# Simple Mendelian Genetics Question

here is my question:

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?

My Solution:

Let T be the allele for the tall phenotype and t be the allele for the short phenotype.

Then the parental cross would be Tt x TT = 100% tall phenotype (1/2 Tt, 1/2 TT).

Hence the probability of having short offspring should be $\fbox{0}$.

However, the answer key for this question says the answer is $\fbox{$\frac{1}{2}$}$. How can this be??? It really bothers me when the answer key is potentially incorrect because it makes me very unsure, and I end up wasting time trying to figure out if the key is wrong or if I am. Can somebody please let me know if what I did was correct/incorrect??

Thanks

• What's the source? I'd suggest it is an incorrect answer key... or does the question say anything about dominance (if t is dominant to T then the answer would be 1/2). Edit: re-reading your question T is dominant to t thus the answer should be 0. Dec 1, 2014 at 11:15
• Agree with @GriffinEvo. If you have restated the question accurately, the given answer must be wrong. Dec 1, 2014 at 11:32