USA Biology Olympiad (USABO) Practice Exam

What is the main function of the cell wall in bacteria and fungi?

1. To protect against viruses

2. To provide structure and support

3. To facilitate cellular communication

4. To aid in photosynthesis

The correct answer is: To provide structure and support

The main function of the cell wall in both bacteria and fungi is to provide structure and support. In bacteria, the cell wall is primarily composed of peptidoglycan, which creates a rigid framework around the cell. This structure helps maintain the shape of the cell, protects it from osmotic pressure, and acts as a barrier against certain environmental stresses. In fungi, the cell wall is mainly composed of chitin, along with other polysaccharides. This also provides structural integrity and strength, allowing fungi to thrive in various environments. The rigidity afforded by the cell wall is crucial for maintaining the overall shape of the organism and protecting it from mechanical damage. The roles attributed to structuring and supporting the cell wall make it essential for both growth and survival, distinguishing it from the other options that do not capture the primary function of the cell wall in these organisms. Although the cell wall may indirectly influence cellular communication or protect against certain pathogens, these are not its principal functions compared to the crucial need for structural stability.