When gregor mendel crossed a tall plant with a short plant, the f1 plants inherited.
a. one allele from each parent
b. two alleles from each parent
c. three alleles from each parent
d. four alleles from each parent

a. one allele from each parent

An allele in biological sciences is one of the possible forms of a gene that it can inherit. Most genes have two alleles, a dominant allele and a recessive allele. When Gregor Mendel crossed a tall plant with a short plant, the F1 plants inherited an allele for tallness from the tall parent and an allele for shortness from the short parent.

a. one allele from each parent

Explanation:

According to the law of inheritance given by Mendel when two parents are crossed then each of them contributes one allele each for a given gene to make up the offspring.

Therefore, when a tall plant was crossed with a short plant then the cross was as follows:

TT X tt > Tt

Here the offspring had one allele T and other allele t , thus it got one allele from each of its parent.

"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."