Question 1

If an individual has two alleles at a given locus that are different,the individual is said to be ________ for the gene.

Accepted Answer

The answer of If an individual has two alleles at...

Question 2

Both members of a couple are carriers for a recessive disease allele.If the couple has four children,which of the following statements must be true?

Accepted Answer

A) One of the children has the disease. 
B) Two of the children have the disease. 
C) All of the male children have the disease. 
D) Fifty percent of the children could be carriers of the disease.

Question 3

If DNA testing reveals that you carry a single allele for a particular genetic disorder but you do not currently show symptoms of the disease,is it possible that you will develop the disease later in life? Explain.

Accepted Answer

The answer of If DNA testing reveals that you carry...

Question 4

Match each correct statement to the set of alleles listed below.
-heterozygous for an autosomal gene

Accepted Answer

A) Bb 
B) XaY 
C) XAXa 
D) bb 
E) XAXA
F)BB
G)XAY

Question 5

Because an individual with an XX genotype is a female,is an individual with an XO (no second sex chromosome)a male?

Accepted Answer

A) No,because the X always overrides the Y and makes that embryo female. 
B) No,because the Y chromosome contains the gene that makes an embryo male. 
C) Yes,because if there is only one X,the embryo cannot become female. 
D) Yes,because all embryos start off as males.

Question 6

If the male in generation II was affected,what would the pattern of inheritance most likely be?

Accepted Answer

A) X-linked recessive 
B) X-linked dominant 
C) autosomal recessive 
D) autosomal dominant

Question 7

The genetic disorder followed through the pedigree shown is

Accepted Answer

A) recessive and X-linked. 
B) recessive and autosomal. 
C) dominant and X-linked. 
D) dominant and autosomal.

Question 8

Autosomal dominant diseases are exhibited by anyone who carries at least one dominant allele for that gene.How is it that dominant lethal genes,such as the one that causes Huntington disease,can persist in a population?

Accepted Answer

A) The disease-causing allele can "hide" in the heterozygous condition. 
B) The disease develops only under the influence of other genes. 
C) These diseases usually take effect later in life after people have had children. 
D) The environment plays a large role in determining whether the gene is expressed.

Question 9

If two parents are heterozygous for an autosomal recessive disease,

Accepted Answer

A) they are both considered genetic carriers for the disease. 
B) their children have no chance of inheriting the disease. 
C) their children have a 50 percent chance of inheriting the disease. 
D) all of their children will also be heterozygous.

Question 10

Most inherited human disorders are the result of

Accepted Answer

A) recessive mutations of genes located on autosomes. 
B) dominant mutations of genes located on the X chromosome. 
C) recessive mutations of genes located on the Y chromosome. 
D) simultaneous mutations of the same gene on homologous chromosomes.

Question 11

One chromosomal abnormality that is usually fatal is

Accepted Answer

A) a mutation in a gene. 
B) an exchange of material between homologous chromosomes. 
C) extra copies of sex chromosomes. 
D) the addition of an extra autosomal chromosome.

Question 12

Which of the following must be true for a woman who is heterozygous for a given gene?

Accepted Answer

A) She must be heterozygous for all genes. 
B) All of her eggs will contain both of the alleles for that gene. 
C) All of her eggs will contain one allele or the other,but not both alleles. 
D) She carries a rare mutation.

Question 13

An allele that appears more frequently in males is most likely

Accepted Answer

A) dominant. 
B) nonhomologous. 
C) autosomal. 
D) sex-linked.

Question 14

On chromosomes within an individual,there are ________ alleles for a given gene found on ________ chromosomes.

Accepted Answer

A) two;homologous 
B) four;maternal 
C) four;paternal 
D) two;Y

Question 15

Explain how two brothers might have different X chromosomes,but they must share identical Y chromosomes.

Accepted Answer

The answer of Explain how two brothers might have different...

Question 16

An individual who carries one copy of a recessive mutated allele and one normal copy is referred to as a genetic ________.

Accepted Answer

The answer of An individual who carries one copy of...

Question 17

Why are X-linked recessive genetic disorders more commonly seen in males?

Accepted Answer

A) For an X-linked disorder to occur,an individual must receive one allele only found on the X chromosome and a second allele found only on the Y chromosome,which females do not have. 
B) Females must receive two copies of the recessive allele to exhibit the disorder,but males need only one copy. 
C) The alleles of sex-linked genes are carried only on the Y chromosome,which females do not have. 
D) Females only have X chromosomes and genes on the X chromosome are not expressed.

Question 18

A karyotype of an individual with mild mental retardation shows three copies of the X chromosome.If this individual decides to have children,how is her chromosomal abnormality likely to affect her offspring?

Accepted Answer

A) All of her children will inherit an extra copy of the X chromosome. 
B) Any female children have a 75 percent chance of inheriting an extra copy of an X chromosome. 
C) She will be unable to produce male children. 
D) Half of her eggs will contain an extra copy of the X chromosome.

Question 19

A ________ is a chart that shows genetic relationships within a family over several generations.

Accepted Answer

A) karyotype 
B) pedigree 
C) Punnett square 
D) single-gene disorder map

Question 20

Match each correct statement to the set of alleles listed below.
-dominant homozygous for an autosomal gene

Accepted Answer