Question

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 □ 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 □. over time, the population adapted such that a □ percentage of bacteria were dependent on the less abundant sugar.

Explanation:

1. After the environment change (fewer polysaccharides, more lactose), lactose - specific fermentation is more advantageous (since lactose is more available). So the first blank: "more" (because being able to ferment lactose helps survival/reproduction better now).
2. Alleles for polysaccharide - specific fermentation: since lactose - specific is more advantageous, polysaccharide - specific alleles are passed on with "lower" frequency (because bacteria with polysaccharide - specific fermentation are less successful in survival/reproduction, so their alleles are less likely to be passed on).
3. Proportion of population with polysaccharide - specific fermentation: as their alleles are passed on less, their proportion "decreased" (natural selection favors lactose - specific, so the other type becomes less common).
4. Percentage of bacteria dependent on less abundant sugar (polysaccharides): since polysaccharides are less abundant and their - specific fermentation is less advantageous, the percentage of bacteria dependent on it is "lower" (because natural selection reduces the number of bacteria that rely on the less available and less favorable sugar).

Answer:

1. more
2. lower
3. decreased
4. lower