OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

How do proteins in the body get processed?

1. They are converted into sugars for immediate energy

2. They are stored in the liver indefinitely

3. Excess proteins are broken down and converted

4. They are used directly for muscle development

The correct answer is: Excess proteins are broken down and converted

Proteins in the body undergo a process known as protein metabolism, which involves the breakdown and utilization of proteins for various functions. When there is an excess of proteins that the body does not need for immediate use, they are broken down into their amino acids. This breakdown occurs primarily in the liver, where amino acids can then be transformed into other necessary compounds, stored as energy, or converted into different forms used by the body, including glucose through gluconeogenesis or fatty acids for long-term energy storage. This ability to break down excess proteins into useful products allows the body to maintain a balance and ensure that all necessary components are available for physiological functions, while also managing an excess that could potentially lead to toxicity. This aspect of protein processing underscores the importance of amino acids not just as building blocks for proteins, but also as versatile compounds that can be repurposed for energy or other metabolic pathways.