Regarding physiological dead space, one of the following is wrong?

Correct Answer: D

Rationale: Physiological dead space (VDphys) comprises anatomic dead space (VDanat, ~150 ml, airways) and alveolar dead space (VDalv, non-perfused alveoli). Normally, VDphys ≈ VDanat, but in disease, it's ≥ VDanat due to added VDalv true. Lung diseases (e.g., PE) increase VDphys via VDalv true. High V/Q (ventilation > perfusion, e.g., PE) raises VDphys, as ventilated alveoli lack blood flow true. However, VDphys isn't just alveolar dead space; it's VDanat + VDalv, so equating it to VDalv alone is wrong, omitting the anatomic component always present. This misdefinition skews VDphys's scope, critical for assessing total ventilatory waste, not just alveolar inefficiency, making it the false statement amid accurate descriptions.

Correct Answer: B

Rationale: Solar radiation is the primary energy source for Earth's climate system, delivering ~1361 W/m² at the top of the atmosphere (solar constant), driving weather, ocean currents, and the hydrologic cycle. Geothermal heat (~0.087 W/m²) from Earth's core is minor, mainly affecting tectonics, not climate. Tidal forces from the Moon influence oceans but provide negligible energy for climate. Cosmic background radiation (~2.7 K, microwaves) is far too weak. Solar energy's dominance is evident ~99.97% of climate energy comes from the Sun, absorbed and redistributed via atmosphere and surface processes (e.g., albedo, greenhouse effect), making it the fundamental driver, per climate science (e.g., IPCC), distinguishing it from trivial contributors.

Correct Answer: C

Rationale: A lower tracheostomy involves an incision below the thyroid isthmus, typically between the 2nd and 4th tracheal rings, to create an airway. The superior thyroid artery (A) arises from the external carotid and supplies the upper thyroid, far from this site. The inferior thyroid artery (B), from the thyrocervical trunk, supplies the lower thyroid and lies posterior, near the recurrent laryngeal nerve, but is less exposed. The inferior thyroid veins (C) drain the thyroid plexus into the brachiocephalic veins, running anteriorly across the trachea, making them highly vulnerable during midline incision. The internal jugular vein (D) lies lateral, near the carotid sheath, and is less at risk unless the incision deviates significantly. Anatomical variations (e.g., a thyroid ima artery) exist, but C is the most consistently endangered due to its anterior position and delicate nature.

Correct Answer: A

Rationale: True vocal cords are formed by the vocal ligament (cricovocal membrane) and vocalis muscle, a part of the thyroarytenoid (A), which adjusts tension and adducts cords. Cricothyroid (B) tenses cords externally, thyrohyoid (C) elevates the larynx, and transverse arytenoid (D) adducts arytenoids, but only A directly integrates into the cord structure.

Correct Answer: A

Rationale: Goblet cells (A) are unicellular glands in respiratory and intestinal epithelia, secreting mucus to trap particles and lubricate surfaces. Serous cells (B), in salivary glands, produce watery, enzyme-rich secretions, not thick mucus. Parietal cells (C) in the stomach secrete hydrochloric acid, aiding digestion, not mucus. Chief cells (D) release pepsinogen, a digestive enzyme precursor, not mucus. A is correct goblet cells' mucin-filled vesicles distinguish them as mucus producers, unlike the others, which have specialized secretory roles unrelated to mucus production.