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? Yes Could it have had a green parent? Yes

Could it have a white parent: Yes

Could it have a green parent: Yes

Explanation:

There are many variables to be taken into account when breeding plants to observe genetics.

In a yellow fruit, the genotype has to be Y_ww, this genotype can be seen to have a dominant gene (Y) that codes for yellow, and recessive (ww) to code for color. However if there was a single dominant W gene, then the fruit would be white, regardless of the Y/y gene, hence a white fruit would have the genotype __W_.

Can a yellow fruit come from a white parent?

If we assume the parent had a genotype like YyWw, and that plant formed gametes (YYWW, YYWw, YYww, YyWW, YyWw, Yyww, yyWW, yyWw, yyww), we can see that most of those genotypes will code for the same phenotype (eg. YYWw and yyWW will both code for white fruit), but there will be offspring with yellow fruit (Yyww).

Can a green fruit come from a white parent?

Again, looking at the genotypes shown in the previous example, the genotype coding for green fruit (yyww) is there, however it is very unlikely that self-pollination of a white parent will produce a green offspring (although it is possible).