USABO OPEN EXAM 20
QUESTIONS AND COMPLETE
SOLUTIONS GRADED A+
Your Exam Plug
,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?
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?
, 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.
E. Both 5′ caps and poly-A tails inhibit the degradation of the mRNA molecule in the cytosol. - Answer: C.
Recognition of splice sites by the spliceosome is based on the physical conformation of the mRNA
strand, not on any specific consensus sequence.
Cellular metabolism is bidirectional and complex. Indicate whether the following statements concerning
the metabolic capabilities of a nucleated human cell are True or False.
A. Can convert sugars to fats
B. Can convert fats to sugars
C. Can convert sugars to amino acids
D. Can convert amino acids to sugars - Answer: A. True
B. False
C. True
D. True
QUESTIONS AND COMPLETE
SOLUTIONS GRADED A+
Your Exam Plug
,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?
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?
, 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.
E. Both 5′ caps and poly-A tails inhibit the degradation of the mRNA molecule in the cytosol. - Answer: C.
Recognition of splice sites by the spliceosome is based on the physical conformation of the mRNA
strand, not on any specific consensus sequence.
Cellular metabolism is bidirectional and complex. Indicate whether the following statements concerning
the metabolic capabilities of a nucleated human cell are True or False.
A. Can convert sugars to fats
B. Can convert fats to sugars
C. Can convert sugars to amino acids
D. Can convert amino acids to sugars - Answer: A. True
B. False
C. True
D. True
