Which statement about carbohydrate function is correct?

• A. They serve as genetic material
• B. They provide cell energy in the form of glucose
• C. They catalyze chemical reactions as enzymes
• D. They are the primary components of cell membranes

Answer: (B)

The main idea here is that carbohydrates primarily provide energy for cells, with glucose acting as the immediate fuel. In cellular respiration, glucose is broken down through glycolysis, the citric acid cycle, and oxidative phosphorylation to make ATP, the cell’s main energy currency. Because glucose can be rapidly catabolized to generate ATP, carbohydrates are the body’s quick source of energy. Plants store energy as starch and animals store it as glycogen, ready to be mobilized when needed.

Carbohydrates aren’t the genetic material (that’s the role of nucleic acids like DNA and RNA). They aren’t enzymes that catalyze reactions (those are proteins, and in some cases RNA can have catalytic roles). And the primary components of cell membranes are phospholipids, with proteins and lipids forming the bilayer structure; carbohydrates do appear on the membrane surface as glycolipids and glycoproteins, but they aren’t the main structural components.