Question

sometimes, alleles show ________, in which a heterozygous phenotype is somewhere between the two homozygous phenotypes
incomplete dominance
polygenic traits
codominance
sex - linked genes
question 8
10 pts
black (b) is co - dominant to white (w). what percentage of the offspring will be black - and - white if a black cat is crossed with a white cat?
0%
25%
75%
100%

Explanation:

First Question (Fill - in - the - blank with options)

• Incomplete dominance: In incomplete dominance, the heterozygous phenotype is intermediate (between) the two homozygous phenotypes. For example, in snapdragons, a red - flowered plant (homozygous RR) and a white - flowered plant (homozygous rr) produce pink - flowered (heterozygous Rr) offspring.
• Polygenic traits: These are traits controlled by multiple genes, like human height or skin color. They do not fit the description of a heterozygous phenotype being between two homozygous phenotypes for a single - gene trait.
• Codominance: In codominance, both alleles are expressed in the heterozygote, and the phenotype is not intermediate. For example, in blood type AB, both A and B alleles are expressed.
• Sex - linked genes: These are genes located on the sex chromosomes (X or Y), and their inheritance is related to the sex of the individual. They do not relate to the description of a heterozygous phenotype being between two homozygous phenotypes.

Step1: Determine the genotypes of the parents

A black cat with a codominant black allele (B) will have the genotype BB (since black is codominant to white, and to be black, it has two B alleles). A white cat will have the genotype WW (two W alleles).

Step2: Determine the possible gametes

The black cat (BB) can only produce gametes with the B allele. The white cat (WW) can only produce gametes with the W allele.

Step3: Determine the genotype of the offspring

When we cross BB (black cat) with WW (white cat), all the offspring will have the genotype BW.

Step4: Determine the phenotype and calculate the percentage

Since B and W are codominant, the phenotype of BW is black - and - white. Since all (100%) of the offspring have the genotype BW, the percentage of offspring that are black - and - white is 100%.

Answer:

A. incomplete dominance

Second Question (Percentage of offspring)