Genetics exam test questions and
answers graded A+
What is the universal biological definition of a "female" organism?
A) Female organisms always have two X chromosomes.
B) Females are the smaller of the two sexes.
C) Females produce larger gametes compared with males.
D) Females carry and bear live offspring.
E) All of the above are true. - ANS✅✅C) Females produce larger gametes compared with males.
Unlike most animals, male bees produce sperm using mitosis, not meiosis. This is because male bees
are _______ organisms.
A) heterogametic
B) homogametic
C) diploid
D) haploid
E) trisomic - ANS✅✅D) haploid
A human sperm contains ___ autosomes and ___ sex chromosomes.
A) 22 ; 1
B) 22 ; 2
C) 23 ; 2
D) 44 ; 2
E) 46 ; 1 - ANS✅✅A) 22 ; 1
Based on what you know about X chromosome inactivation in humans, you should conclude that all
genes on the human X chromosome are _____.
A) isogamous
B) anisogamous
C) haplosufficient
D) haploinsufficient
, E) homogametic - ANS✅✅C) haplosufficient
Using new genetic engineering techniques, you are able to create a Drosophila zygote with four X
chromosomes, four Y chromosomes, and four copies of each autosome. Based on what you know
about Drosophila sex determination, what sexual phenotype should this fly display?
A) It should have both male and female genitals.
B) It should have female genitals.
C) It should have male genitals.
D) It should have no sexual characteristics.
E) There is a 50:50 chance that it will be male or female. - ANS✅✅B) It should have female
genitals.
Which of the following is true about genes on the Drosophila X chromosome?
A) They are all involved in female sex development.
B) They are all involved in male sex development.
C) They are upregulated in male flies.
D) They are downregulated in female flies.
They are randomly inactivated in the early embryo. - ANS✅✅C) They are upregulated in male flies.
You have a red molecule that specifically binds to inactivated X chromosomes (Barr bodies), and a
blue molecule that binds to all X chromosomes. You apply these two molecules to cheek cells from
an atypical human male with an XXXY karyotype. When looking at these cells under the microscope,
you should see ___ red signals and ___ blue signals in the nucleus of each cell.
A) 0 ; 1
B) 0 ; 3
C) 1 ; 3
D) 2 ; 3
E) 3 ; 3 - ANS✅✅D) 2 ; 3
The Drosophila yellow gene is located on the X chromosome, and it is haplosufficient. Wild-type flies
have gray bodies, and flies with homozygous loss-of-function yellow alleles have yellow bodies. You
cross a true-breeding gray female to a yellow male. What ratio of phenotypes and sexes should you
expect in their offspring?
A) 1:1 yellow females : gray males
answers graded A+
What is the universal biological definition of a "female" organism?
A) Female organisms always have two X chromosomes.
B) Females are the smaller of the two sexes.
C) Females produce larger gametes compared with males.
D) Females carry and bear live offspring.
E) All of the above are true. - ANS✅✅C) Females produce larger gametes compared with males.
Unlike most animals, male bees produce sperm using mitosis, not meiosis. This is because male bees
are _______ organisms.
A) heterogametic
B) homogametic
C) diploid
D) haploid
E) trisomic - ANS✅✅D) haploid
A human sperm contains ___ autosomes and ___ sex chromosomes.
A) 22 ; 1
B) 22 ; 2
C) 23 ; 2
D) 44 ; 2
E) 46 ; 1 - ANS✅✅A) 22 ; 1
Based on what you know about X chromosome inactivation in humans, you should conclude that all
genes on the human X chromosome are _____.
A) isogamous
B) anisogamous
C) haplosufficient
D) haploinsufficient
, E) homogametic - ANS✅✅C) haplosufficient
Using new genetic engineering techniques, you are able to create a Drosophila zygote with four X
chromosomes, four Y chromosomes, and four copies of each autosome. Based on what you know
about Drosophila sex determination, what sexual phenotype should this fly display?
A) It should have both male and female genitals.
B) It should have female genitals.
C) It should have male genitals.
D) It should have no sexual characteristics.
E) There is a 50:50 chance that it will be male or female. - ANS✅✅B) It should have female
genitals.
Which of the following is true about genes on the Drosophila X chromosome?
A) They are all involved in female sex development.
B) They are all involved in male sex development.
C) They are upregulated in male flies.
D) They are downregulated in female flies.
They are randomly inactivated in the early embryo. - ANS✅✅C) They are upregulated in male flies.
You have a red molecule that specifically binds to inactivated X chromosomes (Barr bodies), and a
blue molecule that binds to all X chromosomes. You apply these two molecules to cheek cells from
an atypical human male with an XXXY karyotype. When looking at these cells under the microscope,
you should see ___ red signals and ___ blue signals in the nucleus of each cell.
A) 0 ; 1
B) 0 ; 3
C) 1 ; 3
D) 2 ; 3
E) 3 ; 3 - ANS✅✅D) 2 ; 3
The Drosophila yellow gene is located on the X chromosome, and it is haplosufficient. Wild-type flies
have gray bodies, and flies with homozygous loss-of-function yellow alleles have yellow bodies. You
cross a true-breeding gray female to a yellow male. What ratio of phenotypes and sexes should you
expect in their offspring?
A) 1:1 yellow females : gray males
