_____is the most abundant organic compound on Earth.
- Starch
- Lactose
- Glucose
- Cellulose
- Glycogen
The correct answer and explanation is :
The correct answer is 4. Cellulose.
Cellulose is the most abundant organic compound on Earth, making up approximately 33% of all plant matter. It is a complex carbohydrate (polysaccharide) composed of long chains of glucose molecules, specifically β-glucose, linked together through β-1,4-glycosidic bonds. This molecular structure gives cellulose its rigidity and strength, which is essential for providing structural support to plant cells.
Cellulose is a major component of the cell walls of plants, algae, and some bacteria, allowing them to maintain their shape and resist external pressures. The high abundance of cellulose is largely due to the extensive presence of plants on Earth, which rely on cellulose to maintain their integrity. Wood, cotton, and other plant fibers are primarily composed of cellulose, and it is also found in the cell walls of other plant structures, such as leaves and stems.
One of the reasons cellulose is so abundant is that plants produce it during photosynthesis, using carbon dioxide from the atmosphere and energy from sunlight. It serves as a key structural component, and its role in photosynthesis is critical for maintaining the balance of carbon in the environment.
Despite its abundance, humans cannot digest cellulose due to the lack of the necessary enzymes (cellulases) to break down the β-glycosidic bonds. However, cellulose plays a vital role in the diet as fiber, promoting digestive health by adding bulk to stool and assisting in regular bowel movements.
In contrast, other options like starch, lactose, glucose, and glycogen are also organic compounds, but they are not nearly as abundant as cellulose. Starch is the primary energy storage polysaccharide in plants, while glucose is a simple sugar, and glycogen serves as the energy storage form in animals. Lactose is a disaccharide found in milk. None of these compounds are as widely distributed in nature as cellulose.