The studies are designed this way b/c it removes the power of suggestion and the double-blind study keeps both researchers and participants in the dark. So this compared to who is receiving the treatment which is relevant b/c it stops the researchers from accidentally overbalancing the study participants, or unintentionally favoring their assessment of the conclusions.
The information that bacteriophage cocktail significantly reduces contamination of lettuce and beef with Escherichia coli o157:h7, but does not protect against recontamination was demonstrated by the group of scientists. The suggest that this might be due to unsanitary handling of the foods post processing.
Isn't it the cell membrane? The cell membrane controls what goes in and out of the cell using active and passive transport. Osmosis being a part of passive transport.