DQ19: A pea plant must have exactly one of each of the following pairs of traits: Short (s) or tall (t); round (r) or wrinkled (w) seeds; yellow (y) or green (g) peas; and white (wh) or purple (p) flowers. For example, a pea plant can be short with wrinkled seeds, green peas and white flowers. How many different classifications of pea plants are possible

There are 16 possible different classifications of pea plants.

Explanation:

In order to get the number of classifications, you must multiply all the possibilities by each other in each trait. This is, each trait has two states (short or tall, round or wrinkled, yellow or green, white or purple) and are referred to as "pair of traits". These must be multiplied with the other pairs of traits. So, the number of different classifications of pea plants is:

the number of high states x number of shape states x number of peas color sates x number of flower color states = 2 x 2 x 2 x 2 = 16.