Cross a tall red flowering pea plant with short white and get 49 tall red, 51 tall white, 50 short red 50 shor

Cross a tall red flowering pea plant with short white and get 49 tall red, 51 tall white, 50 short red 50 short white. what is the

(A) genotype of the tall red flowering plants (parent)

(B) genotype of short white flowering plants (parent)

(C) genotype of short white flowering plants (offspring)

(D) probability of TtRr offspring

(E) hypothesize an explanation for offspring data

Cross a tall red flowering pea plant with short white and get 49 tall red, 51 tall white, 50 short red 50 shor
The way to look at this problem is the ratios. I'm assuming you've been working with Punnet squares to figure out the probability of the offspring's phenotype and genotype. So you should know by now that if you cross a dominant homozygous trait (both letters capital like RR) with a recessive homozygous trait (both small letters like rr) you get a 1:2:1 genotypic ratio and a 3:1 phenotypic ratio (3 red and 1 white in the case of R being red and r baing white). Clearly that's not what's happening in your question, because your ratio is about 50/50.



You know the recessive characteristic has to be homozygous (rr or tt - t is short, T is tall). The only way you can cross rr with something "red" and get a 50/50 is for the red to have Rr alleles (genes that code for that trait). If it was RR, you could only get Rr in the offspring and they'd all be red. If you cross an rr with an Rr you get 1/2 red and 1/2 white. The same is true for the tall and short alleles.



Start with (B) - it's got both recessive characteristics, so it would be "ttrr".



So, by the explanation above, the answer to (A) would have to be TtRr.



For (C), it's still got only recessive characteristics, so the only way to have this is with the genotype......



For (D) - Is there any way to get a homozygous genotype (RR or TT) if one parent can only contribute the recessive gene? Here it would help you to do a Punnett square. One parent can contribute only "tr" or "tr". The other can contribute "TR", "Tr", "tR", or "tr" When you combine the possible combinations from each parent, what is the probability (HINT, there are 8 possible combos, so your answer can be # in 8, or reduced to # in 4).



(E). I've given you this answer in the explanation of how to do the problem.