MCQs Transport Across Cell Membrane, Cell Division, Cell Junctions & Cell Communication

(B.Pharm University, GPAT, NIPER, AIIMS Pharmacist, Railway Pharmacist, SSC, ESIC & State Pharmacist Exams)

1. Which transport mechanism requires a carrier protein but does NOT directly utilize ATP?

A. Primary active transport
B. Secondary active transport
C. Facilitated diffusion
D. Endocytosis

Answer: C. Facilitated diffusion

Explanation: Facilitated diffusion uses carrier proteins, but movement occurs down the concentration gradient without ATP expenditure.

2. The Na⁺/K⁺-ATPase pump transports:

A. 2 Na⁺ out and 3 K⁺ in
B. 3 Na⁺ out and 2 K⁺ in
C. 3 Na⁺ in and 2 K⁺ out
D. Equal numbers of Na⁺ and K⁺

Answer: B. 3 Na⁺ out and 2 K⁺ in

Explanation: This electrogenic pump maintains the resting membrane potential.

3. Which of the following is an example of secondary active transport?

A. Na⁺/K⁺ pump
B. GLUT4 transporter
C. Na⁺-glucose cotransporter
D. Aquaporin

Answer: C. Na⁺-glucose cotransporter

Explanation: It utilizes the sodium gradient established by the Na⁺/K⁺ pump.

4. Water movement across a semipermeable membrane due to osmotic pressure is called:

A. Filtration
B. Diffusion
C. Osmosis
D. Pinocytosis

Answer: C. Osmosis

5. Which process is MOST likely to exhibit saturation kinetics?

A. Simple diffusion
B. Osmosis
C. Facilitated diffusion
D. Filtration

Answer: C. Facilitated diffusion

Explanation: Carrier proteins become saturated at high substrate concentrations.

6. Receptor-mediated endocytosis involves:

A. Nonspecific uptake of extracellular fluid
B. Uptake through ligand-receptor interaction
C. Exocytosis of proteins
D. Passive membrane transport

Answer: B. Uptake through ligand-receptor interaction

7. Which membrane transport process can move substances against their concentration gradient?

A. Simple diffusion
B. Facilitated diffusion
C. Active transport
D. Osmosis

Answer: C. Active transport

8. The movement of water through aquaporins is best described as:

A. Primary active transport
B. Secondary active transport
C. Facilitated diffusion
D. Pinocytosis

Answer: C. Facilitated diffusion

9. A red blood cell placed in a hypotonic solution will:

A. Shrink
B. Remain unchanged
C. Swell and may burst
D. Lose water

Answer: C. Swell and may burst

10. Which cellular process is responsible for the uptake of large solid particles?

A. Pinocytosis
B. Phagocytosis
C. Exocytosis
D. Diffusion

Answer: B. Phagocytosis

11. DNA replication occurs during which phase of the cell cycle?

A. G1 phase
B. S phase
C. G2 phase
D. M phase

Answer: B. S phase

12. During mitosis, chromosomes align at the equatorial plate in:

A. Prophase
B. Metaphase
C. Anaphase
D. Telophase

Answer: B. Metaphase

13. Separation of sister chromatids occurs during:

A. Prophase
B. Metaphase
C. Anaphase
D. Telophase

Answer: C. Anaphase

14. Crossing over occurs during:

A. Mitotic prophase
B. Meiotic prophase I
C. Metaphase II
D. Anaphase II

Answer: B. Meiotic prophase I

15. Which meiotic stage is characterized by the pairing of homologous chromosomes?

A. Leptotene
B. Zygotene
C. Diplotene
D. Diakinesis

Answer: B. Zygotene

16. The chromosome number is reduced by half during:

A. Mitosis
B. Meiosis I
C. Meiosis II
D. Cytokinesis

Answer: B. Meiosis I

17. The spindle fibers are primarily composed of:

A. Actin filaments
B. Intermediate filaments
C. Microtubules
D. Collagen fibers

Answer: C. Microtubules

18. Which phase immediately follows DNA synthesis?

A. G1
B. G2
C. Mitosis
D. Cytokinesis

Answer: B. G2

19. A human somatic cell after mitosis produces:

A. Four haploid cells
B. Two diploid cells
C. Four diploid cells
D. Two haploid cells

Answer: B. Two diploid cells

20. Which checkpoint ensures DNA replication is complete before mitosis begins?

A. G1 checkpoint
B. G2 checkpoint
C. Metaphase checkpoint
D. Cytokinesis checkpoint

Answer: B. G2 checkpoint

21. Tight junctions primarily function to:

A. Provide mechanical strength
B. Prevent paracellular diffusion
C. Facilitate cell communication
D. Anchor cells to the basement membrane

Answer: B. Prevent paracellular diffusion

22. Gap junctions allow direct passage of:

A. Proteins only
B. DNA fragments
C. Ions and small molecules
D. Lipids only

Answer: C. Ions and small molecules

23. Desmosomes are particularly abundant in:

A. Cardiac muscle and epidermis
B. Neurons
C. Liver cells only
D. Red blood cells

Answer: A. Cardiac muscle and epidermis

24. Hemidesmosomes attach epithelial cells to:

A. Adjacent epithelial cells
B. Gap junctions
C. Basement membrane
D. Cytoplasm

Answer: C. Basement membrane

25. Which junction is MOST important for synchronized contraction of cardiac muscle?

A. Tight junction
B. Desmosome
C. Gap junction
D. Hemidesmosome

Answer: C. Gap junction

26. Contact-dependent signaling requires:

A. Hormone secretion into the blood
B. Direct cell-to-cell contact
C. Neurotransmitter release
D. Diffusion through extracellular fluid

Answer: B. Direct cell-to-cell contact

27. Which signaling type acts on neighboring cells without entering systemic circulation?

A. Endocrine
B. Synaptic
C. Paracrine
D. Intracrine

Answer: C. Paracrine

28. Nitric oxide signaling is a classic example of:

A. Endocrine signaling
B. Paracrine signaling
C. Synaptic signaling
D. Contact-dependent signaling

Answer: B. Paracrine signaling

29. Neurotransmitters released into the synaptic cleft mediate:

A. Endocrine signaling
B. Paracrine signaling
C. Synaptic signaling
D. Contact signaling

Answer: C. Synaptic signaling

30. Which signaling mechanism typically produces the fastest cellular response?

A. Endocrine
B. Paracrine
C. Synaptic
D. Contact-dependent

Answer: C. Synaptic

31. Insulin acts primarily through:

A. Contact-dependent signaling
B. Synaptic signaling
C. Endocrine signaling
D. Paracrine signaling

Answer: C. Endocrine signaling

32. Which statement regarding endocrine signaling is CORRECT?

A. Signals act only on adjacent cells.
B. Hormones travel through the blood to distant targets.
C. Requires direct membrane contact.
D. Occurs only in neurons.

Answer: B. Hormones travel through blood to distant targets.

33. A signaling molecule affecting the same cell that secreted it is called:

A. Endocrine signaling
B. Synaptic signaling
C. Autocrine signaling
D. Contact-dependent signaling

Answer: C. Autocrine signaling

34. Which of the following is NOT a form of intercellular communication?

A. Contact-dependent
B. Paracrine
C. Endocrine
D. Glycolysis

Answer: D. Glycolysis

35. The major advantage of synaptic signaling over endocrine signaling is:

A. Greater diffusion distance
B. Faster and highly specific communication
C. Longer duration of action
D. Requirement of blood transport

Answer: B. Faster and highly specific communication

36. Ouabain inhibits Na⁺/K⁺-ATPase. Its immediate effect is:

A. Increased K⁺ uptake
B. Increased Na⁺ extrusion
C. Accumulation of intracellular Na⁺
D. Enhanced glucose transport

Answer: C. Accumulation of intracellular Na⁺

37. Which cell junction primarily contributes to the blood-brain barrier?

A. Gap junction
B. Tight junction
C. Desmosome
D. Hemidesmosome

Answer: B. Tight junction

38. During meiosis, genetic diversity mainly results from:

A. Cytokinesis
B. DNA repair
C. Crossing over and independent assortment
D. Chromosome condensation

Answer: C. Crossing over and independent assortment

39. Which transport process is BOTH carrier-mediated and energy-independent?

A. Primary active transport
B. Secondary active transport
C. Facilitated diffusion
D. Endocytosis

Answer: C. Facilitated diffusion

40. A hormone released into the blood and acting on a distant organ is an example of:

A. Synaptic signaling
B. Endocrine signaling
C. Paracrine signaling
D. Juxtacrine signaling

Answer: B. Endocrine signaling

Exam Trap Points

• Simple diffusion: No carrier, no saturation.

• Facilitated diffusion: Carrier-mediated, saturable, no ATP.

• Primary active transport: Direct ATP use.

• Secondary active transport: Uses ion gradient energy.

• Crossing over: Prophase I (Pachytene).

• Chromosome number reduced → Meiosis I

• Tight junction: Barrier function.

• Gap junction: Cell communication.

• Desmosome: Mechanical strength.

• Hemidesmosome: Cell-basement membrane attachment.

• Paracrine: Nearby cells.

• Synaptic: Neuron to target cell.

• Endocrine: Hormones via blood.

• Contact-dependent (juxtacrine): Direct membrane contact.

Dr Alok Singh