What do catabolic pathways primarily do?

• A. Convert energy into usable forms
• B. Break down complex molecules into simpler ones
• C. Synthesize molecules needed by the body
• D. Regulate hormonal activity

Answer: (B)

Catabolic pathways primarily function to break down complex molecules into simpler ones. This process is essential because it allows the body to release and harness energy from food and stored nutrients. When larger macromolecules like carbohydrates, fats, and proteins are broken down, they are converted into smaller units such as glucose, fatty acids, and amino acids, respectively. This breakdown not only provides energy for cellular activities but also generates metabolic intermediates that can be used in various biosynthetic pathways or for energy production in the form of ATP through cellular respiration.

In contrast, other pathways mentioned, such as those involved in synthesizing molecules (which are more aligned with anabolic pathways), do not focus on breaking down substances. Similarly, while energy conversion is part of the metabolic process, it does not capture the specific role that catabolic pathways play in degradation and energy release. The regulation of hormonal activity also is unrelated to the primary function of catabolic pathways, which is energy extraction and molecule simplification.