A spherical bacterial cell has a radius of 3 pm. The human egg cell has a radius of 100 pm.

Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation?

A) the egg cell, because it has the smallest surface-to-volume-ratio

B) the egg cell, because it has the largest surface-to-volume-ratio

C) the bacterial cell, because it has the smallest surface-to-volume-ratio

D) the bacterial cell, because it has the largest surface-to-volume-ratio

The bacterial cell because it has the largest surface-to-volume-ratio.

Explanation:

The rate of diffusion in and out of a body depends on surface area to volume ratio. The higher the ratio the greater the rate of diffusion and the lower the ratio, the lower the rate of diffusion.

This implies that small organisms like the bacteria cell expose a large surface area to the surrounding when compared to big organism cells. Therefore, small organisms depend on diffusion as a means of transport of foods, respiratory gases and waste products.

Large organisms, in addition to diffusion have trasnport systems to increase the efficiency of diffusion.