The functional unit of the kidney is: MCQ with Answer and Explanation

Explanation:
Vitamins are classified by their solubility. Vitamins A, D, E, and K are fat-soluble, meaning they are absorbed with dietary fats and can be stored in the body's liver and fatty tissues. Vitamins B-complex and C are water-soluble, meaning they dissolve in water and are generally not stored in significant amounts. Vitamin D (cholecalciferol) is unique because it can be synthesized endogenously in the skin when exposed to ultraviolet B (UVB) radiation from sunlight. All statements are correct.

Explanation:
The Loop of Henle is a U-shaped tube extending into the renal medulla. Its primary function is to concentrate the urine by creating a hyperosmotic gradient in the medullary interstitium through the counter-current multiplier mechanism. The descending limb is permeable to water but not salts, while the ascending limb is impermeable to water but actively transports salts out. This gradient allows the collecting duct to reabsorb water under the influence of ADH.

Explanation:
The adult human dental formula is 2123/2123 (incisors 2, canines 1, premolars 2, molars 3) per quadrant, totaling 32 permanent teeth. Deciduous teeth formula is 2102/2102 (20 teeth). The formula represents half of the upper jaw over half of the lower jaw. Wisdom teeth (third molars) may be absent in some individuals.