Question

Choose the correct frequency for the following statements.

Statement
                       A sample of a mouse population has a frequency of 0.18 for the dominant allele for black hair coat (B).

                       A sample of a mouse population has a frequency of 0.32 for heterozygote coat colour individuals (Bb).

                       A sample of a mouse population has a frequency of 0.48 for white coat colour individuals.

Frequency
A. Allele frequency

B. Genotype frequency

C. Phenotype frequency

Answer 1

Allele is a form of a gene. We receive one allele from each parent. So they are different forms of the same gene ,present at the same locus. An allele can be dominant or recessive. The first statement " A sample of a mouse population has a frequency of 0.18 for the dominant allele for black hair coat (B)." talks about the frequency of just one allele and is thus referring to allele frequency.

Genotype of an individual indicates the set of alleles that an individual has inherited from ones parents. Genotype can be homozygous doinant (BB), homozygous recessive (bb) or heterozygous (Bb). Here in the second statement, only the frequency of heterozygous individuals is being talked about, i.e these individuals have recieved the dominant allele B from one parent and recessive allele b from another parent so their genotype is Bb and the frequency or number of individuals with the genotype, Bb has been indicated here , so it is genotype frequency . The genotype frequency of heterozygotes is given as 0.32.

Phenotype is the trait that is expressed by individuals that have a particular genotype. It is the character that we observe, which is controlled by the genotype and its interaction with the environment. Here, white coat colour is the phenotype for a specific genotype in the mouse and since the frequency of observable trait , white coat colour is given, the statement "A sample of a mouse population has a frequency of 0.48 for white coat colour individuals." indicates phenotypic frequency.