The correct option is 2 and 3 only.
Explanation
Digestion in the small intestine relies on secretions from the liver (bile) and the pancreas (pancreatic juice). These secretions interact with the partially digested food (chyme) received from the stomach to facilitate the chemical breakdown of macromolecules like fats, proteins, and carbohydrates.
Statement-wise Analysis
- Statement 1 is Incorrect: The food entering the small intestine from the stomach is highly acidic due to the presence of hydrochloric acid. However, pancreatic enzymes require an alkaline medium to function optimally. Bile, secreted by the liver, is alkaline in nature. It neutralizes the acidic chyme and creates the necessary alkaline environment for enzymatic action, rather than making it acidic.
- Statement 2 is Correct: Fats are insoluble in water and enter the intestine as large globules. Bile contains bile salts (such as sodium glycocholate and sodium taurocholate) which act like detergents. They break down large fat globules into smaller globules, a process called emulsification. This significantly increases the surface area of the fats, making them more accessible to enzymes.
- Statement 3 is Correct: The pancreas secretes pancreatic juice containing various enzymes, including trypsin, amylase, and lipase. Lipase (specifically pancreatic lipase or steapsin) is the primary enzyme responsible for fat digestion. It acts efficiently on the emulsified fat globules to hydrolyze them into diglycerides and monoglycerides.
Key Takeaway: Bile does not contain any digestive enzymes; its primary roles are to provide an alkaline medium and to emulsify fats. The actual chemical breakdown of fats is performed by the enzyme lipase found in pancreatic juice.