Final answer:
Rapid Replication is not a fundamental reason why cells need to remain small; rather, crucial factors include Efficient Nutrient Exchange, High Surface Area-to-Volume Ratio, and Effective Waste Removal.
Step-by-step explanation:
The reason why cells need to remain small that is not accurate is Rapid Replication. While rapid replication is beneficial and often a result of smaller cell sizes, it is not a fundamental reason why cells must be small. Essential reasons include Efficient Nutrient Exchange, a High Surface Area-to-Volume Ratio, and Effective Waste Removal. Cells must remain small to ensure adequate surface area for the diffusion of nutrients and waste products. A larger cell would have a smaller surface area relative to its volume, which can hinder the cell's ability to exchange nutrients and remove waste efficiently.
Comparing cells based on surface area-to-volume ratios, a spherical cell with a diameter of 5 µm would likely exchange nutrients and wastes more efficiently than a cube-shaped cell with a side length of 7 µm. This is quantified by calculating their respective surface area-to-volume ratios, which demonstrate that the sphere has a higher ratio and thus a better capacity for exchange through its cell membrane relative to its volume.