AP Biology · Topic 2.3
Cell Size Practice
Part of Cell Structure and Function.(ENE-1.C)
Practice questions
7
Sample questions
5 of 7 — sign in to practice the rest with adaptive difficulty and mastery tracking.
Sample 1difficulty 2/5
Cells are typically small because as they grow,
- A
Membranes thicken and progressively block the diffusion of nutrients inward across the surface
- B
Surface area increases faster than volume, overwhelming transport
- Ccheck_circle
Volume increases faster than surface area, limiting exchange across membranes
- D
DNA replication slows down dramatically as cytoplasmic volume expands inside the cell
Why
Volume scales with r³ but surface area with r². Larger cells can't move enough material across their membranes per unit volume.
- A
Sample 2difficulty 2/5
Which structural feature increases a cell's surface-area-to-volume ratio for efficient absorption?
- A
Smooth ER
- Bcheck_circle
Microvilli
- C
Centrioles
- D
Nucleolus
Why
Microvilli are finger-like membrane projections (e.g., on intestinal epithelial cells) that dramatically expand absorptive surface.
- A
Sample 3difficulty 2/5
Approximate ordering by size (smallest to largest) is
- A
Bacterium, virus, animal cell
- B
Animal cell, bacterium, virus
- Ccheck_circle
Virus, bacterium, animal cell
- D
Same size
Why
Virus (<del>50 nm) << bacterium (</del>1 µm) << eukaryotic cell (~10 µm). Each scale step is roughly 10× larger.
- A
Sample 4difficulty 3/5
Intestinal absorptive cells take up large amounts of glucose and amino acids per minute. EM images show their apical surfaces are densely packed with finger-like protrusions called microvilli. A textbook claims this increases absorption per unit area.
Which statement BEST explains the functional advantage of microvilli for these cells?
- A
They allow the cell to switch between active and passive transport
- Bcheck_circle
They increase the surface area available for transport without increasing cell volume
- C
They reduce overall surface area to limit ion leakage
- D
They increase the volume of the cell while keeping surface area constant
Why
Microvilli amplify membrane area; transport proteins on a larger surface boost net flux of nutrients without altering cell volume.
- A
Sample 5difficulty 3/5
Three agar cubes (1, 2, 3 cm sides) in 0.1 M NaOH.
Which biological principle does this experiment illustrate?
- A
Diffusion does not depend on geometry
- B
Cubic cells exist in nature
- Ccheck_circle
Cells must remain small (or have folded membranes) to maintain efficient exchange with their environment
- D
Larger cells have higher diffusion rates
Why
As size increases, volume grows as L^3 while surface as L^2. The decreasing SA:V ratio limits exchange efficiency. This is why cells are small or have specialized surface elaborations (microvilli, alveoli, root hairs) to maintain exchange.
- A