Cell membrane and transport

Which molecule is the basis of all biological membranes?

• Protein

• Cholesterol

• Phospholipid

• Mitochondria

Phospholipid molecules have a 'head' region that contains a phosphate group and a 'tail' region composed of two hydrocarbon chains. Which term correctly describes the properties of the phosphate head?

• Hydrophillic

• Agoraphobic

• Hydrophobic

• Amphipathic

Why do phospholipids form bilayers in water?

• Due to their amphipathic properties.

• Due to their hydrophilic properties.

• Due to their hydrophobic properties.

• Due to their agoraphobic properties.

Which molecules can not cross the phospholipid bilayer by diffusion?

• small, polar molecules (e.g. water, ethanol)

• large, polar molecules (e.g. glucose)

• hydrophobic molecules (e.g. benzene)

• small, non-polar (carbon dioxide, oxygen)

Diffusion is...

• when a substance is present in equal concentrations on both sides of a membrane

• the movement of a substance from an area of low concentration to an area of high concentration

• the movement of a substance from an area of high concentration to an area of low concentration

• the speed at which molecules move across a biological membrane

Select the correct description of the location of a peripheral protein within a plasma membrane.

• embedded in the hydrophobic layers of the plasma phospholipid bilayer

• attached to one surface of the phospholipid bilayer

Which of the following are possible functions of membrane proteins?

• communication

• adhesion

• transport

• receptor

Which method of cell membrane transport requires energy?

• Facilitated diffusion

• Active transport

• Simple diffusion

During active transport, a substance is moved

• From high to low concentration by a carrier protein

• From low to high concentration by a carrier protein

• From high to low concentration through the phospholipid bilayer

• From low to high concentration through the phospholipid bilayer

What determines the selectivity of a plasma membrane?

• The phospholipid bilayer

• The proteins present in the phospholipid bilayer

• The solutions present on either side of the membrane

• The temperature