What needs to be in place for natural selection to happen?

Spherocytosis is an inherited blood disease in which the erythrocytes (red blood cells) are spherical instead of biconcave. this condition is inherited in a dominant fashion, with sph- dominant to sph+. in people with spherocytosis, the spleen "reads" the spherical red blood cells as defective, and it removes them from the bloodstream, leading to anemia. the spleen in different people removes the spherical erythrocytes with different efficiencies. some people with spherical erythrocytes suffer severe anemia and some mild anemia, yet others have spleens that function so poorly there are no symptoms of anemia at all. when 2400 people with the genotype sph- sph+ were examined, it was found that 2250 had anemia of varying severity, but 150 had no symptoms. does this description of people with spherocytosis represent incomplete penetrance, variable expressivity, or both? explain your answer. (3 points)

Describe some of the common health conditions associated with air pollution.

Which of the following statements is true? a. poll data show that a majority of americans accept gay and b. open discussions of sexuality are welcomed by all families, c. homophobic stereotypes rarely occur in the media anymore. lesbian relationships. religious grougs, and social networks. d. poll data show that bisexuality and homosexuality are viewed positively by all parts of society