Among native Americans, two types of earwax (cerumen) are seen, dry and sticky. A geneticist studied the inheritance of this trait by observing the types of offspring produced by different kinds of matings. He observed the following numbers:
Parents Number of mating pairs Offspring
Sticky Dry
Sticky × sticky 10 32 6
Sticky × dry 8 21 9
Dry × dry 12 0 42
a. How is earwax type inherited?
b. Why are there no 3:1 or 1:1 ratios in the data shown in the chart?
