Question

The nutrient which acts as a fuel for living organism is

Answer 1

Answer:

carbohydrates and proteins

please recheck

Answer 2

Answer: Carbohydrates

Explanation:

Carbohydrates, lipids, and proteins are the major constituents of foods and serve as fuel molecules for the human body. The digestion (breaking down into smaller pieces) of these nutrients in the alimentary tract and the subsequent absorption (entry into the bloodstream) of the digestive end products make it possible for tissues and cells to transform the potential chemical energy of food into useful work.

The major absorbed end products of food digestion are monosaccharides, mainly glucose (from carbohydrates); monoacylglycerol and long-chain fatty acids (from lipids); and small peptides and amino acids (from protein). Once in the bloodstream, different cells can metabolize these nutrients. We have long known that these three classes of molecules are fuel sources for human metabolism, yet it is a common misconception (especially among undergraduates) that human cells use only glucose as a source of energy. This misinformation may arise from the way most textbooks explain energy metabolism, emphasizing glycolysis (the metabolic pathway for glucose degradation) and omitting fatty acid or amino acid oxidation. Here we discuss how the three nutrients (carbohydrates, proteins, and lipids) are metabolized in human cells in a way that may help avoid this oversimplified view of the metabolism.