What is composed of polymers of amino acids and is essential for the growth and repair of tissues?

The correct answer is protein because proteins are large molecules made up of long chains of amino acids, which are the building blocks of proteins. These polymers of amino acids fold into specific three-dimensional shapes that determine their function in the body. Proteins play a crucial role in the growth and repair of tissues, as they are essential components of muscles, skin, enzymes, hormones, and many other bodily structures and functions.

In contrast, lipids are primarily involved in energy storage and cell membrane structure rather than directly contributing to tissue growth and repair. Carbohydrates are mainly a source of energy for the body and, while they are important for overall health, they do not provide the structural components necessary for tissue repair. Vitamins are organic molecules that support various bodily functions but are not composed of amino acids and do not play a direct role in growth and repair processes. Thus, proteins uniquely fulfill the requirement of being composed of amino acids and are essential for the growth and repair of tissues.