Question

some cattle are polled (P) which is dominant to non-polled (p). if a male heterozygous steer breeds with a female non-polled cow, what are their chances of producing polled offspring? **show your work as a Punnett Square** and write the genotypic and phenotypic ratios

Answer 1

A heterozygous male steer (Pp) bred with a non-polled cow (pp) has a 50% chance of producing polled offspring, as determined by a Punnett square showing a 1 Polled:1 Non-polled phenotypic ratio.

Step-by-step explanation:

The question involves a genetic cross involving polled (horns absent) and non-polled cattle. A Punnett square can be used to predict the genotypic and phenotypic ratios of the offspring from such a cross. Let 'P' represent the dominant polled allele and 'p' the recessive non-polled allele.

The heterozygous male steer genotype is Pp, and the non-polled cow's genotype is pp. By listing the potential gametes along the top and side of the Punnett square (P, p from the steer and p, p from the cow), we can predict the genotypes of the offspring. The top of the square would have the steer's gametes (P, p) and the side would have the cow's gametes (p, p).

When filled, the Punnett square looks like this:

• Pp (Polled)
• Pp (Polled)
• pp (Non-polled)
• pp (Non-polled)

From this, we can derive the following ratios:

• Genotypic ratio: 1 Pp:Pp:pp:pp which simplifies to 2 Pp:2 pp
• Phenotypic ratio: 2 Polled:2 Non-polled which simplifies to 1 Polled:1 Non-polled

Therefore, there is a 50% chance of producing polled offspring from this cross.