Question

The major site of protein breakdown to form free amino acids is in the
(a) Kidney
(b) Spleen
(c) Intestine
(d) Bone marrow

Answer 1

Hint: Protein is a very large nutrient that’s made up of smaller substances called amino acids. There are 20 amino acids, but your body can only make 9 of them. The other 11 are called essential amino acids.
From the stomach, smaller chains of amino acids move into the small intestine. As this happens, the pancreas releases enzymes and a bicarbonate buffer that reduces the acidity of digested food. This reduction allows more enzymes to work on further breaking down amino acid chains into individual amino acids.
Complete answer:
Protein absorption majorly happens in the small intestine, which contains microvilli. These are small, finger-like structures that increase the absorptive surface area of your small intestine. This allows for maximum absorption of amino acids and other nutrients.
Once they’ve been absorbed, amino acids are released into your bloodstream, which takes them to cells in other parts of your body so they can start repairing tissue and building muscle.
Kidney functions as a blood filtration tool which separates waste from the blood. The spleen is the site where blood is filtered as a part of the immune system, also recycling of old blood cells are done here. Bone marrow is the site where there is the formation of new blood cells. The intestine is the only place where the protein in ingested food is broken down into simple forms after the partial breakdown in the stomach. So major proteinaceous food is broken down into free amino acids in the intestine. 

Additional information: Some common enzymes involved in this phase include:
1. Trypsin
2. Chymotrypsin
3. Carboxypeptidase

So the correct answer is- C. Intestine

Note: The small intestine is the major site of protein digestion by proteases (enzymes that cleave proteins). The pancreas secretes a number of proteases as zymogens into the duodenum where they must be activated before they can cleave peptide bonds. This activation occurs through an activation cascade.