1
$\begingroup$

enter image description here

Can someone please help with this question? I'm not so sure whether part A should be 11 inches or something else. Also, is part B correct

$\endgroup$
2
$\begingroup$

Question a

  • The only possible genotype that brings a phenotype of 12 inches is: $AABBCC$. Similarly the only possible genotype that bring a phenotype of 6 inches is: $aabbcc$. In consequence the offsprings can only be: $AaBbCc$ which measure $2+1+2+1+2+1 = 9$ inches.

Question b

  • Now the question is: if we breed two $AaBbCc$ how many offsprings measure 11 inches? Because there are three bi-allelic genotypes you have $2^3=8$ possible gametes and therefore you have to draw a 8x8 punnett square. Doing so, just count the proportion of offsprings that measure 11 inches. You can reason slightly more logically and get a faster answer. To measure 11 inches you need to have only capital letters in your genome except at one position. In consequence, if your father gives the gamete $ABC$, you mother should give the gamete $ABc$, $AbC$ or $aBC$. You can inverse the role of the father and the mother and it works as well. Therefore, you have 6 possible combinations that give rise to an offspring that measure 11 inches. Because there are $8 \cdot 8 = 64$ possible combinations, the proportion of offspring that are 11 inch-long is $\frac{6}{64} = \frac{3}{32} = 0.09375 ≈ 0.1$. About 10% of your F2 individuals are 11 inch long.
| improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.