Question

traveling molecules
for the following scenarios, determine whether the molecules in the scenario are moving by (s) simple
diffusion, (f) facilitated diffusion, or (a) active transport.

1. ______ for water to travel across the cell membrane at a substantial rate, the water molecules travel through protein channe

known as aquaporins.

1. ______ while water molecules are polar, they are also very small. one fact not mentioned in the video is that some water

molecules are able to squeeze directly through the phospholipid bilayer due to their small size.

1. ______ charged ions are traveling through a cell membrane with the concentration gradient.
2. ______ cells lining the gut need to take in glucose, but at a certain time, the concentration of extracellular glucose is lower tha

the concentration already stored in the cells.

1. ______ at a certain time, glucose is in a high concentration outside of a cell and needs to travel through the membrane into th

cell.

Explanation:

Question 8

Step1: Recall transport types

Simple diffusion (S): no protein, down gradient. Facilitated (F): protein, down gradient. Active (A): protein, up gradient.

Step2: Analyze scenario 8

Water uses aquaporins (protein channels), down gradient (substantial rate implies help, but still down? Wait, aquaporins are for facilitated diffusion of water. So uses protein, down gradient. So F.

Step1: Recall transport types

Simple diffusion: no protein, small/nonpolar, down gradient.

Step2: Analyze scenario 9

Water squeezes through phospholipid bilayer (no protein), small size. So simple diffusion (S).

Step1: Recall transport types

Charged ions: can't pass bilayer easily. Facilitated (F) uses protein, down gradient. Active (A) is up.

Step2: Analyze scenario 10

Charged ions, with concentration gradient (down), so needs protein (facilitated diffusion, F).

Answer:

F

Question 9