USABO Open Exam 2025/2026 Exam
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Why is myelin important in the nervous system?
A. It allows signals to travel faster along axons because depolarization
occurs only at myelinated locations.
B. It allows signals to travel faster along axons because depolarization
occurs only at nonmyelinated locations.
C. It bundles the dendrites of adjacent neurons together.
D. It increases capacitance across the cell membrane, which helps
electrical signals to leave the axons.
E. It traps neurotransmitters, increasing their concentrations in the synaptic
cleft. - 🧠 ANSWER ✔✔B
Which type of cytoskeletal fiber is the primary building block of eukaryotic
cilia and flagella?
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,A. Actin microfilaments.
B. Intermediate filaments.
C. Keratin.
D. Microtubules.
E. RNA. - 🧠 ANSWER ✔✔D. Microtubules.
Which of the following human cell types contains the LEAST amount of
RNA involved in splicing?
A. Lymphocytes
B. Lymphoblasts
C. Erythrocytes
D. Erythroblasts
E. Hepatocytes - 🧠 ANSWER ✔✔C. Erythrocytes
Antimicrobial drugs, also known as antibiotics, inhibit the growth of bacteria
by targeting cellular components present in bacteria. Which of the following
cellular components is NOT a valid antimicrobial drug target?
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, A. Centrosome.
B. Ribosome.
C. Cell wall.
D. RNA polymerase.
E. DNA polymerase - 🧠 ANSWER ✔✔A. Centrosome.
Which of the following statements concerning the nature of post-
transcriptional processing of mRNA is INCORRECT?
A. The presence of introns is a derived trait of eukaryotes.
B. Mitochondrial mRNA lacks a 5′ cap because capping is a strictly
intranuclear process.
C. Recognition of splice sites by the spliceosome is based on the physical
conformation of the mRNA strand, not on any specific consensus
sequence.
D. In some genes, poly-A tails can generate genetic diversity by being
added at one of multiple possible sites on the mRNA transcript.
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
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PRIVACY STATEMENT. ALL RIGHTS RESERVED
Questions and Answers 100%
Guaranteed Success | Already Rated A+
Why is myelin important in the nervous system?
A. It allows signals to travel faster along axons because depolarization
occurs only at myelinated locations.
B. It allows signals to travel faster along axons because depolarization
occurs only at nonmyelinated locations.
C. It bundles the dendrites of adjacent neurons together.
D. It increases capacitance across the cell membrane, which helps
electrical signals to leave the axons.
E. It traps neurotransmitters, increasing their concentrations in the synaptic
cleft. - 🧠 ANSWER ✔✔B
Which type of cytoskeletal fiber is the primary building block of eukaryotic
cilia and flagella?
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
1
PRIVACY STATEMENT. ALL RIGHTS RESERVED
,A. Actin microfilaments.
B. Intermediate filaments.
C. Keratin.
D. Microtubules.
E. RNA. - 🧠 ANSWER ✔✔D. Microtubules.
Which of the following human cell types contains the LEAST amount of
RNA involved in splicing?
A. Lymphocytes
B. Lymphoblasts
C. Erythrocytes
D. Erythroblasts
E. Hepatocytes - 🧠 ANSWER ✔✔C. Erythrocytes
Antimicrobial drugs, also known as antibiotics, inhibit the growth of bacteria
by targeting cellular components present in bacteria. Which of the following
cellular components is NOT a valid antimicrobial drug target?
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
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PRIVACY STATEMENT. ALL RIGHTS RESERVED
, A. Centrosome.
B. Ribosome.
C. Cell wall.
D. RNA polymerase.
E. DNA polymerase - 🧠 ANSWER ✔✔A. Centrosome.
Which of the following statements concerning the nature of post-
transcriptional processing of mRNA is INCORRECT?
A. The presence of introns is a derived trait of eukaryotes.
B. Mitochondrial mRNA lacks a 5′ cap because capping is a strictly
intranuclear process.
C. Recognition of splice sites by the spliceosome is based on the physical
conformation of the mRNA strand, not on any specific consensus
sequence.
D. In some genes, poly-A tails can generate genetic diversity by being
added at one of multiple possible sites on the mRNA transcript.
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
3
PRIVACY STATEMENT. ALL RIGHTS RESERVED
