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 the next row of circles and squares which are the offspring. Starting from the left an unshaded square, half-shaded circle, another half-shaded circle and a completely shaded square are shown. All these are also connected by a horizontal straight line. What percentage of the offspring have sickle cell anemia? 0% 25% 50% 100%

25%

Explanation:

From the description;

The parents: half shaded circle and square = heterozygous parents

The offspring:

unshaded square = homozygous normal

half shaded circle = heterozygous normal

half shaded circle = heterozygous normal

completely shaded square = affected (homozygous abnormal)

The unshaded and half shaded offspring are normal and do not have sickle cell anemia. The completely shaded square represents a male offspring with sickle cell anemia.

Out of 4 offspring, 1 is affected for sickle cell anemia. Hence the percentage of the offspring that have sickle cell anemia is 25%.

a axis of a graph is a color or shade so we can all go outside and have a party so we can eat   some grilled cheese sammiches and broccoli and have some ugly fun times

i don't know why i put this, i know its not the i was just bored : p

delete this answer while you can