USABO Open Exam 2024 | 100%Correct Answers Verified Latest 2024 Version.

USABO Open Exam 2024 | 100%Correct Answers Verified Latest 2024 Version. 1. 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. 2. 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. 3. 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 Page 2 4. 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. 5. 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.