Multiple Choice
In fundamental genetics, how do the terms genotype and phenotype relate to each other?
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1. Introduction to Genetics
Fundamentals of Genetics
Multiple Choice
In Mendelian genetics, a recessive allele will exhibit its phenotype only when the organism has which genotype at that locus?
A
Heterozygous (e.g., Aa)
B
Homozygous dominant (e.g., AA)
C
Either homozygous dominant or heterozygous (AA or Aa)
D
Homozygous recessive (e.g., aa)
Verified step by step guidance1
Understand that alleles come in pairs, one inherited from each parent, and the combination of these alleles at a specific gene locus is called the genotype.
Recall that a recessive allele only shows its associated phenotype when there is no dominant allele present to mask it.
Identify the possible genotypes for a gene with two alleles: homozygous dominant (e.g., AA), heterozygous (e.g., Aa), and homozygous recessive (e.g., aa).
Recognize that in heterozygous individuals (Aa), the dominant allele (A) masks the effect of the recessive allele (a), so the recessive phenotype is not expressed.
Conclude that the recessive phenotype is expressed only when the organism is homozygous recessive (aa), meaning both alleles are recessive.
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