Oxygens percentage in the atmospheric air is that CO2 percentage and its solubility in solution (Example: Olood) is than CO2 solubility.

Correct Answer: B

Rationale: Atmospheric air has ~21% oxygen (O2) and ~0.04% carbon dioxide (CO2), so O2's percentage vastly exceeds CO2's, reflecting their natural abundances. Solubility, per Henry's law, depends on the solubility coefficient: O2's is ~0.024 ml/mmHg/L blood, while CO2's is ~0.51 ml/mmHg/L over 20 times higher. Thus, O2 is less soluble than CO2, despite its higher atmospheric presence. In blood, O2 relies on hemoglobin (~98% bound, ~2% dissolved), while CO2 uses dissolved (~7%), bicarbonate (~70%), and hemoglobin (~23%) forms, leveraging its solubility. Option B (higher O2 percentage, lower O2 solubility) fits: 21% vs. 0.04%, and 0.024 vs. 0.51. This contrast drives distinct transport mechanisms O2's hemoglobin dependence vs. CO2's solubility advantage crucial for respiration and acid-base balance, making it the accurate physiological description.

Correct Answer: A

Rationale: Work of breathing (WOB) is energy to overcome elastic (compliance) and resistive (airway) forces. Compliance (C = ΔV / ΔP) measures lung stretchability low C (stiff lungs) raises pressure needed, increasing WOB; thus, WOB is inversely related to compliance, true. During exercise, WOB rises with ventilation demand, not constant false. Airway resistance (R) directly increases WOB (e.g., asthma), contradicting not affected' false. In pulmonary fibrosis, low compliance elevates WOB, not reduces it false (emphysema might lower elastic work). The inverse compliance link (WOB = ∫P dV, P rises as C falls) is fundamental, reflecting effort to expand stiff lungs, making it the correct statement, critical for understanding respiratory workload in disease.

Correct Answer: D

Rationale: Inhalation sequence: (5) Diaphragm and intercostals contract, expanding the thorax. (1) Intrapleural pressure drops from -4 mmHg (756 mmHg) to -6 mmHg (754 mmHg), increasing transpulmonary pressure. (3) Lungs expand. (4) Intra-alveolar pressure falls to 759 mmHg (-1 mmHg) per Boyle's law, creating a gradient. (2) Air flows in. Order 5,1,3,4,2 reflects causality: muscle action lowers IPP, expands lungs, drops alveolar pressure, drives airflow. Others disrupt e.g., 5,2,3,4,1 puts flow before pressure; 1,3,4,5,2 starts without muscle action. This aligns with respiratory mechanics, ensuring logical progression for tidal breathing (~500 ml).

Correct Answer: B

Rationale: Nitrogen (N2) is the most abundant gas in Earth's atmosphere, comprising ~78% by volume, due to its chemical stability and geological accumulation. Oxygen (O2) is ~21%, vital for life but secondary. Argon (~0.93%) and carbon dioxide (CO2, ~0.0407%) are trace gases, with CO2 critical for climate despite low abundance. Nitrogen's dominance results from its inert nature and massive release during Earth's formation, per atmospheric composition data (e.g., NOAA). It dilutes other gases, shaping atmospheric pressure (~1013 hPa), making it the correct choice, far exceeding oxygen or trace constituents in prevalence.

Correct Answer: B

Rationale: The lateral nasal wall receives sensory innervation from trigeminal branches. The anterior ethmoidal nerve (A, V1) supplies the anterior upper part, the anterior palatine (C, greater palatine, V2) the posterior lower part, and the posterior superior lateral nasal nerve (D, V2) the posterior upper region. The posterior ethmoidal nerve (B, V1) innervates the posterior ethmoidal sinuses and upper nasal septum, not the lateral wall, which is served by other branches. Its role is sinus-specific, making B the exception.