Ch. 29

Use the following information to solve the problem using a Punnett square. Assume that the dominant "B" allele encodes brown eyes and the recessive "b" allele encodes blue eyes. An individual with the genotype BB has children by mating with an individual of the genotype bb. What is the percent chance that they would have children with blue eyes?

0% All the offspring would have brown eyes.

A couple's first child has cystic fibrosis. The gene for cystic fibrosis is autosomal recessive, and the mode of inheritance is simple dominant/recessive inheritance. Neither parent has the disease. What are the odds that the couple's next child will have the disease?

1 in 4 The scenario indicates that both parents are asymptomatic carriers. If you construct a Punnett diagram, you will find that the odds of any offspring of this coupling has a 1 in 4 chance of inheriting the two recessive genes, leading to the disease.

How many chromosomes are in a haploid human cell?

23 This is the haploid number of human chromosomes.

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

A, B, or AB only

Sam has type A blood. The blood type of his partner is not known. Which of the following blood types are not at all possible among their offspring?

All are possible Depending on whether Sam is heterozygous with a recessive allele to donate or if he donates the A allele, all of the choices listed are possible for Sam's offspring.

If two parents are heterozygous (Tt) for a trait, which of the following is NOT a possibility for their offspring?

All of their offspring would be dominant for the trait.

If two parents are heterozygous (Tt) for a trait, which of the following is NOT a possibility for their offspring? Half of their offspring would be heterozygous. All of their offspring would be dominant for the trait. Most of the offspring would have the dominant phenotype. Half of the potential offspring would be genotypically different than the parents.

All of their offspring would be dominant for the trait. One quarter of their potential offspring would be recessive for the trait.

Which statement is most correct? Alleles are variations of the same gene. If you have two copies of a gene for one trait, you are heterozygous. If you only have one copy of a gene, you are homozygous. If you have two copies of a dominant gene, you are considered heterozygous.

Alleles are variations of the same gene.

________ is the most common type of fetal testing.

Amniocentesis

Because lethal dominant genes are always expressed and result in the death of the embryo, fetus, or child, dominant gene disorders are NOT seen among adults. T/f

False

Y chromosomes contain far more genes than X chromosomes. T/f

False

Steven has the dominant tongue rolling phenotype but he does not know his genotype. His wife has the recessive non-tongue rolling trait. If their son cannot roll his tongue this means ________.

Steven has a heterozygous genotype

Some females have only one X chromosome, and their genotype is expressed as XO. There are living males with the genotype XXY and XYY, but none with genotype YO. What explains this difference?

The X chromosome has genes that encode for proteins that are essential for life, so a conception that resulted in an absent X would not be viable.

Height in humans is determined by polygene inheritance. T/f

True

Hemophilia is an X-linked condition caused by a recessive gene. T/f

True

It is possible for a baby to have type O blood if neither parent is type O. T/f

True

Your phenotype is the physical output of your genotype. T/f

True

How many skin colors would there be if it was inherited in a simple recessive pattern rather than in a polygenetic fashion?

Two In simple recessive inheritance, there are three possible genotypes and two phenotypes.

The genotype of a normal man is ________.

XY

A dominant allele is best defined as ________.

an allele that stops or hides the expression of another allele

The prefix Blank means chorion or choroid.

chori-

A fetal test to examine bits of placenta and perform karyotype analysis is Blank sampling.

chorionic villus

An allele that can mask another allele is said to be __________.

dominant A dominant allele cannot be masked. Its trait will appear regardless of its partner allele on the other matching chromosome.

The prefix Blank means gene or generating offspring.

gen(o)-

The genetic makeup, or DNA sequence, of a person is their Blank

genotype.

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

incomplete dominance

The prefix Blank means nucleus of a cell, nut, or kernel.

karyo-

The 46 chromosomes of a cell displayed in homologous pairs is a Blank.

karyotype.

Genes on the same chromosome are said to be __________.

linked Genes on the same chromosomes are said to be linked.

Nuclear DNA is not the only source of genetic information in the cell. Which of the following is another source of DNA in the cell?

mitochondria Mitochondria have their own DNA separate from the nuclear DNA of the cell. Mitochondrial genes are transmitted to the offspring almost exclusively by the mother because the ovum donates essentially all the cytoplasm in the fertilized egg.

Which of the following is not a source of genetic variation? mitosis of fertilized egg random fertilization of eggs by sperm crossover of homologous chromosomes independent assortment of chromosomes

mitosis of fertilized egg Cell division by mitosis results in two daughter cells that are genetically identical to the parent cell.

The genetic determination of blood type is based on __________ inheritance.

multiple-allele There are 3 alleles for blood type

Which of the following is a noninvasive method for predicting genetic disease?

pedigree Pedigree analysis involves looking at phenotypic data from person's family tree to analyze whether or not an individual might be prone to a genetic anomaly.

The prefix Blank means show, showing or phenol.

pheno-

The expression of a genotype, or the traits shown once proteins are produced, represent the Blank

phenotype.

Skin color, controlled by three separately inherited genes that each exist in two allelic forms (A, a; B, b; C, c), is an example of which form of inheritance?

polygene inheritance

What pattern of inheritance results from the effects of multiple genes at different chromosome locations to produce one overall phenotype?

polygene inheritance

Skin color, controlled by three separately inherited genes that each exist in two allelic forms (A, a; B, b; C, c), is an example of which form of inheritance?

polygene inheritance Polygene inheritance is the term that describes when multiple genes control one overall phenotype.

Which of the following does not match the term to its correct definition/description?

recessive: gene expressed when present Recessive traits are only expressed if a person has two recessive alleles.

Jeff made a detailed pedigree of his extended family over several generations. He noted all of the family members who expressed a specific genetic trait. He noted that this trait was not observed in every generation, and that it was expressed far more frequently in the males of the family. Based on this information alone, what terms would best describe this trait?

sexx-linked recessive

Hereditary characteristics are transmitted to offspring by genes. T/f

true