The structure in the kidney that concentrates urine is the: MCQ with Answer and Explanation

Explanation:
Enzyme activity depends on pH and temperature; they are not consumed (reusable). Optimum temperature varies; human enzymes around 37°C, but bacterial enzymes can be higher. So 2 is not universally true.

Explanation:
The retina is the inner lining of the eye containing rods and cones, the photoreceptor cells for vision. The cochlea is a spiral-shaped cavity in the inner ear containing the organ of Corti, essential for converting sound vibrations into nerve impulses. Taste buds are primarily on the tongue but are also found on the soft palate, epiglottis, and upper esophagus. Thus, statements 1 and 2 are correct.

Explanation:
Vitamin B₆ exists in three forms: pyridoxine, pyridoxal, and pyridoxamine. Its active form, pyridoxal phosphate (PLP), is a coenzyme in amino acid metabolism and neurotransmitter synthesis. Deficiency can cause peripheral neuropathy and anemia.