NEET UG Biology Mock Test – Free Online Test with Score

Q1. During normal expiration, which of the following pressure relationships holds true?

A Intrapulmonary pressure < Atmospheric pressure.
B Intrapulmonary pressure = Atmospheric pressure.
C Intrapleural pressure > Atmospheric pressure.
D Intrapulmonary pressure > Atmospheric pressure.

Q2. The pneumotaxic center, located in the pons, has what effect on respiration?

A It prolongs inspiration, increasing respiratory depth.
B It inhibits inspiration, reducing respiratory rate.
C It initiates forceful expiration.
D It stimulates both inspiration and expiration equally.

Q3. Which of the following forms transports the largest percentage of CO2 in the blood?

A As carbaminohemoglobin.
B As bicarbonate ions.
C Dissolved in plasma.
D Bound to plasma proteins.

Q4. During inspiration, the diaphragm:

A Relaxes and moves downward.
B Contracts and moves downward.
C Relaxes and moves upward.
D Contracts and moves upward.

Q5. In patients with pulmonary fibrosis, the thickening of the alveolar membrane significantly reduces gas exchange. This primarily affects which step of respiration?

A Transport
B Ventilation
C Perfusion
D Diffusion

Q6. A spirometry test reveals a patient has a significantly reduced Vital Capacity (VC) but a normal Residual Volume (RV). This pattern is most indicative of:

A An obstructive lung disease, such as emphysema.
B A neurological disorder affecting respiratory muscle strength.
C A primary cardiac condition affecting lung perfusion.
D A restrictive lung disease, such as pulmonary fibrosis.

Q7. The Haldane effect states that the binding of oxygen to hemoglobin facilitates the unloading of CO2 from the blood. This occurs because:

A Oxygen displaces CO2 directly from carbaminohemoglobin.
B Oxygen increases the activity of carbonic anhydrase.
C Oxygenated hemoglobin has a higher affinity for CO2, thus paradoxically reducing CO2 binding.
D Oxygenated hemoglobin has a lower affinity for H+ ions, promoting CO2 release from bicarbonate.

Q8. Which of the following muscle groups is primarily responsible for expanding the thoracic cavity vertically during quiet inspiration?

A Internal intercostals
B External intercostals
C Abdominal recti
D Diaphragm

Q9. Which of the following represents the correct sequence of structures through which air passes during inspiration?

A Pharynx -> Larynx -> Trachea -> Bronchioles -> Bronchi -> Alveoli
B Pharynx -> Larynx -> Trachea -> Bronchi -> Bronchioles -> Alveoli
C Trachea -> Pharynx -> Larynx -> Bronchi -> Bronchioles -> Alveoli
D Larynx -> Pharynx -> Trachea -> Bronchi -> Bronchioles -> Alveoli

Q10. A shift of the oxyhemoglobin dissociation curve to the right would be caused by: 1. Increased PCO2 2. Increased pH 3. Increased temperature 4. Increased 2,3-BPG

A 1, 3 and 4 only
B 1, 2 and 3 only
C 2, 3 and 4 only
D 1, 2, 3 and 4

Q11. Anatomical dead space refers to:

A The volume of air that can be forcibly exhaled after a normal exhalation.
B The volume of air present in the conducting airways that does not participate in gas exchange.
C The volume of air remaining in the lungs after a maximal expiration.
D The volume of air that can be forcibly inhaled after a normal inhalation.

Q12. Consider the following partial pressures: P(O2) in alveolar air = 104 mmHg P(O2) in deoxygenated blood = 40 mmHg P(CO2) in alveolar air = 40 mmHg P(CO2) in deoxygenated blood = 45 mmHg Which of the following statements correctly describes the direction of gas exchange in the alveoli?

A Oxygen diffuses from alveoli to blood, CO2 diffuses from blood to alveoli.
B Both oxygen and CO2 diffuse from alveoli to blood.
C Oxygen diffuses from blood to alveoli, CO2 diffuses from alveoli to blood.
D Both oxygen and CO2 diffuse from blood to alveoli.

Q13. A person is voluntarily holding their breath. Which of the following would eventually force them to breathe again?

A An increase in lung stretch activating Hering-Breuer reflex.
B A decrease in arterial PO2 stimulating peripheral chemoreceptors.
C A decrease in venous PO2 stimulating medullary centers.
D An increase in arterial PCO2 and H+ stimulating the central chemoreceptors.

Q14. Which of the following structures is part of the conducting portion of the respiratory system but does not participate in gas exchange?

A Alveoli
B Respiratory bronchioles
C Terminal bronchioles
D Alveolar ducts

Q15. A person suffers from a condition where the respiratory membrane thickens due to fibrosis. Which of the following would be the most immediate and significant consequence?

A Decreased alveolar PO2.
B Enhanced oxygen carrying capacity of blood.
C Increased ventilation-perfusion ratio.
D Reduced rate of gas diffusion across the membrane.

Q16. A patient with emphysema experiences destruction of alveolar walls and loss of elasticity. Which of the following lung volumes or capacities would most likely increase significantly in this patient?

A Vital Capacity (VC)
B Inspiratory Reserve Volume (IRV)
C Expiratory Reserve Volume (ERV)
D Functional Residual Capacity (FRC)

Q17. Which of the following scenarios would lead to a rightward shift of the oxygen dissociation curve (ODC)? I. Increased pH II. Increased PCO2 III. Increased temperature IV. Increased 2,3-BPG concentration

A II, III, IV
B II, IV
C I, III, IV
D I, II, III

Q18. To maintain electrical neutrality during the transport of bicarbonate ions out of the red blood cells into the plasma at the systemic tissues, which ion moves into the red blood cells?

A K+
B Na+
C Cl-
D H+

Q19. If a person's blood pH decreases significantly, what effect would this have on the oxygen dissociation curve and subsequent oxygen release to tissues?

A Leftward shift; reduced oxygen release.
B Leftward shift; enhanced oxygen release.
C Rightward shift; enhanced oxygen release.
D No significant shift; oxygen release remains constant.

Q20. The primary function of epiglottis during swallowing is to:

A Prevent food from entering the larynx.
B Regulate the rate of breathing.
C Facilitate the movement of air into the trachea.
D Produce sound during speech.

Biology — Mock Test

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