Which of the following is an example of a storage form of glucose in the human body?
A.
Starch.
B.
Glycogen.
C.
Fructose.
D.
Cellulose.
The Correct Answer and Explanation is:
The correct answer is B. Glycogen.
Explanation:
Glycogen is the primary storage form of glucose in the human body. When we consume carbohydrates, they are broken down into glucose, which is then absorbed into the bloodstream. The body uses glucose as an immediate energy source, but when the energy demand is low, the excess glucose is stored for future use. Glycogen, a polysaccharide, serves as this storage form and is primarily found in the liver and skeletal muscles.
- Glycogen Structure and Function: Glycogen is a highly branched molecule composed of many glucose units linked together. The branched structure allows for rapid release of glucose when energy is needed. The liver stores glycogen to maintain blood glucose levels, especially between meals or during fasting. Muscle glycogen, on the other hand, is used locally by muscles to generate energy during physical activity.
- Comparison with Other Options:
- Starch (Option A) is the storage form of glucose in plants, not humans. Humans consume starch from foods like potatoes and grains, but it is broken down into glucose during digestion before being stored as glycogen in the body.
- Fructose (Option C) is a simple sugar found in fruits and honey. It is not a storage form but rather a type of sugar that can be converted into glucose in the liver or used directly for energy.
- Cellulose (Option D) is another polysaccharide found in plants, but it serves a structural role rather than an energy storage role. Humans cannot digest cellulose because they lack the necessary enzyme to break its beta-glycosidic bonds, making it an indigestible form of fiber in the diet.
- Importance of Glycogen: Glycogen plays a crucial role in energy management in the body. During periods of low blood sugar, such as between meals or during intense exercise, glycogen is broken down into glucose through a process called glycogenolysis. This process ensures a steady supply of glucose for vital organs, particularly the brain, which relies heavily on glucose as its primary energy source.
In summary, glycogen is the key storage form of glucose in humans, ensuring that the body has a readily available energy source during times of need. Understanding this concept is fundamental in fields such as nutrition, physiology, and medicine.