NEET Biology: transport of gases and regulation of respiration Practice Questions

Correct answer: B — Oxygen is primarily transported bound to hemoglobin in red blood cells.

Oxygen is overwhelmingly transported in the blood bound to hemoglobin molecules within red blood cells. This binding allows for efficient transport across the circulatory system.

Correct answer: B — Gas exchange

Respiration involves the intake and expulsion of gases (gas exchange). The regulation of respiration is fundamentally the regulation of the rate of gas exchange governed by the body's need for O2 and removal of CO2.

Correct answer: D — Hemoglobin

Hemoglobin, a protein found in red blood cells, binds reversibly with oxygen and is the most crucial carrier of O₂ in the blood.

Correct answer: D — Bicarbonate ions (HCO₃⁻)

Approximately 70% of CO₂ is transported in the blood as bicarbonate ions (HCO₃⁻), which is transported via the circulatory system.

Correct answer: A — PO₂ is lower in the venous blood than in the alveolar air.

In the pulmonary capillaries, oxygen moves from the alveoli (high PO₂) into the blood, and carbon dioxide moves from the blood into the alveoli. Therefore, the partial pressure of oxygen (PO₂) in the venous blood is lower than the partial pressure of oxygen in the alveolar air, and conversely, the partial pressure of carbon dioxide (PCO₂) in the venous blood is higher than in the alveolar air.

Correct answer: D — Concentration difference

Gas exchange (diffusion) across the respiratory membrane is fundamentally driven by the difference in partial pressure of the gases between the alveolar air and the pulmonary capillary blood.

Correct answer: C — Diffusion

Gas exchange across the alveolar and capillary walls occurs due to the difference in partial pressure of gases, following the principle of diffusion.

Correct answer: B — Alveolar walls

The alveolar walls, in conjunction with the capillary walls, form the respiratory membrane, which is the site where the diffusion of oxygen and carbon dioxide occurs between the air in the alveoli and the blood in the capillaries.

Correct answer: D — Breathing rate increases

Increased CO2 leads to increased acidity (lower pH), which stimulates chemoreceptors, prompting an increase in the rate and depth of breathing (ventilation) to expel the excess CO2.

Correct answer: D — Regulation by the respiratory centers in the brainstem

The fundamental rhythm and rate of breathing are controlled by the respiratory centers located in the medulla oblongata and pons of the brainstem, which process sensory input to adjust ventilation.

Correct answer: C — Partial pressures of gases

Gas exchange is driven by the difference in partial pressures of the gases (e.g., P₍O2) and P₍CO2)) across the alveolar and capillary membranes.

Correct answer: B — As bicarbonate ions (HCO₃⁻)

Approximately 70% of CO₂ is transported in the blood as bicarbonate ions (HCO₃⁻), which is crucial for the blood's buffering system.

Correct answer: B — Decreased arterial P₍CO2)

Increased ventilation causes more O₂ to enter the lungs and more CO₂ to be expelled, leading to an increase in the arterial partial pressure of oxygen (P₍O2)).

Correct answer: D — Carbon dioxide

Carbon dioxide is the waste product of cellular respiration and is transported from the tissues to the lungs via the blood, moving from areas of high partial pressure to low partial pressure.

Correct answer: C — Pressure

Gas exchange, including oxygen uptake, occurs via simple diffusion, which is driven by the difference in partial pressures of the gases across the alveolar and capillary walls.