NUMS — Medical & Dental Entry Test

NUMS Biology — Cell Structure and Function (Set 1)

Take the NUMS Biology — Cell Structure and Function (Set 1): 30 multiple-choice questions (40 minutes) with instant scoring and a full answer review.…

What this test covers

30 NUMS Biology

Sample questions with answers

The first 5 questions of this test, with the correct answer and explanation.

Q1. A cell from a pancreatic acinus secretes large amounts of digestive enzymes. Which organelles would you expect to be especially abundant in it?
- A. Smooth endoplasmic reticulum and lysosomes
- B. Centrioles and cilia
- C. Rough endoplasmic reticulum and Golgi apparatus ✓
- D. Chloroplasts and peroxisomes
Answer: C. Rough endoplasmic reticulum and Golgi apparatus
Explanation: Secreted proteins are made on RER ribosomes and packaged/modified by the Golgi before exocytosis.
Q2. Liver cells of a person who regularly takes sedative drugs show an enlarged network of membranes without ribosomes. This organelle helps by:
- A. Producing ATP by oxidative phosphorylation
- B. Detoxifying drugs through enzymes of the smooth ER ✓
- C. Synthesising digestive enzymes on its surface
- D. Packaging hydrolytic enzymes into lysosomes
Answer: B. Detoxifying drugs through enzymes of the smooth ER
Explanation: Smooth ER contains detoxifying enzymes (e.g. cytochrome P450) and proliferates in response to repeated drug exposure.
Q3. A researcher argues that mitochondria were once free-living bacteria engulfed by an ancestral cell. Which finding would best support this claim?
- A. They contain circular DNA and 70S ribosomes similar to bacteria ✓
- B. They are synthesised entirely by the Golgi apparatus
- C. They are surrounded by a single membrane
- D. They lack any genetic material of their own
Answer: A. They contain circular DNA and 70S ribosomes similar to bacteria
Explanation: Mitochondria have their own circular DNA, 70S ribosomes, double membranes and divide by binary fission, like bacteria.
Q4. In Tay-Sachs disease, lipids accumulate in nerve cells because a hydrolytic enzyme is missing. Which organelle is defective?
- A. Centriole
- B. Ribosome
- C. Nucleolus
- D. Lysosome ✓
Answer: D. Lysosome
Explanation: Tay-Sachs is a lysosomal storage disorder: lack of a lysosomal enzyme (hexosaminidase A) causes gangliosides to build up.
Q5. A cell is treated with a drug that destroys the nucleolus. Which process will be affected first?
- A. Formation of the nuclear envelope
- B. Assembly of ribosomal subunits ✓
- C. DNA replication
- D. Breakdown of fatty acids
Answer: B. Assembly of ribosomal subunits
Explanation: The nucleolus synthesises rRNA and assembles ribosomal subunits, so protein synthesis capacity falls.

The other 25 questions

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Q6. Which feature is found in prokaryotic cells but NOT in eukaryotic animal cells?
- A. Membrane-bound nucleus
- B. Peptidoglycan cell wall
- C. Mitochondria
- D. 80S ribosomes in the cytoplasm
Q7. According to the fluid mosaic model, the 'mosaic' part refers to:
- A. Carbohydrates attached to the cytoskeleton
- B. Lateral movement of phospholipids
- C. Cholesterol making the membrane rigid
- D. Proteins scattered within and across the phospholipid bilayer
Q8. Cholesterol in animal cell membranes helps to:
- A. Provide the main source of membrane energy
- B. Bind antigens on the outer surface
- C. Regulate membrane fluidity over a range of temperatures
- D. Act as a channel for glucose transport
Q9. Red blood cells placed in a solution swell and burst. The external solution was:
- A. A concentrated salt solution
- B. Isotonic to the cytoplasm
- C. Hypertonic to the cytoplasm
- D. Hypotonic to the cytoplasm
Q10. A plant cell placed in concentrated sucrose solution shows the protoplast pulled away from the cell wall. The space between wall and membrane is filled with:
- A. Air
- B. The external sucrose solution
- C. Pure water from the vacuole
- D. Cytoplasm
Q11. Glucose enters a cell down its concentration gradient through a carrier protein without using ATP. This is:
- A. Pinocytosis
- B. Active transport
- C. Facilitated diffusion
- D. Simple diffusion through the bilayer
Q12. The sodium–potassium pump is described as electrogenic because it:
- A. Moves equal numbers of Na⁺ and K⁺ in opposite directions
- B. Uses light energy to move ions
- C. Moves 3 Na⁺ out and 2 K⁺ in per ATP, creating a net charge difference
- D. Carries ions down their concentration gradients
Q13. White blood cells engulf bacteria by extending pseudopodia around them. This process is:
- A. Phagocytosis
- B. Pinocytosis
- C. Facilitated diffusion
- D. Exocytosis
Q14. Which statement about the Golgi apparatus is correct?
- A. It synthesises proteins on attached ribosomes
- B. Vesicles from ER fuse with its cis face, and secretory vesicles bud from its trans face
- C. It is the site of the Krebs cycle
- D. It is absent from secretory cells
Q15. A protein labelled with a radioactive amino acid is tracked in a secretory cell. The correct order in which the label appears is:
- A. Nucleus → smooth ER → mitochondria → membrane
- B. Golgi apparatus → rough ER → lysosome → nucleus
- C. Rough ER → Golgi apparatus → secretory vesicles → cell membrane
- D. Cell membrane → Golgi → rough ER → vesicles
Q16. Which cytoskeletal element forms the spindle fibres during cell division and the core of cilia?
- A. Intermediate filaments
- B. Microfilaments
- C. Microtubules
- D. Collagen fibres
Q17. Muscle contraction and cytoplasmic streaming depend mainly on which cytoskeletal protein?
- A. Spectrin
- B. Keratin
- C. Tubulin
- D. Actin
Q18. In plant cells, peroxisomes and glyoxysomes are similar because both:
- A. Are produced by the nucleolus
- B. Have double membranes and their own DNA
- C. Are single-membrane microbodies containing oxidative enzymes
- D. Contain chlorophyll
Q19. A cell with a high surface area to volume ratio will:
- A. Need a larger nucleus
- B. Lose water more slowly
- C. Have fewer membrane proteins per unit volume
- D. Exchange materials with its surroundings more efficiently
Q20. Which pair correctly matches the organelle with its double-membrane property?
- A. Ribosome and centriole — both double-membrane bound
- B. Lysosome and vacuole — both double-membrane bound
- C. Golgi and ER — both double-membrane bound
- D. Nucleus and chloroplast — both double-membrane bound
Q21. The cristae of mitochondria increase:
- A. The surface area for electron transport chain proteins and ATP synthase
- B. The volume of matrix for glycolysis
- C. The storage of starch
- D. The number of ribosomes
Q22. Electron microscopes give more detailed images than light microscopes mainly because electrons:
- A. Travel more slowly than light
- B. Can be used to view living cells
- C. Produce coloured images
- D. Have a much shorter wavelength, giving higher resolution
Q23. Which component would be absent in a mature mammalian red blood cell?
- A. Haemoglobin
- B. Carbonic anhydrase
- C. Nucleus
- D. Plasma membrane
Q24. Plasmodesmata in plant cells are functionally similar to which junctions in animal cells?
- A. Gap junctions
- B. Synaptic clefts
- C. Tight junctions
- D. Desmosomes
Q25. The middle lamella between two adjacent plant cells is composed mainly of:
- A. Cellulose microfibrils
- B. Calcium and magnesium pectates
- C. Chitin
- D. Lignin and suberin
Q26. Which statement about ribosomes is correct?
- A. Prokaryotic ribosomes are 80S with 50S and 30S subunits
- B. Ribosomes are found only attached to the ER
- C. Eukaryotic cytoplasmic ribosomes are 80S, made of 60S and 40S subunits
- D. Ribosomes are surrounded by a single membrane
Q27. A cell actively accumulates iodide ions to a concentration 30 times higher than in blood. Poisoning the cell with cyanide would:
- A. Make the cell burst immediately
- B. Increase iodide uptake by diffusion
- C. Have no effect since uptake is passive
- D. Stop iodide accumulation because ATP production stops
Q28. Centrioles are absent in the cells of most higher plants. Which statement is therefore correct?
- A. Higher plant cells can still form a spindle without centrioles
- B. Spindles in plants are made of actin
- C. Higher plant cells cannot divide by mitosis
- D. Higher plant cells divide only by amitosis
Q29. Chromatin condensed into darkly staining, transcriptionally inactive regions is called:
- A. Euchromatin
- B. Nucleolus
- C. Heterochromatin
- D. Nucleoplasm
Q30. Which molecules on the outer surface of the cell membrane are mainly involved in cell recognition?
- A. Cholesterol molecules
- B. Peripheral proteins on the inner side
- C. Phospholipid tails
- D. Glycoproteins and glycolipids