Saliva plays several important roles in our mouth, but one of the options listed is not one of its functions. Let’s break down each choice:
- a) Cleans the mouth: Saliva helps wash away food particles and bacteria, contributing to oral hygiene.
- b) Contains amylase and lipase: Saliva indeed contains the enzyme amylase, which starts the digestion of carbohydrates, and lipase, which begins fat digestion.
- c) Needed for the sensation of taste: Saliva is crucial for taste sensation as it dissolves food particles, allowing them to interact with taste receptors.
- d) Contains mucus to lubricate the food: Saliva does contain mucin, a glycoprotein that lubricates food, making it easier to swallow.
- e) Begins the digestion of proteins: This option is incorrect. While saliva has enzymes for carbohydrates and fats, it does not contain enzymes that initiate protein digestion.
Therefore, the correct answer is e) begins the digestion of proteins, as saliva is not involved in protein digestion.