AP Biology Cell Size

AP Biology: Cell Surface Area to Volume Ratio

by Regina Katz

​Why are smaller cells more effective in the transport of nutrients and wastes than larger cells?

Multiple Choice

In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion?

• The cuboidal cell

• The tetrahedral cell

• The cylindrical cell

• The spherical cell

Multiple Choice

Simple cuboidal epithelial cells line the ducts of certain human exocrine glands. Various materials are transported into or out of the cells by diffusion. (The formula for the surface area of a cube is 6 X S², and the formula for the volume of a cube is S³, where S = the length of a side of the cube.)

Which of the following cube-shaped cells would be most efficient in removing waste by diffusion?

Multiple Choice

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

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

• The egg cell, because it has the smallest surface-to-volume ratio.

• The egg cell, because it has the largest surface-to-volume ratio.

• The bacterial cell, because it has the smallest surface-to-volume ratio.

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

Multiple Choice

A student calculated the average surface area-to-volume ratio of four different types of human epithelial cells. The results are shown in the table on the left

Based on the data, which type of cell would be best suited for the lining the alveoli of the lungs, where diffusion of carbon dioxide and oxygen must occur very rapidly?

• Simple squamous cells

• Simple cuboidal cells

• Simple columnar cells

• Simple spherical cells

Multiple Choice

Two different models of a living cell are represented in the figure.

Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment?

• Cell A, because it has the larger surface-area-to-volume ratio.

• Cell A, because it has the smaller surface-area-to-volume ratio.

• Cell B, because it has the larger surface-area-to-volume ratio.

• Cell B, because it has the smaller surface-area-to-volume ratio.