Dominant & Recessive
Mendel began studying peas by observing traits like pea plant height, pea color, and pea shell smoothness. These characteristics are examples of phenotypes, a term used by geneticists to describe an observable trait.
Human traits include phenotypes such as height, eye color, blood pressure, and blood type.
In particular, Mendel was very interested in learning the ratio of plants with specific phenotypes. For example, one ratio he calculated was the number of plants with yellow peas to the number of plants with green peas. In this case, yellow and green are two phenotypes for the trait pea color.
Let's calculate the ratio of yellow to green peas that Mendel observed. Let's say he counted 1690 plants with green peas and 567 plants with yellow peas. What was the ratio of green : yellow peas that Mendel observed?
1 greenPeas = 1690
2 yellowPeas = 567