Which form of transport through the plasma membrane requires the expenditure of energy by the cell?

Correct Answer: C

Rationale: The term "active" implies using energy(in the form of ATP) to move a molecule against its concentration gradient, while the other processes are all passive.

Correct Answer: D

Rationale: Mitochondria produce ATP from glucose

Correct Answer: C

Rationale: The suffix "-blast" indicates that the cell is immature.

Correct Answer: C

Rationale: These ionic species are largely responsible for the membrane potential(cations are negative ions). While there is a higher concentration of Ca outside the cell than inside, there are fewer Ca than Cl ions.

Correct Answer: D

Rationale: A concentration gradient is set up by the use of energy to move Na ions to where they are in greater concentration. This requirement for energy means choice B is wrong.