Final answer:
The breakdown of food proteins into amino acids, which are then used to build new proteins in the body, is an example of metabolism, the set of life-sustaining chemical reactions in organisms.
Step-by-step explanation:
Food Proteins and Human Life Processes
Proteins are essential nutrients that are required for the proper functioning of our bodies. When we eat foods that contain protein, such as meat, milk, eggs, beans, and fish, these proteins are broken down into their component amino acids during the process of digestion. The amino acids are then absorbed into our blood and cells from the digestive system. In our cells, they serve as the building blocks for the synthesis of new proteins that become integral parts of our bodies, from muscle fibers to enzymes that regulate bodily functions.
The breakdown of food proteins into amino acids and the subsequent use of those amino acids to build new proteins is an example of metabolism. Metabolism includes all the biochemical processes that occur within a living organism, including the digestion of food and the synthesis of new cellular components. Hence, the correct answer to the question is (d) metabolism, as this is the human life process that describes the transformation of food protein into body protein. Proteins also have the responsibility for maintaining and repairing cells, fighting infections, and various other critical physiological functions.
It is important to note that there are twenty different amino acids that can be arranged in various ways to form proteins, and the human body can synthesize all but eight of these. The eight amino acids that cannot be synthesized by the body are known as essential amino acids, which must be obtained through our diet.