Consider a study of two genes, "a" and "b". each gene has two alleles, represented by upper- and lower-case letters. assume that an upper-case letter represents a dominant allele, and a lower-case letter represents a recessive allele. if the parental cross ("p" generation) is aabb x aabb, which the following crosses would represent an f1 testcross?

AaBb × aabb

Explanation:

A test cross is a cross between an unknown genotype (dominant phenotype) with a homozygous recessive genotype in order to discover the actual genotype of the species exhibiting dominant phenotype.

This is because one allele of a gene is capable of masking the expression of another, the allele masking is called DOMINANT allele while the allele being masked is called RECESSIVE allele. The combination of these two alleles is termed heterozygosity.

An organism that is phenotypically dominant for a specific trait may either be heterozygous or homozygous for that gene. For example, a plant gene for tallness with an dominant allele T, and recessive allele t. This plant will need tall if the genotype is TT (homozygous dominant) or Tt (heterozygous dominant). In order to know which of these genotypes the plant actually has, a test cross is conducted.

In this example, two genes A and B are involved. For the first gene, A represents dominant allele while a represents recessive allele. For the second gene, B represents dominant allele while b represents recessive allele.

In a cross involving parents AABB (homozygous dominant for both genes) and aabb (homozygous recessive for both genes), the F1 progeny will all exhibit phenotypic dominance (AaBb).

However, we cannot know the genotype by merely looking at the phenotype. We cannot ascertain yet whether the dominance is heterozygous or homozygous, hence the need for a test cross.

The test cross is between the dominant F1 progeny and a homozygous recessive i.e. AaBb × aabb. Some of the F2 generation will show recessive traits if the unknown genotype is heterozygous.

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.

b is the answer and if you need further with anything message me