Cell size and surface area-to-volume ratio Knowledge-Based Practice

Questions

1. 1.

   When a single large cell divides into multiple smaller cells without any change in total cellular volume, what happens to the total surface area available for exchange across the plasma membrane?

   • A) It decreases because individual daughter cells each possess a smaller surface area than the original parent cell.
   • B) It increases, providing a greater combined plasma membrane area for the exchange of materials.
   • C) It remains exactly the same because the overall volume of metabolizing cytoplasm is strictly conserved.
   • D) It decreases initially and then stabilizes at a value lower than the parent cell's initial surface area.
2. 2.

   As a cell increases in size, how does the physical distance between the plasma membrane and the center of the cell change, and how does this affect passive intracellular transport?

   • A) The distance decreases, leading to faster diffusion of nutrients to the cell core.
   • B) The distance decreases, causing metabolic wastes to accumulate more rapidly in the cytoplasm.
   • C) The distance increases, but molecules diffuse at higher velocities to compensate for the greater volume.
   • D) The distance increases, resulting in a substantially longer time required for molecules to reach the cell interior.
3. 3.

   Which of the following cellular adaptations most effectively increases the surface area-to-volume ratio of an active absorptive cell without significantly expanding its internal volume?

   • A) Adopting a spherical shape to minimize edge effects
   • B) Synthesizing thicker layers of cell wall material
   • C) Forming extensive plasma membrane folds such as microvilli
   • D) Expanding internal storage vacuoles to enlarge total volume
4. 4.

   When a spherical cell doubles its radius, what happens to its surface area-to-volume ratio?

   • A) It doubles because the total plasma membrane area quadruples.
   • B) It remains constant because membrane area and internal volume scale at identical rates.
   • C) It decreases to one-fourth of its original value because volume expands sixteenfold.
   • D) It decreases to one-half of its original value because surface area increases fourfold while volume increases eightfold.
5. 5.

   Which of the following statements correctly describes what happens to a cell's surface area-to-volume ratio as it grows, and explains why this change limits maximum cell size?

   • A) The surface area-to-volume ratio increases, which causes the plasma membrane to rupture under osmotic pressure.
   • B) The surface area-to-volume ratio remains constant, which prevents genetic material from regulating organelle synthesis.
   • C) The surface area-to-volume ratio increases, which excessively accelerates the internal diffusion rate of macromolecules.
   • D) The surface area-to-volume ratio decreases, which reduces the efficiency of exchanging nutrients and wastes across the membrane relative to metabolic demand.

Answers and step-by-step solutions appear after you finish the test.