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Multiple Choice
A red bull is crossed with a white cow and all of the offspring are roan, an intermediate color that is caused by the presence of both red and white hairs. This is an example of genes that are __________.
A
nonhomologous
B
epistatic
C
polygenic
D
completely dominant
E
codominant
Verified step by step guidance
1
Understand the concept of codominance: Codominance occurs when two different alleles for a gene are both expressed equally in the phenotype of heterozygous individuals. This means neither allele is dominant or recessive, and both contribute to the organism's traits.
Identify the phenotypes involved: In this problem, the red bull and white cow produce offspring that are roan, which is a mix of red and white hairs. This indicates that both the red and white alleles are expressed equally in the offspring.
Recognize the genetic pattern: Since the offspring display traits from both parents equally, this is a classic example of codominance, where both alleles are visible in the phenotype.
Differentiate from other genetic terms: Nonhomologous refers to chromosomes that do not pair during meiosis, epistatic involves one gene affecting the expression of another, polygenic refers to traits controlled by multiple genes, and complete dominance involves one allele completely masking the other.
Conclude with the correct term: Given the information and understanding of codominance, the genes in this scenario are codominant, as both red and white traits are equally expressed in the roan offspring.