50 Most Important NEET PYQs of Chapter 17: Breathing and Exchange of Gases – Part 1 (Q1–25)
🔥 50 Most Important NEET PYQs of Chapter 17: Breathing and Exchange of Gases – Part 1 (Q1–25)
📚 By neetpyqall | biologyatease1.blogspot.com
Here’s Part 1 of Chapter 17: Breathing and Exchange of Gases, with the first 25 important NEET questions!
1. Which structure prevents the collapse of trachea?
A) Smooth muscle
B) Cartilaginous rings
C) Pleural fluid
D) Diaphragm
✅ Answer: B) Cartilaginous rings
🧠 Explanation: C-shaped cartilaginous rings keep the trachea open during breathing.
2. The functional unit of lungs is:
A) Bronchiole
B) Alveolus
C) Trachea
D) Bronchus
✅ Answer: B) Alveolus
🧠 Explanation: Gas exchange occurs in the alveoli.
3. Respiratory pigment in humans is:
A) Haemocyanin
B) Hemoglobin
C) Chlorocruorin
D) Haemerythrin
✅ Answer: B) Hemoglobin
🧠 Explanation: Hemoglobin transports oxygen in blood.
4. The volume of air remaining in lungs after normal expiration is called:
A) Residual volume
B) Tidal volume
C) Vital capacity
D) Total lung capacity
✅ Answer: A) Residual volume
🧠 Explanation: Residual volume prevents lung collapse.
5. Normal tidal volume in human adults is about:
A) 1000 mL
B) 500 mL
C) 1500 mL
D) 300 mL
✅ Answer: B) 500 mL
🧠 Explanation: Tidal volume refers to normal inhaled/exhaled air per breath.
6. In which form is most carbon dioxide carried in blood?
A) Dissolved in plasma
B) As carbamino-haemoglobin
C) As bicarbonate
D) Bound to WBCs
✅ Answer: C) As bicarbonate
🧠 Explanation: About 70% of CO₂ is transported as bicarbonate ions.
7. The enzyme that facilitates conversion of CO₂ and water to carbonic acid is:
A) Carboxylase
B) Catalase
C) Carbonic anhydrase
D) Sucrase
✅ Answer: C) Carbonic anhydrase
🧠 Explanation: Found in RBCs, it speeds up the reaction.
8. Breathing rate is regulated primarily by:
A) Oxygen levels
B) Carbon dioxide levels
C) Nitrogen levels
D) ATP levels
✅ Answer: B) Carbon dioxide levels
🧠 Explanation: CO₂ concentration affects respiratory centers in the brain.
9. Which part of brain controls respiration?
A) Cerebrum
B) Cerebellum
C) Medulla oblongata
D) Hypothalamus
✅ Answer: C) Medulla oblongata
🧠 Explanation: The medulla’s respiratory centers regulate breathing rhythm.
10. Total Lung Capacity (TLC) is:
A) VC + RV
B) TV + IRV + ERV
C) VC - RV
D) IRV + ERV
✅ Answer: A) VC + RV
🧠 Explanation: TLC is vital capacity plus residual volume.
11. The exchange of gases in alveoli occurs by:
A) Active transport
B) Diffusion
C) Osmosis
D) Endocytosis
✅ Answer: B) Diffusion
🧠 Explanation: Gases move from high to low concentration.
12. Bohr effect is related to:
A) Oxygen carrying capacity
B) CO₂ transport
C) Effect of CO₂ on hemoglobin's O₂ binding
D) Blood clotting
✅ Answer: C) Effect of CO₂ on hemoglobin's O₂ binding
🧠 Explanation: Increased CO₂ lowers blood pH and reduces hemoglobin’s oxygen affinity.
13. Which gas has the highest diffusion rate?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Hydrogen
✅ Answer: D) Hydrogen
🧠 Explanation: Lighter gases like hydrogen diffuse fastest.
14. In humans, inspiration is initiated by:
A) Contraction of diaphragm
B) Relaxation of diaphragm
C) Contraction of lungs
D) Relaxation of ribs
✅ Answer: A) Contraction of diaphragm
🧠 Explanation: The diaphragm contracts and flattens to allow air into lungs.
15. The primary site of exchange of gases is:
A) Bronchi
B) Bronchioles
C) Alveoli
D) Trachea
✅ Answer: C) Alveoli
🧠 Explanation: Thin walls and rich blood supply make alveoli ideal for gas exchange.
16. Oxygen dissociation curve shifts to the right due to:
A) Low CO₂
B) High CO₂
C) Low temperature
D) High oxygen
✅ Answer: B) High CO₂
🧠 Explanation: High CO₂ or low pH causes a rightward shift (Bohr effect).
17. Which of the following has maximum affinity for oxygen?
A) Myoglobin
B) Hemoglobin
C) Haemocyanin
D) Chlorocruorin
✅ Answer: A) Myoglobin
🧠 Explanation: Myoglobin holds oxygen tightly, especially in muscles.
18. The percentage of oxygen transported by hemoglobin is:
A) 50%
B) 70%
C) 97%
D) 10%
✅ Answer: C) 97%
🧠 Explanation: Most oxygen is carried by hemoglobin, a small amount is dissolved in plasma.
19. Respiratory volume that remains in lungs after forced expiration is:
A) Tidal volume
B) Inspiratory reserve volume
C) Residual volume
D) Expiratory reserve volume
✅ Answer: C) Residual volume
🧠 Explanation: This ensures that alveoli do not collapse.
20. Haemoglobin is made up of:
A) 2 polypeptides
B) 3 polypeptides
C) 4 polypeptides
D) 5 polypeptides
✅ Answer: C) 4 polypeptides
🧠 Explanation: Hemoglobin has two alpha and two beta chains.
21. Which one is the correct sequence of respiratory passage in man?
A) Pharynx → Larynx → Trachea → Bronchi → Alveoli
B) Larynx → Pharynx → Trachea → Bronchi → Alveoli
C) Trachea → Bronchi → Pharynx → Alveoli
D) Pharynx → Trachea → Larynx → Bronchi → Alveoli
✅ Answer: A) Pharynx → Larynx → Trachea → Bronchi → Alveoli
🧠 Explanation: Correct anatomical sequence of air passage.
22. Which of the following will increase the breathing rate?
A) Increase in O₂ concentration
B) Decrease in CO₂ concentration
C) Increase in CO₂ concentration
D) Decrease in pH
✅ Answer: C) Increase in CO₂ concentration
🧠 Explanation: High CO₂ levels stimulate respiratory centers to increase breathing.
23. Which of the following is NOT a respiratory organ in any animal?
A) Skin
B) Gills
C) Lungs
D) Heart
✅ Answer: D) Heart
🧠 Explanation: The heart pumps blood but does not exchange gases.
24. Which of the following is NOT involved in breathing movements?
A) Intercostal muscles
B) Diaphragm
C) Abdominal muscles
D) Cardiac muscles
✅ Answer: D) Cardiac muscles
🧠 Explanation: Cardiac muscles belong to the heart, not involved in breathing.
25. In mammals, oxygen binds with hemoglobin in:
A) Lungs
B) Tissue
C) Heart
D) Blood plasma
✅ Answer: A) Lungs
🧠 Explanation: Oxygen binding occurs in the lungs where oxygen concentration is high.
✅ Part 1 complete!
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