Why are fructose & galactose converted into glucose in the liver?

• A. Fructose & galactose are too large to be used by the body's cells; glucose is much smaller.
• B. Glucose is the body's preferred energy source - especially for red blood cells & nervous tissue.
• C. Having too much fructose & galactose in the blood stream causes blood pH to decrease (ketoacidosis).
• D. All of the above.

Answer: (B)

Verified step by step guidance

1. Understand the role of glucose as the body's preferred energy source, particularly for red blood cells and nervous tissue. Glucose is essential for these cells because they rely on it for ATP production through glycolysis.
2. Recognize that fructose and galactose are metabolized in the liver to be converted into glucose. This process ensures that the body has a consistent supply of glucose for energy needs.
3. Learn about the metabolic pathways involved: Fructose is converted into intermediates of glycolysis (such as fructose-1-phosphate) and eventually into glucose. Galactose is converted into glucose-6-phosphate through the Leloir pathway.
4. Understand the potential consequences of having excess fructose and galactose in the bloodstream. These sugars can disrupt normal metabolic processes and lead to conditions like ketoacidosis, which lowers blood pH and can be harmful to the body.
5. Conclude that the conversion of fructose and galactose into glucose in the liver is a critical process to maintain metabolic balance, provide energy to cells, and prevent harmful effects like blood pH imbalance.