Question

13. In squash, the fruit can be white, green, or yellow. One gene determines whether the fruit will be white or colored, while another gene determines whether a colored fruit will be yellow or green. Recall that yellow (Y) is dominant over green (y), and white (W) is dominant over color (w). If a squash has yellow fruit, could it have had a white parent? Could it have had a green parent?

Start by writing the possible genotypes for a squash with yellow fruit.

Answer 1

Try to solve it in a reverse manner which will be much more easier for you.

So the possible genotypes for a squash with yellow fruits are wwYy and wwYY.

First checking the probability for wwYy :--

To get the genotype wwYy it must have had crossed with gametes wY & wy. Now checking the probability of wwYy having a White paren t:--

So the parent fruits which can produce these two gametes (wY & wy) can be WwYy (for gamete wY) crossed with wwyy (for gamete wy). And as we can see here that WwYy is the white squash and wwyy is the green squash.

Hence proved that the yellow squash can have had both the white parent as well as the green parent.

(We can also check it by taking the yellow fruit as wwYY (as mentioned above) in a similar way).