Chapter 7: Extending Mendelian Genetics

A person who has a disorder caused by a recessive allele is

• considered a carrier of the disorder

• homozygous for the recessive allele

• unable to pass the allele to offspring

• certain to have offspring with the disorder

Someone who is heterozygous for a recessive allele that causes a disorder

• is not a carrier of the disorder

• will not have the disorder

• cannot have offspring with the disorder

• will get the disorder late in life

Gene expression is influenced by many factors. Which fo the following is a factor in gene expression?

• karyotype

• pedigree

• environment

• phenotype

The Punnett square in Figure 7.1 shows a cross between two parents who have the genotype Ss for a genetic disorder caused by a recessive allele. Which of the following will have the genetic disorder?

• Ss parent

• Ss offspring

• SS offspring

• ss offspring

Two parents have the genotype Gg for a genetic disorder caused by a dominant allele. What is the change that any of their children will inherit the disorder?

• 25%

• 50%

• 75%

• 100%

The wide range of eye color indicates that eye color is

• sex-linked

• recessive

• polygenic

• epistatic

For an XX female to express a recessive sex-linked trait, she must have

• a Y chromosome

• an inactivated allele

• two recessive alleles

• two dominant alleles

One parent is homozygous for a recessive allele and one parent is heterozygous for a recessive allele in an autosomal dominant genetic disorder. What is the chance that a child of those two parents will have the disorder?

• 25%

• 50%

• 75%

• 100%

Human height occurs in a continuous range because it is affected by the interaction of several genes, making it a

• autosomal trait

• sex-linked trait

• polygenic trait

• codominant trait

Suppose a mouse is homozygous for alleles that produce black fur and homozygous for alleles of an epistatic gene that prevents fur coloration. What color fur will the mouse have?

• all white

• mostly black

• entirely gray

• black and white