In mouse, genes X, Y and Z are on chromosome 2. The map of genes X, Y and Z is: XYZ
20 m. u. 30 m. u.
You cross an individual with genotype XXYYZZ to an individual with genotype xxyyzz, and F1 progeny are collected. Assume interference between regions (X-Y and Y-Z) is 100%. When an F1 individual produces gametes, what proportion of its gametes would have xyz genotype?
a. 10%
b. 20%
c. 25%
d. 30%
e. 40%
f. 50%
g. 0%
h. None of these above

In F1 we will get 100% XxYyZz

each of these organism has two chromosomes that look like this

X20Y30Z

x20y30z

Those two chromosomes are homologous

we want a gamete that contains the second chromosome where crossing-over didn't occur. The distance between the genes of the chromosomes in map units is equal to the frequency of recombination in percentage. Therefore there is a 20% that x and y will recombine and a 30% chance that y and z will recombine. We want a chromosome that is not recombined.

The possible gametes are

XYZ XYz XyZ Xyz xYZ xYz xyZ xyz if the genes were on different chromosomes xyz would be 1/8 or 12,5%

Since there is a 20% that the genes x and y will recombine that means there is a 80% chance that they won't and since there is a 30% chance that the genes y and z will recombine that means there is a 70% chance that they won't.

80%*70%=56% chances that the genes won't recombine. But, there are two non-recombinant gametes:XYZ and xyz therefore the chances for xyz is 56/2=28%

the framers of the constitution insisted that federal judges be nominated instead of elected due to their desire to have judges above the shifting whims of the masses.

the hope, whether achieved or not, was that federal judges would only be beholden to the law and that by not having judges be elected, they would be protected if that law dictated an outcome that ran counter to popular opinion.

im not in connections yet but i might can you some questions. what grade are you in?