NUMS — Medical & Dental Entry Test
Take the NUMS Biology — Cell Structure and Function (Set 3): 30 multiple-choice questions (40 minutes) with instant scoring and a full answer review.…
What this test covers
The first 5 questions of this test, with the correct answer and explanation.
Q1. A cell has a diameter of 20 µm under a microscope. If the eyepiece is 10× and the objective 40×, how large is the image of the cell (in mm)?
Answer: A. 8
Explanation: Magnification = 400; 20 µm × 400 = 8000 µm = 8 mm.
Q2. A student measures a mitochondrion as 5 mm long in a photomicrograph taken at ×10 000. Its actual length is:
Answer: D. 0.5 µm
Explanation: Actual = 5 mm ÷ 10 000 = 0.0005 mm = 0.5 µm.
Q3. Which feature gives the transmission electron microscope higher resolution than the light microscope?
Answer: C. Electrons have a much shorter wavelength than visible light
Explanation: Resolution depends on wavelength; electron beams have wavelengths far shorter than light.
Q4. A scanning electron microscope is preferred over a TEM when a researcher wants to:
Answer: C. see the surface three-dimensional topography of a specimen
Explanation: SEM scans electrons across the surface and gives 3-D surface images; TEM passes electrons through thin sections.
Q5. During differential centrifugation of a liver homogenate, which organelle fraction pellets FIRST at low speed?
Answer: A. Nuclei
Explanation: The largest, densest components (nuclei and unbroken cells) sediment first; smaller particles need higher speeds.
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Q6. Phospholipid molecules in a bilayer freely move sideways but rarely 'flip-flop' between layers. This is because:
Q7. At low temperature, cholesterol in the animal cell membrane:
Q8. Which membrane component functions mainly in cell-cell recognition?
Q9. Red blood cells placed in distilled water swell and burst. Which term best describes the process?
Q10. A plant cell has a solute potential of −0.8 MPa and a pressure potential of +0.3 MPa. Its water potential is:
Q11. Water will move from cell X (Ψw = −0.6 MPa) to cell Y (Ψw = −0.9 MPa) because:
Q12. In a hypertonic solution a plant cell shows plasmolysis. What fills the space between the shrunken protoplast and the cell wall?
Q13. Glucose enters a red blood cell through a carrier protein down its concentration gradient without ATP. This is:
Q14. The sodium–potassium pump moves ions per cycle as follows:
Q15. Cholera toxin and other ligands often enter cells by receptor-mediated endocytosis. The coated pits are lined by the protein:
Q16. A white blood cell engulfs a bacterium. After the phagosome forms, it fuses with:
Q17. In Tay-Sachs disease, a lysosomal enzyme is missing and a lipid accumulates in neurons. This shows that lysosomes normally:
Q18. A cell actively secreting large amounts of protein, such as a pancreatic acinar cell, would be expected to have well-developed:
Q19. Liver cells of a person on long-term phenobarbital show proliferation of smooth ER. The probable reason is:
Q20. Which sequence correctly shows the pathway of a secretory protein?
Q21. Peroxisomes contain catalase because it:
Q22. Cristae of mitochondria increase surface area for:
Q23. Mitochondria are thought to have originated from engulfed bacteria. Which feature supports this?
Q24. Chromoplasts differ from chloroplasts in that they:
Q25. Which statement about the central vacuole of a mature plant cell is correct?
Q26. Which component is found in the nucleolus?
Q27. Nuclear pores permit all of the following EXCEPT:
Q28. Microtubules are made of:
Q29. A drug that stops spindle fibres from forming (such as colchicine) will block cell division at:
Q30. The '9 + 2' arrangement of microtubules is characteristic of: