Question

Creeper in chickens is a condition where chickens are born with very short legs. The creeper allele (C) is dominant over the normal allele (c). Embryos which are homozygous dominant fail to develop in to viable chickens and die before they hatch. What phenotypic ratio would you expect in the live offspring of a cross between two creeper chickens?

Answer 1

Answer:2 creeper, I normal

Explanation: According to mendelian law when 2 creeper are crossed we should have 3 creeper and 1 normal but because homozgous allele is lethal(lethal means allele that are deleterious and it causes the death of the individual carrying it) it leads it death and we have 2 creeper and 2 normal. The creeper are heterozyous having two different allele.

For everywhere that homozygous individual that are dominant for creeper occur it will always leads to there death because the allele are lethal

Answer 2

Gene interaction

Explanation:

If the homozygous dominant creepers fail to survive then it is obvious that the two creeper chickens who were crossed are heterozygous.

Genotypes of creeper parents: Cc

Types of gametes produced by them:

• Gametes with C allele.
• Gametes with c allele.

When the cross between these chickens will be done then offsprings with three types of genotype will be produced- CC, Cc and cc

Genotypic ratio: CC:Cc:cc = 1:2:1.

Phenotype for CC= creeper but dead

                         Cc= creeper

                         cc= normal

Therefore, the phenotypic ratio=  creeper : normal

                                                    = 2:1