Genetics Final Exam: Tailored Questions from
Renowned Educators Worldwide with Detailed
Rationale for Top Grades
An organism whose chromosome number is 2n+1 and has an extra chromosome is:
a. a monosomic
b. a nullisomic
c. a tetrasomic
d. a trisomic - correct answer- -d. tridsomic
An organism whose chromosome number is 2n+2 and has two extra chromosomes is:
a. a monosomic
b. a nullisomic
c. a tetrasomic
d. a trisomic - correct answer- -c. tetrasomic
Which of the following non disjunction events would give rise to an XYY human?
a. primary non disjunction in the father.
b. primary non disjunction in the mother.
c. secondary non disjunction in the father.
d. secondary non disjunction in the mother.
e. this is the normal chromosome compliment for a human, so non disjunction did not
occur. - correct answer- -c. secondary non disjunction in the mother
A patient with Turner's syndrome (45,X) is found to be colorblind. Both her mother and
father have normal vision. Can we tell whether nondisjunction occurred in her mother or
father?
,a. nondisjunction did not occur.
b. there was nondisjunction, but it could have happened in either the mother or father.
c. nondisjunction occurred in father.
d. nondisjunction occurred in mother.
e. not enough information to determine whether nondisjunction took place or not. -
correct answer- -c. non disjunction occured in the fater
Human monosomics all abort before birth, with the exception of Turner's Syndrome (45,
XO). Why would you expect this monosomic to survive when other monosomics do not?
a. the X chromosome is the smallest, therefore this monosomic is missing very little DNA.
b. normal females have only one functioning X chromosome per cell due to the formation
of Barr bodies;
Turner's syndrome mimics that situation.
c. X chromosomes carry large numbers of lethal genes, therefore a person with only one X
chromosome will have less
chance of getting a lethal gene.
d. unlike autosomes, sex chromosomes only carry information for sex determination, so
one chromosome carries all the information that is necessary.
e. Turner's syndrome is actually due to a trisomic condition; no human monosomics are
known. - correct answer- -b. normal females have only one functioning X chromosome per
cell due to the formation of Barr bodies;
Turner's syndrome mimics that situation.
Cri du chat Syndrome in humans is caused by a (an):
a. trisomic condition.
b. deletion.
c. monosomic condition.
d. paracentric inversion.
, e. reciprocal translocation. - correct answer- -b. deletion
Down Syndrome is _________.
a. a trisomy 21
b. the result of non-disjunction in meiosis
c. 2N=2X=46+1
d. all of the above
e. none of the above - correct answer- -d. all of the above
The probability of a couple having a child afflicted with Down syndrome increases in cases
where the:
a. male parent is less than 20 years old.
b. female parent is less than 20 years old.
c. male parent is more than 40 years old.
d. female parent is more than 40 years old.
e. the probability is the same regardless of the age of either parent. - correct answer- -d.
the female parent is more than 40 years old.
Down syndrome in humans is due to a trisomic condition for chromosome 21. Which of the
following is accurate with respect to this genetic disorder?
a. it is observed more frequently when the mother is under 30 years of age.
b. it is observed more frequently when the father is over 30 years of age.
c. it is never observed when the mother is under 30 years of age.
d. it is observed more frequently when the mother is over 45 years of age.
e. it is always observed when the mother is over 45 years of age. - correct answer- -d. it is
observed more frequently when the mother is over 45 years of age.
Renowned Educators Worldwide with Detailed
Rationale for Top Grades
An organism whose chromosome number is 2n+1 and has an extra chromosome is:
a. a monosomic
b. a nullisomic
c. a tetrasomic
d. a trisomic - correct answer- -d. tridsomic
An organism whose chromosome number is 2n+2 and has two extra chromosomes is:
a. a monosomic
b. a nullisomic
c. a tetrasomic
d. a trisomic - correct answer- -c. tetrasomic
Which of the following non disjunction events would give rise to an XYY human?
a. primary non disjunction in the father.
b. primary non disjunction in the mother.
c. secondary non disjunction in the father.
d. secondary non disjunction in the mother.
e. this is the normal chromosome compliment for a human, so non disjunction did not
occur. - correct answer- -c. secondary non disjunction in the mother
A patient with Turner's syndrome (45,X) is found to be colorblind. Both her mother and
father have normal vision. Can we tell whether nondisjunction occurred in her mother or
father?
,a. nondisjunction did not occur.
b. there was nondisjunction, but it could have happened in either the mother or father.
c. nondisjunction occurred in father.
d. nondisjunction occurred in mother.
e. not enough information to determine whether nondisjunction took place or not. -
correct answer- -c. non disjunction occured in the fater
Human monosomics all abort before birth, with the exception of Turner's Syndrome (45,
XO). Why would you expect this monosomic to survive when other monosomics do not?
a. the X chromosome is the smallest, therefore this monosomic is missing very little DNA.
b. normal females have only one functioning X chromosome per cell due to the formation
of Barr bodies;
Turner's syndrome mimics that situation.
c. X chromosomes carry large numbers of lethal genes, therefore a person with only one X
chromosome will have less
chance of getting a lethal gene.
d. unlike autosomes, sex chromosomes only carry information for sex determination, so
one chromosome carries all the information that is necessary.
e. Turner's syndrome is actually due to a trisomic condition; no human monosomics are
known. - correct answer- -b. normal females have only one functioning X chromosome per
cell due to the formation of Barr bodies;
Turner's syndrome mimics that situation.
Cri du chat Syndrome in humans is caused by a (an):
a. trisomic condition.
b. deletion.
c. monosomic condition.
d. paracentric inversion.
, e. reciprocal translocation. - correct answer- -b. deletion
Down Syndrome is _________.
a. a trisomy 21
b. the result of non-disjunction in meiosis
c. 2N=2X=46+1
d. all of the above
e. none of the above - correct answer- -d. all of the above
The probability of a couple having a child afflicted with Down syndrome increases in cases
where the:
a. male parent is less than 20 years old.
b. female parent is less than 20 years old.
c. male parent is more than 40 years old.
d. female parent is more than 40 years old.
e. the probability is the same regardless of the age of either parent. - correct answer- -d.
the female parent is more than 40 years old.
Down syndrome in humans is due to a trisomic condition for chromosome 21. Which of the
following is accurate with respect to this genetic disorder?
a. it is observed more frequently when the mother is under 30 years of age.
b. it is observed more frequently when the father is over 30 years of age.
c. it is never observed when the mother is under 30 years of age.
d. it is observed more frequently when the mother is over 45 years of age.
e. it is always observed when the mother is over 45 years of age. - correct answer- -d. it is
observed more frequently when the mother is over 45 years of age.
