HELP. Sickle cell anemia is known to run in a family. A pedigree chart for this family is shown below.

The parents are shown at the top and from left to right appear as a half-shaded circle next to a half-shaded square. The two are connected by a straight line. Below the parent pair is a vertical straight line connecting to the next row of circles and squares which are the offspring. Starting from left an unshaded square, half-shaded circle, another half-shaded circle, and a completely shaded square are shown. All of these are also connected by a horizontal straight line .(or look at picture)

What percentage of the offspring have sickle cell anemia?
0%
25%
50%
100%

Ry was studying two populations of the same species of lizards. one population lived on an island and the other lived on the mainland. both populations were affected by a hurricane that hit the island and the mainland with equal force. a year later, henry was testing the gene frequency and saw a decrease in genetic variation in the island species, but not in the mainland species. which best describes a conclusion he might have reached? gene flow greatly affects small populations, but large populations can recover. genetic drift greatly affects small populations, but large populations can recover. gene flow greatly affects large populations, but small populations can recover. genetic drift greatly affects large populations, but small populations can recover.

Compare the composition of the moon's surface with the composition of the earth's surface.

In the diagram below, the northern hemisphere would be in what season at position a a. fall b. winter c. summer d. spring