Question

which of the following scenarios describes movement of materials from an area of low concentration to an area of high concentration across a cell membrane? oxygen moving from the lungs into the blood. water moving into a cell placed in a hypotonic solution. sodium ions being pumped out of a nerve cell. glucose entering a cell via facilitated diffusion when its concentration is higher outside. passive transport across the cell membrane requires: the movement of substances down their concentration gradient. the assistance of carrier proteins only. movement of substances against their concentration gradient. energy in the form of atp.

Explanation:

For the first question, active transport moves substances against the concentration gradient (from low to high concentration). Sodium - ion pumping out of a nerve cell is an example of active transport. For the second question, passive transport involves the movement of substances down their concentration gradient without the use of energy.

Answer:

First question: Sodium ions being pumped out of a nerve cell.
Second question: The movement of substances down their concentration gradient.