The tiny fruit fly is a superstar of genetics research. Thousands of experiments have explored how flies inherit traits. Wing shape, body color, eye color, and head shape are a few traits under investigation. Fruit flies make good study subjects because they are inexpensive, take little space, and breed quickly. In addition, humans and fruit flies share 75% of their disease genes. By studying fruit-fly genetics, we can learn about human illness. Short-winged fruit flies studied in the lab cannot fly because they have an allele that causes them to grow tiny wings (w). Normal fruit flies, known as “wild-types”, have fully functional wings (W). The wild-type wing is the dominant allele.
If you cross one short-winged fly (ww) with a wild-type fly (WW), what is the probability of getting a short-winged offspring in the F1 generation?
Explain your reasoning.

a. 0

b. There are no short winged genes expressed in this generation

Explanation:

a. What is the probability of getting a short-winged offspring in the F1 generation?

Since we have the ww gene for the short winged fly and the WW gene for the wild type fly.

In the F1 generation, we have

Ww, Ww, Ww and Ww

Since the W wild-type allele is the dominant gene, in the F1 generation, all the fruit flies have wild-type wing.

Probability of short-winged fly, P(short-winged) = number of short-winged genes/total number of genes =

number of short-winged genes = 0

total number of genes = 4  

P(short-winged) = 0/4 = 0

b. Explain your reasoning.

Since the wild winged type allele is the dominant gene, there are no short winged genes expressed in this generation. Thus, the probability of obtaining a short-winged fly in the F1 generation is therefore zero.  

the answer is b. hope this !