Question 1

Who developed the concept of mapping genes on chromosomes when he was an undergraduate student?

Accepted Answer

A)  Thomas Morgan 
B)  Francis Crick 
C)  James Watson 
D)  Alfred Sturtevant

Question 2

What is the name of the human disorder in which a deletion from chromosome 5 typically leads to severe mental retardation and a malformed larynx?

Accepted Answer

A)  triple-X syndrome 
B)  cri-du-chat 
C)  Down syndrome 
D)  Turner syndrome

Question 3

A woman with which of the following human conditions would exhibit normal physical features?

Accepted Answer

A)  triple-X syndrome 
B)  Turner syndrome 
C)  Down syndrome 
D)  cri-du-chat

Question 4

Suppose that you have discovered a new mutant in Drosophila melanogaster. What kinds of genetic crosses should you do to determine if the allele causing the mutation is inherited as an autosomal dominant trait, an autosomal recessive trait, or a sex-linked trait?

Accepted Answer

The answer of Suppose that you have discovered a new...

Question 5

Suppose that a woman with normal blood clotting mates with a man who also has normal blood clotting, and that their first child is a boy who has X-linked hemophilia. Which statement best predicts the outcomes of their mating?

Accepted Answer

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

Question 6

Which of the following occurs in cells of human individuals with three or more X chromosomes?

Accepted Answer

A)  Two X chromosomes remain active, and all others are inactivated. 
B)  One X chromosome remains active, and the rest are inactivated. 
C)  All of the X chromosomes remain active. 
D)  Two X chromosomes remain active in females and one remains active in males; the rest are inactivated.

Question 7

Suppose that you examine a vial of 100 flies that are all offspring from a single genetic cross. Also suppose that the only females you see present are red-eyed, but the males you see present are both red-eyed and white-eyed. The allele for red eye colour (Xw+) is dominant over the allele for white eye colour (Xw). Which of the following describes the genotypes of the parents?

Accepted Answer

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

Question 8

Under which condition would you expect the SRY gene to be switched on?

Accepted Answer

A)  if no X chromosome is present 
B)  if an X chromosome is present 
C)  if a Y chromosome is present 
D)  if two X chromosomes are present

Question 9

How are mitochondria inherited in most multicellular organisms?

Accepted Answer

A)  only from the father 
B)  from the mother for females and from the father for males 
C)  randomly from either the father or the mother 
D)  only from the mother

Question 10

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.
-hemophilia

Accepted Answer

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

Question 11

Prenatal diagnosis techniques such as amniocentesis and chorionic villus sampling involve the removal of cells that were produced by an embryo. What are these cells then used for?

Accepted Answer

A)  to test for the presence of mutant alleles or chromosomal alterations 
B)  to treat diseases 
C)  for implantation to produce pregnancy 
D)  to develop embryonic stem cells

Question 12

What are the two major types of chromosomes in many eukaryotic organisms?

Accepted Answer

A)  sex and non-sex 
B)  XY and ZZ 
C)  sex and autosomes 
D)  autosomes and ZZ

Question 13

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.
-red-green colour blindness

Accepted Answer

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

Question 14

From which studies did the discovery of sex-linked genes and the production of the first chromosome map arise?

Accepted Answer

A)  from the studies of pea plants 
B)  from the studies of humans 
C)  from the studies of corn 
D)  from the studies of fruit flies

Question 15

Which of these disorders has X-linked recessive inheritance?

Accepted Answer

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

Question 16

Suppose you are a genetic counsellor, and a man and woman come to you with concerns that if they have a child together, it could have hemophilia. Also suppose that the woman has an X-linked recessive form of hemophilia, but the man does NOT. 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)  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. 
C)  None of their offspring should have hemophilia, but each of their female offspring will be carriers for hemophilia. 
D)  Each of their male offspring will have hemophilia; and while their female offspring should not have hemophilia, they will all be carriers.

Question 17

Prader-Willi syndrome and Angelman syndrome are both caused by the same genetic deletion on human chromosome 15, but they have very different phenotypes. Whether one or the other syndrome occurs depends upon which parent provided the chromosome with the deletion. What is this pattern of inheritance an example of?

Accepted Answer

A)  sex-linked inheritance 
B)  cytoplasmic inheritance 
C)  genomic imprinting 
D)  uniparental inheritance

Question 18

Suppose you are a genetic counsellor, and a man and woman come to you with concerns that if they have a child together, it could have hemophilia. Also suppose that the man has an X-linked recessive form of hemophilia, but the woman does NOT, and that genetic tests reveal the woman is NOT a carrier for hemophilia. Which of the following is the best advice you could give them?

Accepted Answer

A)  Each child that they produce 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 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. 
D)  Each of their male offspring will have hemophilia, and each of their female offspring will have a 50% chance of having hemophilia.

Question 19

Suppose you are a genetic counsellor, and a man and woman come to you with concerns that if they have a child together, it could have cystic fibrosis. Also suppose that genetic tests reveal that the woman is a carrier for cystic fibrosis but the man is NOT. Which of the following is the best advice you could give them?

Accepted Answer

A)  Each child that they produce will have a 50% chance of having cystic fibrosis, and the other 50% will be carriers. 
B)  They should not have any concerns, because no child that they produce should have cystic fibrosis. 
C)  No child that they produce should have cystic fibrosis, but each of their children will have a 50% chance of being a carrier. 
D)  Each of their offspring will have cystic fibrosis.

Question 20

Why do carriers for sickle cell anemia have a genetic advantage in some situations over those who are not carriers?

Accepted Answer

A)  because carriers have the ability to carry more oxygen in their blood 
B)  because carriers have increased resistance to malaria 
C)  because carriers have hyperactive immune systems 
D)  because carriers have lower blood pressure

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