The human oral microbiota contains over 700 species of bacteria. One species often found in the oral cavity is Streptococcus mutans, an anaerobic bacterium strongly associated with the formation of dental cavities. S. mutans metabolizes glucose and other dietary sugars remaining in the mouth after a meal, producing lactic acid as a byproduct. Over time, high levels of lactic acid can erode tooth enamel, eventually leading to the formation of dental cavities. Which of the following drugs would be most likely to prevent cavities caused by 5. mutans? A. A drug that inhibits the formation of a proton gradient across the cell membrane
B. A drug that prevents the conversion of glucose into pyruvate
C. A drug that inhibits the production of NADH and FADH2 during the Krebs cycle
D. A drug that prevents the movement of oxygen across the cell membrane

B. A drug that prevents the conversion of glucose into pyruvate

Explanation:

Streptococcus mutans is a facultatively anaerobic bacterium, i.e., a microorganism capable of producing ATP by both aerobic (when there is oxygen), and anaerobic (i.e., when there is no oxygen available) conditions. This bacterium is observed in the human oral cavity where causes the majority of tooth decay. S. mutans can digest carbohydrates (e.g. glucose, fructose and lactose) in order to produce lactic acid, which contributes to tooth decay. Glycolysis is the fermentation of glucose to pyruvate in anaerobic conditions, and thereby it is expected that a drug capable of preventing the conversion of glucose into pyruvate in anaerobic conditions is effective to prevent cavities caused by S. mutans.

d.

explanation:

air enters through the nose, moves through the nasal cavity, the pharynx, the larynx, enters the trachea, moves through the bronchi andbronchioles till the alveoli.