When cool air sinks it forces warm air to rise is a example of convection.
Answer:
The correct answer is "the S layer may play a role in protecting cells from viruses and predatory bacteria found in nature but not in laboratory cultures".
Explanation:
The S-layer (surface layer) is a part of the cell's envelope comprised of of identical proteins or glycoproteins that could be found in archaes and some bacterias in nature. The function of the S-layer is unknown, however the fact that is only seen in nature suggest that it may play a role in protecting cells from viruses and predatory bacteria found in nature but not in laboratory cultures. It is likely that archaes and bacteria synthesize the S-layer when they recognize viruses and predatory bacteria in nature, the S-layer is not synthesized in laboratory cultures because these pathogens are not present.
