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Development of antibiotic resistant strains of pathogenic bacteria such as MRSA is due to evolution of the non-resistant strains to resistant strains.

Alleles that are both expressed in a heterozygote are _____.

_______________ traits are determined by more than one gene, with each gene providing a small, but additive effect.

In familial hypercholesterolemia, individuals homozygous for the allele causing the disorder completely lack receptors on liver cells that take up cholesterol from the blood stream. Heterozygotes have one-half the number of receptors while individuals homozygous for the normal allele are phenotypically normal. This is an example of _____.

Microevolution refers to changes in allele frequencies in populations.

Sickle cell disease and cystic fibrosis are_______________ whereas hypertension ____________________.

Consider a gene in a population where the dominant allele G occurs in 56% of the gametes. What is the frequency of the recessive allele?

In mice, the spinning behavior is caused by a dominant gene that affects the mouse’s equilibrium. This gene is lethal if two alleles are present. Two “spinning mice” are mated together. What are the phenotypes of the offspring and in what proportion?

A man with AB blood is married to a woman with AB blood. What blood types will their children be and in what proportion?

Hunting reduced Northern elepnat seals population size to as few as 20 individuals at the end of the 19th century. Their population has since rebounded to over 30,000—but they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted. This is an example of