TEAS 7 Science Practice Test Related

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Which of the following is a true statement about dominance in genetics?

  • A. All genes adhere to Mendel's law of dominance.
  • B. A dominant allele will always be expressed.
  • C. When two dominant alleles are present, the resulting phenotype will express both traits.
  • D. There are three or more alleles possible for all genes.
Correct Answer: B

Rationale: In genetics, dominance refers to the relationship between two different alleles of a gene where one allele (dominant) masks the expression of another allele (recessive) in an individual's phenotype. The correct statement about dominance is that a dominant allele will always be expressed in the phenotype, even in the presence of a recessive allele. This means that if an individual has at least one dominant allele for a particular trait, that trait will be expressed. Choice A is incorrect because not all genes follow Mendel's law of dominance; exceptions do exist. Choice C is incorrect because when two dominant alleles are present, only one will be expressed due to complete dominance. Choice D is incorrect as there can be more than three alleles for a gene, and not all genes have three or more alleles.