Question

Researchers have crossed two true-breeding lines of peas that differ in the color of their leaf tissue: dark green vs pale green. After selfing the resulting F1s to produce an F2 population, they characterized the phenotypes for 200 F2 individuals and report 122 dark and 78 pale plants. You want to test the for the possibility that the dark phenotype is determined by a dominant allele at a single locus. Using that as your null hypothesis, how many of the 200 F2 individuals would you have expected to be dark

Answer 1

150 individuals

Step-by-step explanation:

If the dark phenotype is determined by a dominant allele at a single locus, the ratio of dark green phenotype to pale green phenotype at F2 should be 3:1 according to the Mendelian standard.

200 to 3:1 = 150:50

Hence, if 200 F2 individuals were characterized, one would expect the number of dark green individuals to be 150 while the pale green would be expected to be 50.