What new piece of evidence, supporting biogenesis, was provided by pasteur's experiment? a) s-necked flasks prevented both microorganisms from contaminating the broth and air from entering the flasks. b) s-necked flasks prevented microorganisms from contaminating the broth, even though air still entered the flasks. c) pasteurs experiments with s-necked flasks supported the hypothesis that microorganisms are not found in the air. d) pasteur set up an experiment with both open and sealed flasks, thus employing a control or standard of comparison.