Question

The food tastes sour when

• A. Hydrogen ion pass through the same channel as that of the sodium ion
• B. Hydrogen ion blocks the potassium channel
• C. Hydrogen ion blocks the calcium channel
• D. Both A and B

Answer 1

The correct option is D Both A and B

The sour taste originally comes from acidic foods, in which their molecules dissociate into proton/positive hydrogen ions. Common chemical molecules that dissociate into hydrogen ions to characterize a sour or tangy taste are carboxylic acids which have a distinctive carboxyl functional group, -COOH. The hydrogen proton of acids and sour foods can influx through the Na${}^{+}$ channels, or through a proton transport membrane protein. Some acids block the efflux of K${}^{+}$ at the microvilli. The resulting influx of protons or a reduction in K${}^{+}$ conductance will initiate receptor potentials in response to the quality of sour tastes.

So, the correct answer is option D.