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.

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

• Karyotype

• Phenotype

• Environment

• Phenotype

A couple is trying to determine the likelihood of their offspring inheriting hemophilia. The mother is a carrier for the disorder and the father has the disorder. What chance will their offspring have of being a hemophiliac

• 0%

• 25%

• 50%

• 100%

Which of these genotypes would a child that has a recessive disorder have?

• SS

• Ss

• ss

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

• a Y chromosome

• two dominant alleles

• two recessive alleles

• two inactive alleles

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

• polygenic trait

• sex-linked trait

• codominant trait

• autosomal 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?

• White

• Entirely Gray

• Mostly Black

• Black and White

Thomas Morgan’s research with fruit flies determined that

• alleles always assort independently.

• chromosomes are inherited as a group.

• genes never assort independently.

• traits sometimes are inherited as a group.

Two genes cross over 6% of the time. This percentage means that the genes are

• inactivated in 6 out of 100 offspring.

• incompletely dominant in 6 out of 100 offspring

• not inherited together in 6 out of 100 offspring.

• on sex chromosomes in 6 out of 100 offspring.

A female is born with attached earlobes, which is a recessive phenotype. Which of the following genotypes could her parents have?

• RR and RR

• Rr and RR

• Rr and rr

• RR and rr