D) move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle
The membranes of winter wheat are able to remain fluid when it is extremely cold by __.
A) increasing the percentage of unsaturated phospholipids in the membrane
The force driving simple diffusion is ___, while the energy source for active transport is __.
A) the concentration gradient; ATP
The voltage across a membrane is called the __.
B) membrane potential
According to the fluid mosaic model of cell membranes phospholipids ___.
C) can move laterally along the plane of the membrane
For a protein to be an integral membrane protein, it would have to be __.
B) aphipathic, with at least one hydrophobic region
Which of the following most accurately describes selective permeability?
C) Only certain molecules can cross a cell membrane
Ions diffuse across membranes through specific ion channels down __.
C) their electrochemical gradients
Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean?
B) Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life
Lysosomes maintain a pH of approximately 4.5-4.7, which is more acidic than the cytosol of the cell. Which of these is most likely responsible for maintaining the low pH of lysosomes?