Exam 29: Heredity

This is a first pregnancy for a 22- year- old woman. She is in her 16th week of pregnancy. She is scheduled for an amniocentesis and expresses concern that the "baby will be stuck with the needle." What should the nurse say to the woman?

In humans, farsightedness is inherited by possession of a dominant gene. If a man who is homozygous for normal vision (aa) marries a woman who is heterozygous for farsightedness, what proportion of their children would be expected to be farsighted?

Is genetic diversity due entirely to inherited genes on the sex chromosomes?

Two tall red pea plants, when crossed, produced some offspring that were white and dwarf. Assuming that tallness and redness are dominant, what are the genotypes of the parents?

Jane and Allen have just discovered that their son is a hemophiliac. Neither of them has hemophilia, and Allen claims that no such condition was ever expressed in his family. Jane was told that her father was a hemophiliac and that problems resulting from this condition caused his death. Allen has also been told that hemophilia can only be passed on to an offspring by parents and not by grandparents; he believes that Jane was unfaithful and that the child is not his. If you were a genetic counselor, what would you tell Allen?

A couple whose blood types are A (IAi) and B (IBi) may have a child with which of the following blood types?

Down syndrome is an example of nondisjunction of chromosomes.

Figure 29.2 Use Figure 29.2 to answer the following: -Describe briefly the three mechanisms that lead to genetic variability.

The gene responsible for the condition known as sickle- cell anemia demonstrates _.

Recessive genes are usually expressed in humans only when .

When two genes are on the same chromosome, they are considered linked.

Define phenocopy.

The same allele can have a different effect depending on which parent it comes from.

Among members of the Fuzzy Wuzzy tribe, we will consider two pairs of genes: F = fuzzy hair vs. f = straight hair, and T = long hair vs. t = short hair. A homozygous, straight- shorthaired male marries a homozygous, fuzzy- longhaired female (P1 generation). Their offspring (the F1 generation) intermarry and produce progeny (second generation) of four types: fuzzy- longhaired, fuzzy- shorthaired, straight- longhaired, and straight- shorthaired. The results follow a standard dihybrid pattern. -The 23rd pair of human chromosomes are called chromosomes.

Figure 29.1 -Which of the following statements is true concerning genetic screening?

Dominant alleles are so called because under most circumstances they _ .

Figure 29.1 -Two alleles expressing exactly the same information for a trait are designated as .

Among members of the Fuzzy Wuzzy tribe, we will consider two pairs of genes: F = fuzzy hair vs. f = straight hair, and T = long hair vs. t = short hair. A homozygous, straight- shorthaired male marries a homozygous, fuzzy- longhaired female (P1 generation). Their offspring (the F1 generation) intermarry and produce progeny (second generation) of four types: fuzzy- longhaired, fuzzy- shorthaired, straight- longhaired, and straight- shorthaired. The results follow a standard dihybrid pattern. -Define karyotype.

Figure 29.2 Use Figure 29.2 to answer the following: -Removing a sample of the fluid surrounding the fetus for the purpose of studying the chromosomes is a procedure called .

Among members of the Fuzzy Wuzzy tribe, we will consider two pairs of genes: F = fuzzy hair vs. f = straight hair, and T = long hair vs. t = short hair. A homozygous, straight- shorthaired male marries a homozygous, fuzzy- longhaired female (P1 generation). Their offspring (the F1 generation) intermarry and produce progeny (second generation) of four types: fuzzy- longhaired, fuzzy- shorthaired, straight- longhaired, and straight- shorthaired. The results follow a standard dihybrid pattern. -What is (are) the genotype(s) of the first- generation offspring?