Bio 141 Chapter 19

What is the likelihood that a parent with type AB blood would have a child with type O blood?

0 %

"In humans, a widow's peak is a dominant trait,and a straight hairline is a recessive trait." If an individual homozygous dominant for widow's peak has a child with an individual heterozygous for widow's peak, what is the chance that the child will have a widow's peak?

100%

"In humans, the ability to roll the tongue is a dominant trait;the inability to roll the tongue is a recessive trait." If two individuals heterozygous for this trait have a child, what is the chance that the child will not be able to roll his tongue?

25%

Cystic fibrosis is a genetic disorder that results from the inheritance of two recessive alleles. What is the chance that a child will inherit the disorder if one parent is heterozygous for this gene and one parent has cystic fibrosis?

50%

Which of the following statements correctly expresses the relationship between dominant and recessive alleles?

A dominant allele masks the expression of a recessive allele in a heterozygote

In humans, the allele for a widow's peak (W) is dominant and the allele for a straight hairline (w) is recessive. This trait shows complete dominance. Which of the following represents the possible phenotypes in the offspring of two parents, both with a straight hairline?

All offspring will have a straight hairline.

Which of the following statements is/are true?

Both that genotype determines phenotype and that environment can affect phenotype are true.

Examination of a karyotype reveals 23 pairs of chromosomes, with each homologous pair illustrating similar size and centromere location. Which of the following can be concluded from this karyotype?

The individual is a female.

Which one of the following is TRUE regarding an individual who has inherited one sickle-cell gene and one normal gene for hemoglobin?

The individual is more likely to resist malaria than an individual with two normal genes for hemoglobin.

Which of the following would provide an EXCEPTION to Mendel's law of independent assortment?

adjacent genes on the same chromosome

The flower color in this plant is inherited by incomplete dominance. If a red flower that is homozygous dominant is crossed with a white flower that is homozygous recessive, the color of the offspring flowers will be expected to be...

all pink.

What is the significance of crossing-over, independent assortment, and random fertilization?

an increase in the genetic diversity of gametes and zygotes

A recessive phenotype will be expressed when __________.

both alleles present are recessive

In the human ABO blood-typing system, an individual with A and B alleles will express both A and B phenotypes on his or her red blood cells. This is an example of __________.

codominance

Which of the following results in the separation (or unlinking) of linked genes?

crossing-over during meiosis I

In eukaryotic cells DNA has the appearance of a _____.

double helix

A(n) ________ refers to the complete set of DNA within the chromosomes of an individual.

genome

Nondisjunction in meiosis I results in failure of __________.

homologous chromosomes to separate

If both alleles of a particular gene are identical, the person is said to be

homozygous

The law of segregation states that __________.

in the formation of gametes, alleles separate from each other so that each gamete receives only one allele

The offspring resulting from a cross between a nearly white horse (cc) and a chestnut-colored horse (CC) is of an intermediate color (between white and chestnut). Which one of the following patterns of inheritance best explains this?

incomplete dominance

Genes for different traits located on the same chromosome in close proximity are called ________ genes

linked

In polygenic inheritance,

multiple alleles and genes contribute to a phenotype

Place the following in order from smallest, simplest, least complex, to largest and most inclusive:

nucleotide, gene, chromosome, genome

DNA is composed of building blocks called _____.

nucleotides

The inheritance of a trait that is determined by many genes acting together, such as eye color, is called ________ inheritance.

polygenic

When continuous variation occurs in a phenotypic trait, the trait is likely due to __________.

polygenic inheritance

The Punnett square is a useful tool for

predicting the ratios of possible genotypes of a particular combination of alleles

All of the following human traits are determined by the interaction of multiple genes and alleles, EXCEPT __________.

sickle cell anemia

The trend toward increased height and weight due to improved nutrition in certain human populations is an example of the effect of ________ on phenotypes.

the environment