Question

You observe a cell that contains fluid of that is 15% calcium. The extracellular fluid around the cell contains 5% calcium. If you observe the calcium moving through channel proteins or the outside of the cell, what mechanism are you observing?

a) Active transport
b) Osmosis
c) Passive diffusion
d) Facilitated diffusion

Answer 1

The movement of calcium through channel proteins from an area of higher concentration to a lower one is an example of facilitated diffusion.

Step-by-step explanation:

If you observe calcium moving through channel proteins from the outside of the cell where there is a higher concentration (5%) to the inside where there is a lower concentration (15%), the mechanism you are observing is facilitated diffusion. This is because facilitated diffusion involves the movement of substances from an area of higher to an area of lower concentration with the aid of carrier or channel proteins but does not require cellular energy. On the contrary, active transport would be used if the calcium was moving against its concentration gradient, which would necessitate the input of energy in the form of ATP.