area signals the rhythm centre to:
A) Decrease breathing rate
B) Increase breathing rate and remove excess CO₂ and H⁺
C) Stop breathing temporarily
D) Increase oxygen storage only
Answer: B) Increase breathing rate and remove excess CO₂ and H⁺
MCQ 75: Which peripheral structures detect changes in CO₂ and H⁺ levels in blood and signal the respiratory centre?
A) Kidneys and liver
B) Aortic arch and carotid artery
C) Lungs and bronchi
D) Pancreas and spleen
Answer: B) Aortic arch and carotid artery
MCQ 76: Which gas plays a minor role in controlling the breathing rate?
A) Carbon dioxide
B) Oxygen
C) Nitrogen
D) Hydrogen
Answer: B) Oxygen
MCQ 77: Emphysema primarily affects which part of the respiratory system?
A) Bronchi
B) Alveoli
C) Trachea
D) Larynx
Answer: B) Alveoli
MCQ 78: What is a major cause of emphysema?
A) Viral infection
B) Cigarette smoking
C) Bacterial infection
D) Air pollution only
Answer: B) Cigarette smoking
MCQ 79: Asthma is mainly caused by:
A) Damage to alveoli
B) Inflammation of bronchi and bronchioles
C) Collapse of trachea
D) Thickening of pleura
Answer: B) Inflammation of bronchi and bronchioles
MCQ 80: The wheezing sound in asthma is due to:
A) Collapsed alveoli
B) Obstruction in airways
C) Stiffening of diaphragm
D) Broken ribs
Answer: B) Obstruction in airways
MCQ 81: Occupational respiratory disorders often occur due to:
A) Viral infections at workplace
B) Excessive inhalation of dust
C) Lack of oxygen in workplace
D) Smoking only
Answer: B) Excessive inhalation of dust
MCQ 82: Occupational respiratory disorders can lead to:
A) Asthma only
B) Emphysema only
C) Fibrosis and lung damage
D) Pneumothorax
Answer: C) Fibrosis and lung damage
MCQ 83: A preventive measure for occupational respiratory disorders is:
A) Vaccination
B) Protective masks
C) Taking antibiotics daily
D) Avoiding water intake
Answer: B) Protective masks
MCQ 84: What is the primary reason cells need oxygen?
A) To remove carbon dioxide
B) To carry out metabolism and produce energy
C) To increase blood flow
D) To help in nerve conduction
Answer: B) To carry out metabolism and produce energy
MCQ 85: Which of the following is the first step of respiration?
A) Gas exchange in tissues
B) Cellular respiration
C) Breathing (inspiration and expiration)
D) Transport of gases by blood
Answer: C) Breathing (inspiration and expiration)
MCQ 86: The process by which oxygen and carbon dioxide move between alveoli and blood is called:
A) Active transport
B) Diffusion
C) Osmosis
D) Filtration
Answer: B) Diffusion
MCQ 87: Oxygen moves from alveoli to blood because:
A) Oxygen is heavier than CO₂
B) Of partial pressure gradient (high in alveoli, low in blood)
C) Active pumping by lungs
D) Oxygen is soluble in water
Answer: B) Of partial pressure gradient (high in alveoli, low in blood)
MCQ 88: Most oxygen in blood is transported by:
A) Plasma in dissolved form
B) White blood cells
C) Hemoglobin in red blood cells
D) Platelets
Answer: C) Hemoglobin in red blood cells
MCQ 89: In tissues where pO₂ is low and pCO₂ is high, what happens to oxygen?
A) It binds more strongly to hemoglobin
B) It is released from hemoglobin to tissues
C) It converts into CO₂
D) It remains unchanged
Answer: B) It is released from hemoglobin to tissues
MCQ 90: Which form carries the majority of CO₂ in the blood?
A) Dissolved CO₂ in plasma
B) Carbamino-hemoglobin
C) Bicarbonate ions (HCO₃⁻)
D) Carbonic acid
Answer: C) Bicarbonate ions (HCO₃⁻)
MCQ 91: Which enzyme helps in converting CO₂ to bicarbonate ions for transport?
A) Amylase
B) Carbonic anhydrase
C) Lipase
D) Catalase
Answer: B) Carbonic anhydrase
MCQ 92: Which part of the brain primarily controls the rhythm of breathing?
A) Cerebellum
B) Medulla (respiratory centre)
C) Hypothalamus
D) Pons (pneumotaxic centre)
Answer: B) Medulla (respiratory centre)
MCQ 93: The pneumotaxic centre in the pons is responsible for:
A) Controlling oxygen transport
B) Adjusting the rate and depth of breathing
C) Producing red blood cells
D) Sensing tissue pO₂
Answer: B) Adjusting the rate and depth of breathing
MCQ 94: Chemosensitive areas in the medulla respond mainly to:
A) Oxygen levels in blood
B) Carbon dioxide (CO₂) and hydrogen ion (H⁺) levels
C) Glucose levels
D) Nitrogen concentration
Answer: B) Carbon dioxide (CO₂) and hydrogen ion (H⁺) levels
