Question

different l. lactis bacteria are better at fermenting different types of sugars. some l. lactis have polysaccharide - specific fermentation, so they can ferment large sugar molecules called polysaccharides but not a small sugar molecule called lactose. other l. lactis have lactose - specific fermentation; they can ferment lactose, which is found in milk, but cannot ferment polysaccharides. lactose - specific fermentation is useful for humans: it helps turn milk into cheese!
the l. lactis bacterias environment changed to have fewer polysaccharides than lactose sugars. after this change, over a time period long enough for natural selection to occur, the percentage of the l. lactis population with lactose - specific fermentation increased.
use the theory of natural selection to construct a possible explanation for how the l. lactis population adapted to its changed environment.
having lactose - specific fermentation was more advantageous than having polysaccharide - specific fermentation after the environment changed. so the alleles for polysaccharide - specific fermentation were passed on with frequency than the alleles for lactose - specific fermentation. as a result, the proportion of the population with polysaccharide - specific fermentation decreased. over time, the population adapted such that a higher percentage of bacteria were dependent on the less abundant sugar.

Explanation:

Natural selection favors traits that enhance survival and reproduction. With more lactose than polysaccharides, lactose - specific fermentation is advantageous. Bacteria with this trait reproduce more, passing on their alleles. Polysaccharide - specific alleles are less frequent as their carriers have fewer resources. Over time, the population shifts towards lactose - specific fermentation.

Answer:

lower