In chickens, comb shape is determined by alleles at two loci (r, r and p, p). a walnut comb is produced when at least one dominant allele r is present at one locus and at least one dominant allele p is present at a second locus (genotype r_ a rose comb is produced when at least one dominant allele is present at the first locus and two recessive alleles are present at the second locus (genotype r_ pp). a pea comb is produced when two recessive alleles are present at the first locus and at least one dominant allele is present at the second (genotype rr if two recessive alleles are present at the first and at the second locus (rr pp), a single comb is produced. a walnut is crossed with a pea chicken and the offspring consists of 3/8 walnut, 3/8 pea, 1/8 rose and 1/8 single. what are the probable genotypes of the parents

RpPp x RpPp

Explanation:

For the recessive trait to be expressed, both parents should have at least 1 allele for the recessive trait. Now you can see that both recessive traits were expressed in at least one of the off-springs, this means that both parents had the allele for each recessive trait.

scientists have discovered that hiv does not cause aids by the virus's direct effect on the host's immune cells, but rather through the cells' lethal influence on one another. researchers from the gladstone institutes have revealed that hiv does not cause aids by the virus's

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."