Question

Biology A Semester Online Practice
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Question
A scientist is studying a new protist species that is a type of single-celled eukaryote. Using both microscope and biochemical techniques, they have determined the following movements across the cells membrane:

Biomolecule Movement #1:

Lactose moves through a channel protein in the membrane of the cell from a high concentration on the outside to a low concentration of lactose on the inside.

Biomolecule Movement #2:

Potassium is pumped out of the cell using a membrane protein from a low concentration of potassium on the inside of the cell to a high concentration of potassium on the outside of the cell.

Biomolecule Movement #3:

Oxygen gas moves from a high concentration on the outside of the cell to a low concentration inside the cell. The gas does not appear to need any membrane protein to cross the cell membrane.

Biomolecule Movement #4:

Water moves from a hypotonic environment on the outside of the cell to a hypertonic environment on the inside of the cell through protein channels called aquaporins.



Based on these conclusions, identify the movement of biomolecules that demonstrates both osmosis and facilitated diffusion across a cell membrane.

(1 point)
Responses

Biomolecule Movement #4
Biomolecule Movement #4 - no response given

Biomolecule Movement #3
Biomolecule Movement #3 - no response given

Biomolecule Movement #2
Biomolecule Movement #2 - no response given

Biomolecule Movement #1

Answer 1

Biomolecule Movement #4

Explanation: Water moving through aquaporin channels down its concentration gradient is osmosis (water diffusion) and is facilitated by membrane proteins (aquaporins), so it is both osmosis and facilitated diffusion.