B! dont worry im positive
Answer:
<h2>(14+16)/1000 *100= 3</h2>
Explanation:
Parental combinations are always more common then other recombinant progenies.
A female fly is heterozygous for three X-linked genes crossed with an abc/Y male. . If single crossover occurs between a & b and between b & c, then the double cross is that, which occurs in both.
Double cross over progeny are always least in number, so here double cross occurs are in abC 14 and ABc 16.
So we are expecting that number of double cross over progeny= (14+16)/1000 *100= 3
The value of the unknown number is 10.5.
Let the unknown number = x
When 20 is subtracted from the number and the result is squared which is equal to the square of the unknown number minus 20:
(x - 20)² = x² - 20
<em>expand the equation;</em>
x² - 40x + 400 = x² - 20
<em>collect similar terms together;</em>
x² - x² - 40x = -20 - 400
-40x = -420

Thus, the value of the unknown number is 10.5.
Learn more about word problem here: brainly.com/question/18336356
The effect of geographic isolation is that the two populations are subjected to different selection (pressures) and geographic conditions. The conditions in the two areas, if different, will produce different alleles in that species and will be selected for, where genetic differences will gradually accumulate between the two different populations.
In time, enough genetic differences will occur so that the two populations will no longer interbreed. Then, by definition, they have become different species.