AP Biology Chapter 7: Cell Membrane Structure and Function

What type of molecule are phospholipids?

• hydrophilic

• amphipathic

• hydrophobic

• ions

As per the Fluid Mosaic Model for the Plasma Membrane, how are proteins organized and move?

• They are organized randomly and all proteins are stagnant in their fixed positions

• They are organized randomly and all proteins can drift through the membrane

• They are organized in groups and some drift through the plasma membrane

• They are organized in groups and no proteins can move from their fixed locations

What molecule acts as a buffer that restrains lipid movement to maintain the fluidity of the lipid bilayer?

• Receptor proteins

• No molecule fulfills this role

• Glycoproteins

• Cholesterol

What is the difference between integral and peripheral proteins?

• Integral proteins are imbedded in the membrane whereas peripheral proteins are merely appendages attached to the membrane.

• They are the same but with different names depending on the cell type

• Peripheral proteins are imbedded in the membrane whereas Integral proteins are merely appendages attached to the membrane.

• One is completely hydrophobic whereas the other is completely hyrophilic

True or False: Proteins involved in Cell-Cell Recognition help with the formation of specialized tissues and organs in an organism

• True

• False

True or False: Transport proteins help hydrophobic substances pass through the membrane

• True

• False

If substance A and substance B are diffusing down their concentration gradients, how will they react to each other?

• They will diffuse so there all of one substance on one side and the other substance on the other side

• They will diffuse down their gradients regardless of the activity of the other substance

• They will prevent each other's diffusion across the membrane

How will an animal cell react when submerged in a hypertonic environment?

• It will lose water and shrivel

• It will remain the same

• It will gain water and possibly lyse

• Its plasma membrane will separate from its cell wall and plasmolyze

What determines the diffusion of ions?

• Chemical factors

• Electrical Factors

• Je ne sais pas francais.

• Chemical factors (ion gradient) and Electrical factors (membrane potential)

If a sucrose molecule binds to a sucrose-H+ cotransporter but a hydrogen ion does not bind to the cotransporter, will sucrose be able to be transported across the membrane?

• No, a hydrogen ion is needed for the cotransporter to transport sucrose against its gradient and into the cell

• No, you need two sucroses for the sucrose molecule to be transported

• Yes, only a sucrose molecule is needed