Practise IB Biology HL B2.1 with membrane diagrams and data questions covering selective permeability, transport mechanisms, fluidity, vesicles and ion pumps.
Outline how the amphipathic properties of phospholipids play a role in membrane structure.
i
a part hydrophobic/not attracted to water/non-polar AND part hydrophilic/attracted to water/polar;
b bilayer formed (formed naturally by phospholipids in water);
c hydrophilic heads/parts face outwards and hydrophobic tails/parts face inwards;
Marking guidance:
Do not allow water loving/hating in mpa or mpc
2 max
State the role of cholesterol in animal cell membranes.
ii
a controls/regulates/reduces fluidity of membrane/ prevents crystallization of phospholipids;
b reduces permeability to some substances;
Marking guidance:
Do not accept 'stabilizes membrane'
1 max
Neural pathways in living brains can now be mapped by tracking the movement of water molecules inside axons. What keeps water molecules inside axons?
Plasma membrane
Hydrogen bonding
Pump proteins
Synapse
A
Which process results in the exchange of gases across the membrane of pneumocytes?
Active transport
Simple diffusion
Facilitated diffusion
Mass flow
B