How is it possible that some strains of staphylococcus aureus can be harmless, but others can be deadly?

This is due to mutation of the gene that is associated with its virulence. This mutation causes a mild strain to become a wild type. Some of these mutations are caused by the increased use and misuse of antibiotics. This also makes the Staph gain resistance against antibiotics and become deadly.

the potatoes have high sugar concentrations and although these potatoes were different we could seethe effects that their sugar concentrations had in different environments. for example, the potatoes in sample a, were placed in pure water. this created a hypertonic environment and caused the potatoes to draw in water from its surroundings. we saw the opposite happen with the potatoes in sample b when placed in the sodium chloride solution. the potatoes in this case were in a hypotonic solution and therefore lost water to their surroundings.