In domestic chicken, feather colour and shape are two traits which are controlled by autosomal alleles that are co-dominant. Table 2 shows the alleles and phenotype of both traits. The heterozygous state for feather colour is grey while the heterozygous state for feather shape is mildly frizzled. TABLE 2 Trait Allele Effect Feather colour CB Produces black feathers in homozygotes CW Produces white feathers in homozygotes Feather shape SS Produces straight feathers in homozygotes SF Produces frizzled feathers in homozygotes (a)A farmer bred a black frizzled rooster with a grey mildly frizzled hen. Draw a genetic diagram to show the expected results of this cross. Include in your answer the phenotypic ratios. (b)Is it necessary to do a test cross to determine the genotypes of the offspring? Explain your answer. (c)The farmer would like all his chickens grey and mildly frizzled. What would you advise him to do?Explain your answer.
In domestic chicken, feather colour and shape are two traits which are controlled by autosomal alleles that are co-dominant. Table 2 shows the alleles and
TABLE 2
|
Trait |
Allele |
Effect |
|
Feather colour |
CB |
Produces black feathers in homozygotes |
|
CW |
Produces white feathers in homozygotes |
|
|
Feather shape |
SS |
Produces straight feathers in homozygotes |
|
SF |
Produces frizzled feathers in homozygotes |
(a)A farmer bred a black frizzled rooster with a grey mildly frizzled hen. Draw a genetic diagram to show the expected results of this cross. Include in your answer the phenotypic ratios.
(b)Is it necessary to do a test cross to determine the genotypes of the offspring? Explain your answer. (c)The farmer would like all his chickens grey and mildly frizzled. What would you advise him to do?Explain your answer.
Step by step
Solved in 2 steps
