BIOL 331 FINAL EXAM PREP
QUESTIONS & VERIFIED ANSWERS
2026/2027 UPDATE
1. Which of the following best describes the ‘Genomic Equivalence’ principle in
developmental biology?
A. Only germ cells contain the full complement of an organism’s DNA.
B. Different cell types have different genomes due to programmed DNA loss.
C. Stem cells lose genetic information as they differentiate into somatic cells.
D. Every cell in an organism contains the same genes, but only some are expressed.
Answer: D
Conceptual Explanation: Genomic equivalence states that all somatic cells in an organism
contain the same set of genes; differentiation is the result of differential gene expression
rather than gene loss.
2. In Drosophila, which maternal effect gene is responsible for the specification of the
anterior pole by forming a concentration gradient?
A. Nanos
B. Caudal
C. Bicoid
,D. Hunchback
Answer: C
Conceptual Explanation: Bicoid is a maternal mRNA localized at the anterior end of the
egg. It acts as a morphogen to specify anterior structures.
3. The ‘Spemann-Mangold Organizer’ in amphibians induces the formation of which
structures?
A. Ventral mesoderm and endoderm
B. Neural tube and dorsal mesoderm
C. Epidermis and gut tube
D. Extraembryonic membranes
Answer: B
Conceptual Explanation: The organizer, located at the dorsal lip of the blastopore, induces
the surrounding ectoderm to become neural tissue and dorsalizes the mesoderm.
4. What is the primary role of the acrosome reaction during fertilization?
A. To prevent polyspermy by hardening the zona pellucida.
B. To release enzymes that allow the sperm to penetrate the egg’s outer layers.
C. To trigger the completion of meiosis II in the oocyte.
D. To facilitate the fusion of the sperm and egg plasma membranes via Izumo.
, Answer: B
Conceptual Explanation: The acrosome reaction involves the release of proteolytic
enzymes that digest the jelly layer or zona pellucida, allowing the sperm to reach the egg
cell membrane.
5. In vertebrate limb development, which signaling center is responsible for proximal-distal
patterning?
A. Apical Ectodermal Ridge (AER)
B. Dorsal ectoderm
C. Zone of Polarizing Activity (ZPA)
D. Progress Zone (PZ)
Answer: A
Conceptual Explanation: The AER secretes FGFs which maintain the underlying
mesenchyme in a proliferative state, driving the growth and patterning of the limb along
the proximal-distal axis.
6. Which cell type is derived from the neural crest and contributes to the peripheral nervous
system?
A. Oligodendrocytes
B. Astrocytes
C. Schwann cells
QUESTIONS & VERIFIED ANSWERS
2026/2027 UPDATE
1. Which of the following best describes the ‘Genomic Equivalence’ principle in
developmental biology?
A. Only germ cells contain the full complement of an organism’s DNA.
B. Different cell types have different genomes due to programmed DNA loss.
C. Stem cells lose genetic information as they differentiate into somatic cells.
D. Every cell in an organism contains the same genes, but only some are expressed.
Answer: D
Conceptual Explanation: Genomic equivalence states that all somatic cells in an organism
contain the same set of genes; differentiation is the result of differential gene expression
rather than gene loss.
2. In Drosophila, which maternal effect gene is responsible for the specification of the
anterior pole by forming a concentration gradient?
A. Nanos
B. Caudal
C. Bicoid
,D. Hunchback
Answer: C
Conceptual Explanation: Bicoid is a maternal mRNA localized at the anterior end of the
egg. It acts as a morphogen to specify anterior structures.
3. The ‘Spemann-Mangold Organizer’ in amphibians induces the formation of which
structures?
A. Ventral mesoderm and endoderm
B. Neural tube and dorsal mesoderm
C. Epidermis and gut tube
D. Extraembryonic membranes
Answer: B
Conceptual Explanation: The organizer, located at the dorsal lip of the blastopore, induces
the surrounding ectoderm to become neural tissue and dorsalizes the mesoderm.
4. What is the primary role of the acrosome reaction during fertilization?
A. To prevent polyspermy by hardening the zona pellucida.
B. To release enzymes that allow the sperm to penetrate the egg’s outer layers.
C. To trigger the completion of meiosis II in the oocyte.
D. To facilitate the fusion of the sperm and egg plasma membranes via Izumo.
, Answer: B
Conceptual Explanation: The acrosome reaction involves the release of proteolytic
enzymes that digest the jelly layer or zona pellucida, allowing the sperm to reach the egg
cell membrane.
5. In vertebrate limb development, which signaling center is responsible for proximal-distal
patterning?
A. Apical Ectodermal Ridge (AER)
B. Dorsal ectoderm
C. Zone of Polarizing Activity (ZPA)
D. Progress Zone (PZ)
Answer: A
Conceptual Explanation: The AER secretes FGFs which maintain the underlying
mesenchyme in a proliferative state, driving the growth and patterning of the limb along
the proximal-distal axis.
6. Which cell type is derived from the neural crest and contributes to the peripheral nervous
system?
A. Oligodendrocytes
B. Astrocytes
C. Schwann cells
