Which of the following is true of sickle cell disease?
a. it shortens the life span of red blood cells
b. it causes blood cells to clump together in small blood vessels
c. it damages the spleen
d. all of these
Question 2
A point mutation occurs when __________ is changed.
a. a single gene
b. an allele pair is changed
c. an introns is changed
d. a single base in a gene
