Question 1

Which phrase best describes chromosomal nondisjunction?

Accepted Answer

A)  failure of homologous pairs or sister chromatids to separate during meiosis 
B)  failure of sister chromatids to pair during mitosis 
C)  improper pairing of nonhomologous chromosomes during meiosis 
D)  failure of homologous pairs to separate during meiosis

Question 2

What typically leads to cancers associated with mammalian insulin growth factor 2 (Igf2)?

Accepted Answer

A)  duplication 
B)  translocation 
C)  X-inactivation 
D)  loss of imprinting

Question 3

Which of the following most likely describes an individual who is a "carrier" of a genetically inherited disease?

Accepted Answer

A)  The individual has the disease, and any offspring will have the disease. 
B)  The individual does not have the disease, but must have a parent with the disease. 
C)  The individual does not have the disease, but may have offspring with the disease. 
D)  The individual has the disease, and must have a parent with the disease.

Question 4

Consider the following genetic study involving two autosomal genes. One of these, eye colour, has the dominant allele (R) for red eye colour and the recessive allele (r) for yellow eye colour. The other has the dominant allele (T) leading to paws with thumbs, while the recessive allele (t) codes for paws without thumbs. Presuming no linkage between the genes, what should be the phenotype ratio of the offspring produced by a testcross (RrTt × rrtt)?

Accepted Answer

A)  1 red-eyed with thumbs : 1 yellow-eyed without thumbs 
B)  1 red-eyed with thumbs : 1 yellow-eyed with thumbs : 1 red-eyed without thumbs : 1 yellow-eyed without thumbs 
C)  3 red-eyed with thumbs : 1 yellow-eyed without thumbs 
D)  9 red-eyed with thumbs : 3 yellow-eyed with thumbs : 3 red-eyed without thumbs : 1 yellow-eyed without thumbs

Question 5

Suppose that you examine a vial of 100 flies that are all offspring from a single genetic cross, and you find only red-eyed females and red-eyed males present. You allow these flies to interbreed, and in the next generation you find all the females are red-eyed, but you find both red-eyed and white-eyed males. The allele for red eye colour (Xw+) is dominant over the allele for white eye colour (Xw). Which of the following best describes the genotypes of the original parents?

Accepted Answer

A)  Xw+Xw+; XwY 
B)  Xw+Xw; Xw+Y 
C)  Xw+Xw; XwY 
D)  XwXw; Xw+Y

Question 6

A mutation in the human gene for a fibroblast growth factor receptor (FGFR) is related to cartilage formation. Which disorder does this mutation appear to be responsible for?

Accepted Answer

A)  phenylketonuria 
B)  sickle cell anemia 
C)  achondroplasia 
D)  Duchenne muscular dystrophy

Question 7

Figure 10-2 
-In Figure 10-2, what type of change in the chromosomes is depicted?

Accepted Answer

A)  a reciprocal translocation 
B)  a duplication 
C)  an inversion 
D)  a deletion

Question 8

Suppose that you are a genetic counsellor, and a couple comes to you with concerns that if they have a child together, it could have hemophilia. Suppose also that neither one of them has hemophilia, but the woman's biological father did have an X-linked recessive form of hemophilia. Which of the following is the best advice you could give them?

Accepted Answer

A)  Each of their male offspring will have hemophilia, and each of their female offspring will have a 50% chance of having hemophilia. 
B)  None of their offspring should have hemophilia, but each of their female offspring will be carriers for hemophilia. 
C)  Each child that they produce will have a 50% chance of having hemophilia. 
D)  Each of their male offspring will have a 50% chance of having hemophilia, and while their female offspring should not have hemophilia, they will each have a 50% chance of being carriers.

Question 9

Which process is generally the cause for the production of recombinant offspring for two genes on the same chromosome?

Accepted Answer

A)  movement of transposable elements 
B)  exon shuffling 
C)  gene duplication 
D)  crossing-over between homologous chromosomes

Question 10

About 10% to 15% of African Americans are carriers of an autosomal recessive genetic disorder in which a defective version of hemoglobin is produced. What is the name of this disorder?

Accepted Answer

A)  phenylketonuria 
B)  Duchenne muscular dystrophy 
C)  sickle cell anemia 
D)  achondroplasia

Question 11

Suppose that in Drosophila melanogaster, the allele for red eyes is dominant over the allele for purple eyes, and the allele for a grey body is dominant over the allele for a black body. Also suppose that a testcross was done to check for genetic linkage between the genes for these traits, with the following results for the offspring: 478 flies with red eyes and a black body
27 flies with red eyes and a grey body
462 flies with purple eyes and a grey body
33 flies with purple eyes and a black body
Which of the following best represents the map distance between the genes for these two traits?

Accepted Answer

A)  50.0 map units 
B)  30.0 map units 
C)  27.0 map units 
D)  6.0 map units

Question 12

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
-cystic fibrosis

Accepted Answer

A) autosomal recessive 
B) autosomal dominant 
C) X-linked recessive 
D) aneuploidy 
E) genomic imprinting

Question 13

Suppose that a woman with normal blood clotting mates with a man who has X-linked hemophilia. Given that the woman is heterozygous for the trait, which statement best predicts the outcomes of their mating?

Accepted Answer

A)  All the children will have hemophilia. 
B)  Half the boys and none of the girls will have hemophilia. 
C)  Half the boys and half the girls will have hemophilia. 
D)  None of the children should have hemophilia.

Exam 10: Genetic Linkage, Sex-Linkage, and Other Non-Mendelian Inheritance Mechanisms

Which phrase best describes chromosomal nondisjunction?

What typically leads to cancers associated with mammalian insulin growth factor 2 (Igf2) ?

Which of the following most likely describes an individual who is a "carrier" of a genetically inherited disease?

A mutation in the human gene for a fibroblast growth factor receptor (FGFR) is related to cartilage formation. Which disorder does this mutation appear to be responsible for?

Figure 10-2 -In Figure 10-2, what type of change in the chromosomes is depicted?

Which process is generally the cause for the production of recombinant offspring for two genes on the same chromosome?

About 10% to 15% of African Americans are carriers of an autosomal recessive genetic disorder in which a defective version of hemoglobin is produced. What is the name of this disorder?

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all. -cystic fibrosis

Suppose that a woman with normal blood clotting mates with a man who has X-linked hemophilia. Given that the woman is heterozygous for the trait, which statement best predicts the outcomes of their mating?