Which of the following biomolecules is known for serving as a primary energy source for cells?

• A. Proteins
• B. Nucleic acids
• C. Carbohydrates
• D. Lipids

Answer: (C)

Carbohydrates are known as the primary energy source for cells due to their structure and metabolism. They are made up of carbon, hydrogen, and oxygen, commonly in a ratio of 1:2:1. Simple carbohydrates, like glucose, are easily broken down by the body to produce ATP (adenosine triphosphate), which is the main energy currency of cells.

When carbohydrates are consumed, they undergo digestion and are transformed into glucose, which can be used immediately for energy or stored as glycogen for later use. This efficient conversion and storage system makes carbohydrates the go-to source for quick energy.

While other biomolecules like proteins and lipids also serve roles in energy production and storage, they are not the preferred source. Proteins primarily function as building blocks for tissues and have a more complex metabolic pathway that is not used for immediate energy needs. Lipids are important for long-term energy storage and insulation but are metabolized at a slower rate compared to carbohydrates. Nucleic acids, on the other hand, are primarily involved in genetic information storage and transfer rather than energy production.

Thus, carbohydrates play a crucial role as the primary and most readily available energy source for cellular activities.