1 Which of the following statements is false?

(a) CO2 and O2 can diffuse freely across the cell membranes.

(b) The differences in permeability between artificial lipid bilayers and cell membranes arise from variations in phospholipid content.

(c) Direction of passive transport of molecules across membrane is controlled by osmosis and electrochemical gradient.

(d) Cells expend energy in the form of ATP hydrolysis to maintain ion concentrations that differ from those found outside the cell.

2 Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?

(a) Na+

(b) K+

(c) Ca2+

(d) Cl–

3 Pumps are transporters that are able to harness energy provided by other components in the cells and drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________.

(a) active transport.

(b) free diffusion.

(c) positive diffusion.

(d) passive transport.

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Beverley Smith
Beverley SmithLv2
28 Sep 2019
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