You perform a test cross of the dihybrid aabb and score the phenotypes of 1000 progeny. assuming independent assortment, how many of the progeny do you expect to display the dominant phenotype for both the a and b genes?

- 750
- 100
- 250
- 500
- 200

250.

Explanation:

A test cross would cross the genotype AaBb with homozygous recessive genotype aabb. The cross between AaBB x aabb would produce progeny in 1:1:1:1 ratio. So, the proportion of the progeny expressing both dominant traits (AaBb) is 1/4.

Therefore, out of the total 1000 offspring, 1/4 x 1000= 250 would express the dominant phenotype for both A and B genes.

a time line cause it goes from 685 to 978

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.