For which of the following are newborn infants not routinely screened at birth?

A) PKU

B) color blindness

C) imperforate anus

D) congenital hip dysplasia

Answer: B) color blindness

Gene mutations in the sex chromosomes of the human would tend to become visibly expressed ________.

A) more frequently in males

B) more frequently in females

C) equally frequently in both sexes

D) in neither males or females

Answer: A) more frequently in males

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

A) AB only

B) A or B only

C) A, B, AB, or O

D) AB or O only

Answer: C) A, B, AB, or O

Amy's hand was exposed to X rays. A gene in a skin cell of her hand mutated. This mutant gene will ________.

A) definitely cause skin cancer

B) replicate itself and be passed on to Amy's children

C) not form an exact duplicate of itself when the cell divides

D) replicate itself when the cell divides but will not be passed on to Amy's offspring

Answer: D) replicate itself when the cell divides but will not be passed on to Amy's offspring

The main way a recessive allele would be expressed even when only one copy is present would be ________.

A) dominance

B) recessive inheritance

C) sex-linked inheritance

D) incomplete dominance

Answer: C) sex-linked inheritance

_______ is the most common type of fetal testing.

A) Blood chemistry

B) Amniocentesis

C) A DNA probe

D) CVS

Answer: B) Amniocentesis

Huntington's disease involves ________.

A) hypersecretion of growth hormone

B) the presence of an extra chromosome

C) degeneration of the basal nuclei of the brain

D) hyposecretion of thyroxine

Answer: C) degeneration of the basal nuclei of the brain

Which of the following statements is true concerning genetic screening?

A) Screening is illegal in over half of the world.

B) Screening can be done only in the first trimester of pregnancy.

C) Genetic screening is rarely done because it yields very little accurate information.

D) Screening can be done before conception by carrier recognition or during fetal testing.

Answer: D) Screening can be done before conception by carrier recognition or during fetal testing.

A chromosomal aberration in which part of a chromosome is lost is known as ________.

A) deletion

B) inversion

C) translocation

D) crossing-over

Answer: A) deletion

Inheritance of stature (height) in humans is probably due to ________.

A) polyploidy

B) polymorphism

C) incomplete dominance

D) polygene inheritance

Answer: D) polygene inheritance

An individual who is heterozygous for a particular trait, yet expresses both alleles of that trait, is an example of ________.

A) dominance

B) recessive inheritance

C) incomplete dominance

D) sex-linked inheritance

Answer: C) incomplete dominance

Which of the following is true concerning environmental influence on genetic expression?

A) It is impossible to alter in any way the expression of a gene in humans.

B) The only time a gene can be influenced by environmental factors is in the second trimester of pregnancy.

C) Environmental factors determine the way in which 90 percent of our genes are expressed.

D) Drugs and nutrition can alter normal gene expression.

Answer: D) Drugs and nutrition can alter normal gene expression.

Sex chromosomes of a normal male are ________.

A) XX

B) YY

C) XY

D) any of these, depending on the father

Answer: C

A woman has blond hair and brown eyes. This statement is best described as indicating ________.

A) allelic pairs

B) recessive traits

C) phenotype

D) genotype

Answer: C) Phenotype

In meiosis the spermatozoa that are produced are genetically unlike each other and unlike the cell that produces them. This is one reason for the great variation among humans. What causes this effect?

A) crossing-over, chromosome segregation, and independent assortment

B) crossing-over and chromosome segregation only

C) chromosome segregation and independent assortment only

D) crossing-over and independent assortment only

Answer: D) crossing-over and independent assortment only

The reason recessive genetic disorders are more frequent than disorders inherited as dominant is that ________.

A) dominant genetic disorders are never expressed in males

B) people carrying dominant genetic disorders always die before birth

C) carriers are not eliminated by the disease before passing the defective alleles on to their offspring

D) recessive genetic disorders are limited to persons of the same ethnicity

Answer: C) carriers are not eliminated by the disease before passing the defective alleles on to their offspring

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

A) incomplete dominance

B) a dominant genetic disorder

C) a sex-linked genetic disorder

D) a recessive genetic disorder

Answer: A) incomplete dominance

An example of multiple-allele inheritance is ________.

A) the ABO blood group

B) the appearance of freckles on the skin

C) the appearance of birthmarks on the skin

D) hair that seems to have several shades of a color

Answer: A) the ABO blood group

Recessive genes are usually expressed in humans only when ________.

A) they are coding for skin color

B) they are coding for genetic diseases

C) the organism is in the embryonic stage

D) both alleles are exactly the same, or homozygous

Answer: D) both alleles are exactly the same, or homozygous

Those characteristics that can be determined on superficial inspection of an individual are known as ________.

A) genotypic

B) polygenic

C) polyspermic

D) phenotypic

Answer: D) phenotypic