Histology and Cell Biology

Ultrastructure of cells Practice Questions

21 free Ultrastructure of cells practice questions for the USMLE Step 1, each with the correct answer and a detailed explanation. Open any question below, or take the full set as an interactive quiz.

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All Ultrastructure of cells questions

21 questions
  1. Q1. What does the term “cell ultrastructure” refer to in histology and cell biology?
  2. Q2. Which microscopy technique is most commonly used to study the ultrastructure of internal cellular organelles (e.g., mitochondria, ER)?
  3. Q3. Which of the following organelles is characterized ultrastructurally by a double membrane and inner folds called cristae?
  4. Q4. In electron micrographs, which cellular structure appears as a system of flattened membrane-bound sacs (cisternae) typically located near the nucleus and invol…
  5. Q5. Which organelle is characterized ultrastructurally by a network of membrane-bound tubules and cisternae, some of which are studded with ribosomes?
  6. Q6. What ultrastructural feature distinguishes rough ER from smooth ER in electron microscopy images?
  7. Q7. Which of the following organelles is not bound by a membrane according to ultrastructural studies but is abundant in the cytosol and involved in protein synthe…
  8. Q8. Which ultrastructural component provides mechanical support to maintain cell shape and organizes intracellular structure, including positioning of organelles?
  9. Q9. Which ultrastructural feature is most likely to be seen in a cell with active protein secretion (e.g., a plasma cell producing antibodies)?
  10. Q10. Which structure, visible under electron microscopy, regulates transport between the cell nucleus and cytoplasm?
  11. Q11. Which organelle appears as a dark, dense spherical region within the nucleus on electron micrographs and is the site of ribosomal subunit assembly?
  12. Q12. Which ultrastructural organelle is primarily responsible for cellular degradation of worn-out organelles and macromolecules, visible as membrane-bound vesicles…
  13. Q13. Which of the following statements about mitochondria is correct based on ultrastructural and functional properties?
  14. Q14. Which structure is most directly involved in lipid synthesis and detoxification and would appear under EM as a network of smooth tubular membranes lacking ribo…
  15. Q15. Which ultrastructural feature would you expect to see in a cell that is highly active in secretion of glycosylated proteins (e.g., secretory epithelial cell)?
  16. Q16. What advantage does TEM (transmission electron microscopy) provide over light microscopy for studying cell ultrastructure?
  17. Q17. Which of the following correctly matches organelle and its primary function, based on ultrastructural knowledge?
  18. Q18. Which organelle would you expect to be sparse or small in a cell that does not engage in lipid synthesis or detoxification (e.g., mature red blood cell)?
  19. Q19. Which ultrastructural region of a eukaryotic cell is continuous with the perinuclear space and forms an extensive network throughout the cytoplasm?
  20. Q20. Which ultrastructural observation would most strongly suggest a cell is highly metabolically active and producing large amounts of ATP?
  21. Q21. Which ultrastructural feature is most likely to be disrupted in a genetic defect impairing nuclear pore complex formation?