BIO 351
BIO 351 - Final Exam Practice Fall 2025 Questions
With Correct Detailed Answers
Which of the following is a mechanism underlying the teratogenic defects found in embryos exposed to
alcohol?
a. Increased neural crest cell proliferation.
b. lncreased neural cell adhesion mediated by protein L1.
c. lmpaired myoblast migration and differentiation.
d. lncreased apoptosis of developing neurons. - ANSWER ✔ - d. Increased apoptosis of developing
neurons.
You have discovered that a pesticide binds to the estrogen receptor, blocking estrogen from binding, and
it does not turn on the normal genes associated with estrogen signaling. This is an example of which type
of endocrine disruptor?
a. mimic.
b. trigger.
c. blocker. - ANSWER ✔ - c. blocker.
A farmer has several ewes that ate skunk cabbage or California hellebore while they were pregnant.
What potential developmental defects will be detected in their lambs?
a. cyclopia and holoprosencephaly.
b. axial skeletal defects.
c. Mullerian duct defects.
d. Shortened limbs. - ANSWER ✔ - a. cyclopia and holoprosencephaly.
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, BIO 351
When a female embryo is exposed to diethylstilbestrol it acts to block _______ expression, which in turn,
leads to altered ______ expression and patterning of the female reproductive tract. Fill in the blanks.
a. Wnt5 & Notch.
b. Wnt7, Hoxa10 and Hoxa11.
c. Estrogen; Hoxa10.
d. Hoxa10; Hoxa11. - ANSWER ✔ - b. Wnt7, Hoxa10 and Hoxa11.
You have a patient with a T shaped uterus, obstructed Fallopian tubes and clear cell adenocarcinoma of
the cervix. You believe that she was exposed to a teratogen en utero. Which of the following is the most
likely chemical compound?
a. Vinclozolin.
b. Thalidomide.
c. Diethylstilbesterol (DES).
d. Valproic acid. - ANSWER ✔ - c. Diethylstilbesterol (DES).
What is the embryological origin of the malleus, incus and stapes?
A. Endoderm.
B. Neural crest.
C. Head surface ectoderm.
D. Mesodermal mesenchyme.
E. Neural tube ectoderm. - ANSWER ✔ - B. Neural Crest.
The diagram below demonstrates the reactions catalyzed by aromatase. lf Trachemys scripta embryos
are cultured at 31C, the clutch of hatchlings should be 100% female. lf there is a mutation in aromatase
so that it is only 50% efficient at 31C what is most likely happen to the sex ratio of the clutch?
A. 100% male
B. 50% female
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, BIO 351
C. 100% female - ANSWER ✔ - B. 50% female.
ln Hymenopteran insects such as bees, which of the following best describes their mode of sex
determination?
A. Sex is determined by aromatase function.
B. There is a single gene locus that determines sex.
C. Sex is environmentally determined.
D. They have sex chromosomes. - ANSWER ✔ - B. There is a single gene locus that determines sex.
In Drosophila how does Sex lethal (Sx/) regulate sex determination?
A lt regulates mRNA splicing.
B. lt regulates spermatogenesis.
C. It activates the X chromosome early promoter for Scute and Sisterless-4.
D. lt regulates estrogen synthesis. - ANSWER ✔ - A. It regulates mRNA splicing.
Fill in the blanks. During embryonic development ________ and __________ are necessary to initiate the
ovarian program of development and they induce expression of _______.
A. Wt1, Sry, Wnt4.
B. B-catenin, Dax1, Sox9.
C. B-catenin, Sry, Sox9.
D. Rspo1, Wnt4, B-catenin. - ANSWER ✔ - D. Rspo1, Wnt4, B-catenin
You have an XY female mouse with an intact SRY gene. Which of the following genes do you think is most
likely mutated in this animal?
A. Sox9.
B. B-catenin.
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BIO 351 - Final Exam Practice Fall 2025 Questions
With Correct Detailed Answers
Which of the following is a mechanism underlying the teratogenic defects found in embryos exposed to
alcohol?
a. Increased neural crest cell proliferation.
b. lncreased neural cell adhesion mediated by protein L1.
c. lmpaired myoblast migration and differentiation.
d. lncreased apoptosis of developing neurons. - ANSWER ✔ - d. Increased apoptosis of developing
neurons.
You have discovered that a pesticide binds to the estrogen receptor, blocking estrogen from binding, and
it does not turn on the normal genes associated with estrogen signaling. This is an example of which type
of endocrine disruptor?
a. mimic.
b. trigger.
c. blocker. - ANSWER ✔ - c. blocker.
A farmer has several ewes that ate skunk cabbage or California hellebore while they were pregnant.
What potential developmental defects will be detected in their lambs?
a. cyclopia and holoprosencephaly.
b. axial skeletal defects.
c. Mullerian duct defects.
d. Shortened limbs. - ANSWER ✔ - a. cyclopia and holoprosencephaly.
1|P a g e
, BIO 351
When a female embryo is exposed to diethylstilbestrol it acts to block _______ expression, which in turn,
leads to altered ______ expression and patterning of the female reproductive tract. Fill in the blanks.
a. Wnt5 & Notch.
b. Wnt7, Hoxa10 and Hoxa11.
c. Estrogen; Hoxa10.
d. Hoxa10; Hoxa11. - ANSWER ✔ - b. Wnt7, Hoxa10 and Hoxa11.
You have a patient with a T shaped uterus, obstructed Fallopian tubes and clear cell adenocarcinoma of
the cervix. You believe that she was exposed to a teratogen en utero. Which of the following is the most
likely chemical compound?
a. Vinclozolin.
b. Thalidomide.
c. Diethylstilbesterol (DES).
d. Valproic acid. - ANSWER ✔ - c. Diethylstilbesterol (DES).
What is the embryological origin of the malleus, incus and stapes?
A. Endoderm.
B. Neural crest.
C. Head surface ectoderm.
D. Mesodermal mesenchyme.
E. Neural tube ectoderm. - ANSWER ✔ - B. Neural Crest.
The diagram below demonstrates the reactions catalyzed by aromatase. lf Trachemys scripta embryos
are cultured at 31C, the clutch of hatchlings should be 100% female. lf there is a mutation in aromatase
so that it is only 50% efficient at 31C what is most likely happen to the sex ratio of the clutch?
A. 100% male
B. 50% female
2|P a g e
, BIO 351
C. 100% female - ANSWER ✔ - B. 50% female.
ln Hymenopteran insects such as bees, which of the following best describes their mode of sex
determination?
A. Sex is determined by aromatase function.
B. There is a single gene locus that determines sex.
C. Sex is environmentally determined.
D. They have sex chromosomes. - ANSWER ✔ - B. There is a single gene locus that determines sex.
In Drosophila how does Sex lethal (Sx/) regulate sex determination?
A lt regulates mRNA splicing.
B. lt regulates spermatogenesis.
C. It activates the X chromosome early promoter for Scute and Sisterless-4.
D. lt regulates estrogen synthesis. - ANSWER ✔ - A. It regulates mRNA splicing.
Fill in the blanks. During embryonic development ________ and __________ are necessary to initiate the
ovarian program of development and they induce expression of _______.
A. Wt1, Sry, Wnt4.
B. B-catenin, Dax1, Sox9.
C. B-catenin, Sry, Sox9.
D. Rspo1, Wnt4, B-catenin. - ANSWER ✔ - D. Rspo1, Wnt4, B-catenin
You have an XY female mouse with an intact SRY gene. Which of the following genes do you think is most
likely mutated in this animal?
A. Sox9.
B. B-catenin.
3|P a g e
