The diffusion rate for essential molecules limits cell size because of the \( \mathrm{SA}: \mathrm{V} \) of the cell. Small molecules can move through the cell cytoplasm via simple diffusion. \( S A: V \) is directly related to the efficiency of diffusion through the cell. True False SA:V can be calculated by multiplying the surface area of the cell by the

The statement is **True**. The surface area to volume ratio (SA:V) is indeed a critical factor in determining the efficiency of diffusion within a cell. As a cell grows larger, its volume increases at a faster rate than its surface area, leading to a lower SA:V ratio. This lower ratio can limit the rate at which essential molecules can diffuse into and out of the cell, thereby affecting cellular functions. To clarify the calculation of SA:V: 1. **Surface Area (SA)**: For a spherical cell, the surface area can be calculated using the formula: \[ SA = 4\pi r^2 \] where \( r \) is the radius of the cell. 2. **Volume (V)**: The volume of a spherical cell is calculated using the formula: \[ V = \frac{4}{3}\pi r^3 \] 3. **SA:V Ratio**: The SA:V ratio can then be expressed as: \[ \frac{SA}{V} = \frac{4\pi r^2}{\frac{4}{3}\pi r^3} = \frac{3}{r} \] This shows that as the radius \( r \) increases, the SA:V ratio decreases, which is why smaller cells are generally more efficient at diffusion. In summary, the statement is true, and the SA:V ratio is calculated by dividing the surface area by the volume of the cell.