. What is the role of acid in our stomach
A: Acidify the food for proper action of pepsin
B: Conversion of pepsinogen and prorenin into active forms of pepsin and rennin
C: Killing of microorganisms present in food
D: All of the above
HCl acid is secreted from the parietal cells present in the mucosa layers.
This acid converts the proenzyme pepsinogen and prorennin into their active forms pepsin and rennin respectively.
Pepsin is needed for the digestion of proteins to proteoses and peptones.
Rennin is present in infants for the digestion of milk proteins.
This acid mixes thoroughly with the food, lowering the pH for the activity of pepsin.
Lower pH kills the microorganisms present in the food.
Hence the correct answer is D i.e. all of the above.