What is one use of glucose?

a. to power photosynthesis
b. to make cellulose in the cell walls
c. to make cell membranes
d. to capture sunlight

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link:

b is dominant over the allele for the white fur.

the answer to your question is tooth decay.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.