Which of the following carbohydrates found in food can be used as energy sources by living organisms?

• A. Deoxyribose
• B. Glucose
• C. Cellulose
• D. Chitin

Answer: (B)

Verified step by step guidance

1. Understand the role of carbohydrates in living organisms: Carbohydrates are organic molecules that serve as a primary energy source for cells. They can be broken down during cellular respiration to release energy in the form of ATP.
2. Analyze the given options: Deoxyribose, Glucose, Cellulose, and Chitin. Determine which of these carbohydrates can be metabolized by living organisms to produce energy.
3. Evaluate Deoxyribose: Deoxyribose is a sugar found in DNA and is not used as an energy source. It serves a structural role in nucleic acids rather than being metabolized for energy.
4. Evaluate Glucose: Glucose is a monosaccharide and a primary energy source for most living organisms. It is readily metabolized during glycolysis and subsequent steps of cellular respiration.
5. Evaluate Cellulose and Chitin: Both are polysaccharides with structural roles. Cellulose is found in plant cell walls, and chitin is found in the exoskeletons of arthropods. Most organisms cannot break down these molecules for energy due to the lack of specific enzymes, although some specialized organisms (e.g., certain bacteria) can.