What is the function of a capsule in certain bacteria?

The function of a capsule in certain bacteria is to protect the cell surface and assist in adhering to surfaces. Capsules are composed of polysaccharides or proteins and form a thick protective layer around the bacterial cell wall. This structure serves multiple purposes: it helps to prevent desiccation, protects against phagocytosis by immune cells, and contributes to the bacterium's ability to adhere to surfaces, which is especially important in the establishment of infections. The presence of a capsule can enhance a bacterium’s virulence by making it more difficult for the host's immune system to eliminate the pathogen.

The other options describe functions that are attributed to different cellular structures or processes, not the capsule. Storing genetic material is a function associated with the bacterial chromosome or plasmids. Providing energy is primarily a function of metabolic processes occurring within the cell, and regulating nutrient uptake is managed by various mechanisms through the cell membrane rather than by the capsule.