The appearance of freckles is considered:
a the genome.
b the phenotype.
c the genotype.
d sex linked.

B. the phenotype

In females, one of the X chromosomes is inactivated by:
a environmental factors.
b enzymes coded for by mitochondrial DNA.
c epigenetic markers.
d the number of dominant genes present on each X chromosome

C. epigenetic markers

Males tend to inherit more sex-linked conditions because:
a. they have two Y chromosomes.
b. there is no corresponding alleles on their X chromosomes.
c. they have more chromosomes than females.
d. there is no corresponding allele on their Y chromosomes.
e. they have two X chromosomes.

D. there is no corresponding allele on their Y chromosomes.

A change in the genetic structure of a gene is called:
a mutation.
b deletion.
c duplication.
d translocation.
e inversion.

A. mutation

Extrachromosomal inheritance involves genes passed on by the mother's:
a mitochondria.
b Golgi bodies.
c smooth ER.
d chromosomes.
e cytoplasm.

A. mitochondria

The most common form of fetal testing is:
a somatic visualization.
b chorionic villi sampling.
c teratogenic sampling.
d gene therapy.
e amniocentesis.

E. amniocentesis

The expression of genes is called the:
a genotype.
b autotype.
c phenotype.
d pedigree.
e genome.

C. phenotype

Traits that display continuous phenotypic variation are usually determined by this form of inheritance.
a Dominant-recessive inheritance
b Incomplete dominance
c Sex-linked inheritance
d Polygenic inheritance
e Multiple-allele inheritance

D. polygenic inheritance

What is the probability of having a child with a recessive trait if both parents are heterozygous for the trait?
a 50%
b 25%
c 100%
d 10%
e 75%

b. 25%

Heterozygous individuals that can pass on recessive, abnormal conditions are referred to as:
a zygotic.
b phenotypically challenged.
c deleterious donators.
d carriers.
e recessively compromised.

d. carriers

A type of treatment useful in correcting single-gene disorders is:
a genetic dysplasia.
b somatic recombination.
c gene therapy.
d amniocentesis.
e chorionic villi sampling.

c. gene therapy

Genes that are located on the same chromosome are said to be:
a dominant.
b crossed.
c linked.
d syncopated.
e tied.

C. linked

In the human blood type AB, the alleles are:
a codominant.
b dominant.
c sex-linked.
d polygenic.

a.codominant

Which of the following disorders is NOT inherited as simple recessive traits?
a Cystic fibrosis
b Albinism
c Tay-Sachs disease
d Down syndrome
e Schizophrenia

d. down syndrome

Which of the following is NOT a source of genetic variation?
A) independent assortment of chromosomes
B) crossover of homologs
C) age of either or both parents
D) random fertilization of eggs by sperm

C

True or False

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

T

True or False

Most genetic disorders are inherited through dominant genes.

False

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

incomplete dominance

True or False

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

True

Some segments of the Y chromosome have no counterpart on the X chromosome. T/F

True