Which part of the cell membrane acts as a barrier to hydrophilic molecules entering the cell?

Prior to the development of dna fingerprinting, blood type could be used to determine possible parentage. although it might prove someone was not a parent, it could not show if someone was positively the parent, only that he or she might be a parent. which of the following is a true statement that can be made about parentage based on blood typing?

If the frequency of the p allele is .63 in the population then what is the frequency of the q allele?

Which description provides the best objective summary of the article in the passage?