Which concept describes size limitations on cells due to surface area to volume ratio?

• A. Size limitations on cells
• B. Protein synthesis
• C. Ribosome
• D. Lysosomes

Answer: (A)

Surface area to volume ratio limits how large a cell can become. As a cell grows, its volume increases much faster than its surface area, so the membrane cannot supply enough surface area for the necessary diffusion of nutrients in and wastes out. When the ratio gets too low, transport across the membrane can’t meet metabolic demands, making the cell less efficient or unable to sustain itself. That’s why cells remain small or develop ways to increase surface area relative to volume. The other terms refer to cellular machinery or organelles involved in protein production or digestion, not to the size limitation imposed by transport, so they don’t describe this concept.