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 labeled 1 next to a half-shaded square labeled 2. 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 labeled 1, half-shaded circle labeled 2, another half-shaded circle labeled 3, and a completely shaded square are shown labeled 4. all of these are also connected by a horizontal straight line. what best describes offspring 4?

In a pedigree chart, male is represented by a square and female a circle. Different generations in a family are lined up with the oldest at the top.  Shading represents the disease with half shade means a carrier and full shade means having the disease.

Based on the description, offspring 4 is represented by a completely shaded square so he is a male with sickle cell anemia.

2. it might continue expanding forever

Explanation:

If the ratio is greater than one, then the actual density of the Universe is greater than the critical density, and thus the Universe will eventually become closed and will ultimately end up collapsing in on itself. If the ratio is less than one, then the actual density is less than the critical density, and the Universe is open and expands forever in every direction