39. The term "synapse" has been used to describe the contact points between:

(1) neuronal cells.

(2) immune cells.

(3) epithelial cells.
(A) (1)
(B) (2)
(C) (3)
(D) None of above
(E) All of the above

35. Which of the following descriptions regarding the electrical properties of cellular membranes is correct? (A) If the membrane is impermeable to an ion, the membrane potential approaches the equilibrium potential for that ion. (B) The resting potential in most animal cells is between 20 mV and 120 mV (positive inside). (C) Setting up (or changing) the membrane potential requires changing the bulk concentrations of the ions on the two sides of the membrane. (D) The resting potential decays immediately following the inhibition of the Na+-K+ pump by a drug. (E) None of the above.

36. Which of the following accurately describes the role of Ran-GTP in the directionality of nuclear transport? (A) Ran-GTP is hydrolyzed to Ran-GDP in the cytoplasm, releasing cargo from exportins. (B) The Ran-GTP gradient, maintained by RanGEF in the nucleus and RanGAP in the cytoplasm, ensures unidirectional cargo transport. (C) Ran-GTP directly phosphorylates nuclear transport receptors to facilitate cargo import and export. (D) Ran-GTP binds importin in the cytoplasm to prevent premature cargo release. (E) Ran-GTP hydrolysis occurs exclusively within the nuclear pore complex to control bidirectional movement.

37. Which of the following best explains how proteasomal and lysosomal degradation differ in substrate specificity and regulation? (A) Both systems rely on molecular chaperones, but only lysosomes degrade non-protein cellular components such as lipids. (B) Lysosomes selectively degrade misfolded proteins through autophagy, while proteasomes degrade native proteins marked for turnover. (C) Proteasomes degrade extracellular and cytosolic proteins, while lysosomes are restricted to extracellular material. (D) Proteasomal activity is regulated by lysosomal enzymes, ensuring coordinated protein turnover. (E) Proteasomal degradation requires substrate ubiquitination and ATP hydrolysis, while lysosomal degradation is ubiquitin-independent and primarily pH-dependent.

38. Control of gene expression by Ca2+ can occur through which of the following mechanism? (1) Changes in the transactivating properties of transcription factors following the activation of -dependent kinases.  (2) Changes in the transactivating properties of transcription factors following the activation of -dependent phosphatases.  (3) Translocation of the C-terminal fragment of an L-type channel to the nucleus where it binds to a nuclear transcription factor. (A) (1) (B) (2) (C) (3) (D) All of above are correct (E) None of above is correct

40. Which of the following statement about myelination is incorrect? (A) Myelination is required in both the CNS (central nervous system) and PNS (peripheral nervous system). (B) Myelination involves the ensheathment and insulation of axons by radial glial cell membranes. (C) Myelinating Schwann cells extend their processes to wrap up axons at a 1:1 relationship. (D) Myelinating Oligodendrocytes extend multiple processes that will contact and myelinate several axons. (E) None of above is incorrect.

1. A newly synthesized protein destined for secretion from a eukaryotic cell will generally follow which of the pathways listed below? (A) rough ER → Golgi → transport vesicle → nucleus (B) Golgi → rough ER → lysosome → transport vesicle → plasma membrane (C) rough ER → Golgi → transport vesicle → plasma membrane (D) rough ER → lysosome → transport vesicle → plasma membrane

2. Which of the following structures form cytoplasmic channels that connect adjacent plant cells through the cell walls? (A) desmosomes (B) gap junctions (C) plasmodesmata (D) tight junctions

3. Which of the following statements best describes how unsaturated fatty acids increase membrane fluidity at lower temperatures? (A) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. (B) Unsaturated fatty acids have a higher cholesterol content, which prevents adjacent lipids from packing tightly. (C) Unsaturated fatty acids are more nonpolar than saturated fatty acids. (D) The double bonds block interaction among the hydrophilic head groups of the lipids.

複選題4. Which of the following responses is stimulated by cell signaling the formation of biofilms? (A) formation of mating complexes (B) aggregation of bacteria (C) secretion of substances that inhibit the growth of foreign bacteria (D) inhibition of quorum sensing

5. Upon completion of the citric acid cycle, most of the energy originally stored in each glucose molecule catabolized by cellular respiration is stored in which of the following molecules? (A) acetyl-CoA (B) ATP (C) CO2 (D) NADH