Surface Area to Volume Ratio for a Cube

Steps:

• Side length a = 2 μm for the cube-shaped cell.
• Surface area = 6a² = 6 × (2)² = 24 μm².
• Volume = a³ = (2)³ = 8 μm³.
• Ratio = surface area : volume = 24 : 8 = 3 : 1.

Why D is correct:

• For a cube, the surface area to volume ratio is 6/a; with a = 2 μm, this equals 3:1 per the formula.

Why the others are wrong:

• A: 1:2 underestimates the ratio, as it implies a larger side length like 6 μm.
• B: 1:3 further underestimates, fitting an even larger cube like 9 μm side.
• C: 2:1 overestimates, as it would require a smaller side like 3 μm.

Final answer: D