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Oxygen diffuses into a cell because the concentration of oxygen outside the cell

ID: 1562490 • Letter: O

Question

Oxygen diffuses into a cell because the concentration of oxygen outside the cell is larger than the concentration inside the cell.

If the diameter of the cell is doubled (but the concentration of O2 inside the cell and the thickness of its membrane remains the same), what happens to the rate at which oxygen enters the cell?

A. It doubles
B. It is reduced to half of its value for the smaller cell
C. It increases by a factor of 4
D. It is reduced to one-quarter of the value for the smaller cell
E. It remains the same

Explanation / Answer

we know that rate at which oxygen enters the cell dn/dt = P*A*dc/dx

where A is the membrane area and P is the permeability constant. P is a constant relating the ease of entry of a molecule into the cell depending on the molecule's size and lipid solubility.

this implies rate is directly proportional to area (r^2)

given diameter is doubled implies radius is also doubled

new rate = 4r^2

this implies increased by a factor of 4 times