Topic 2.3: Membranes and Transport Questions

State whether facilitated diffusion uses the cell's energy (ATP), and explain your answer in one phrase.

Which type of molecule is UNABLE to cross the phospholipid bilayer directly and must instead be moved by bulk transport?

What is the basic structure of a cell membrane?

State the name of the bulk-transport process in which the plasma membrane folds inwards to bring large material into the cell.

A membrane component carries a carbohydrate chain on the outer surface and acts as an identity tag for the cell. Which component is it?

Which protein uses energy from ATP to move particles against their concentration gradient?

In simple diffusion and osmosis, which way do particles move on their own, and what does this require from the cell?

Which molecule crosses the plasma membrane most easily by simple diffusion, passing straight through the phospholipid bilayer?

On a labelled fluid mosaic diagram, which region of the membrane is hydrophilic?

A cell is placed in a solution and its mass steadily decreases over the next four minutes. State the net direction of water movement across the plasma membrane.

State the name of the membrane component that carries a carbohydrate chain on the outer surface and is responsible for cell recognition.

State the name given to a membrane protein that uses ATP to move particles against their concentration gradient.

A glucose molecule moves from a region of high glucose concentration to a region of low glucose concentration through a membrane protein. No ATP is used. What is this process?

Why must ions and large polar molecules cross a membrane by facilitated diffusion rather than passing straight through the bilayer?

In osmosis, in which direction does water move across a partially permeable membrane?

Outline why water moves by osmosis from a dilute solution into a more concentrated one across a partially permeable membrane.

Draw a labelled diagram to show how a pump protein carries out active transport across a cell membrane. Your diagram should show the direction of movement relative to the concentration gradient and the energy source.

Draw a labelled diagram of the fluid mosaic model of a cell membrane. Your diagram should show the phospholipid bilayer (with hydrophilic heads and hydrophobic tails clearly distinguished) and at least one membrane protein, a glycoprotein and cholesterol.

Outline why a selectively permeable membrane allows small, non-polar molecules to cross freely but blocks large molecules.

Cell membranes are built from a phospholipid bilayer. Explain how the amphipathic nature of phospholipid molecules allows them to form this bilayer in the watery environment of a cell.