Exam 9: Patterns of Inheritance

Widow's peak, a pointed hairline on the forehead, is a genetic trait caused by a dominant allele. It can be traced back through a family's history using pedigree analysis. The pedigree shown here is of three generations of a family. Notice that some individuals (shown in gray)have a widow's peak (W = dominant allele and w = recessive allele). -Janice's genotype is ________.

In humans, the presence or absence of dimples is a trait controlled by a single gene. What is the genotype of an individual who is heterozygous for dimples?

Which trait is polygenic in humans?

An individual with the genotype AaBb produces four different gametes in equal proportions. This is a demonstration of ________.

-Recombinant offspring were produced by the mating shown in the accompanying art. What is the recombination frequency of purple-round and red-long offspring?

Which technique is used to collect fetal cells during pregnancy for genetic testing?

Mendel crossed purebred purple-flowered plants with purebred white-flowered plants, and all of the resulting offspring produced purple flowers. The offspring are all ________, and the allele for purple flowers is ________.

Attached earlobes are recessive to free earlobes. What genotypic ratio is expected when an individual with attached earlobes mates with an individual heterozygous for free earlobes?

Which cross will produce only heterozygous offspring?

Round seeds (R)are dominant to wrinkled seeds (r), and yellow seeds (Y)are dominant to green seeds (y). What is the expected phenotypic ratio of a cross between an RrYy and an rryy individual?

An individual with (naturally)curly hair and an individual with (naturally)straight hair mate; all of their offspring have (naturally)wavy hair. If an individual with wavy hair mates with an individual with straight hair, what is the probability that their child will have curly hair?

Achondroplasia is a form of dwarfism caused by a dominant allele. The homozygous dominant genotype causes death, so individuals who have this condition are all heterozygotes. If a person with achondroplasia mates with a person who does not have achondroplasia, what percentage of their children would be expected to have achondroplasia?

What is the key to the recognition of incomplete dominance?

Genes that violate Mendel's principle of independent assortment are ________.

Marfan syndrome is the result of inheriting a single allele. Individuals with Marfan syndrome are tall and long-limbed, and have both cardiovascular and eye defects. Marfan syndrome is an example of ________.

This hypothetical pedigree for a disease in humans illustrates inheritance that is ________.

The parents of a child with unusual disease symptoms take the child to a doctor for help. The doctor suspects that the condition might have a genetic basis. She recommends that the child be taken to a specialty clinic where physicians and staff members are trained to diagnose genetic diseases and counsel parents. Ultimately, the child is diagnosed with a rare recessively inherited disease. The parents are tested for the gene, and both are found to be heterozygous. The parents are expecting another child and ask about a test to determine if this child may carry the disease. All but one of these tests may detect genetic disorders in the unborn child. Choose the EXCEPTION.

Humans have been applying the principles of genetics for many years without actually knowing about genes. Evidence for this is that humans ________.

A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring. What is the recombination frequency of the two gene pairs?

A mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant would be called a ________.