HL B2.1 Membranes and membrane transport

Which type of fatty acid in a lipid bilayer increases membrane fluidity at lower temperatures?

• Saturated fatty acids

• Unsaturated fatty acids

• Trans fatty acids

• Polyunsaturated fatty acids

Saturated fatty acids in lipid bilayers:

• Have lower melting points and make membranes more fluid at high temperatures.

• Have higher melting points and make membranes stronger at higher temperatures.

• Make membranes more flexible at low temperatures.

• Lower the fluidity of membranes at all temperatures.

Which of the following organisms is likely to have more unsaturated fatty acids in its membranes?

• A desert-dwelling lizard

• A fish living in cold arctic waters

• A bird flying at high altitudes

• A tree in a tropical rainforest

What role does cholesterol play in cell membranes at higher temperatures?

• It decreases membrane fluidity.

• It prevents membranes from becoming too stiff.

• It increases membrane fluidity.

• It stabilizes membrane fluidity.

Where is cholesterol positioned in the lipid bilayer of an animal cell membrane?

• On the surface of the membrane

• Embedded between phospholipids

• Within the hydrophilic region of the bilayer

• Only in the inner leaflet of the bilayer

Cholesterol prevents membranes from stiffening at:

• High temperatures

• Low temperatures

• Both high and low temperatures

• Only in hot environments

Which process involves the fusion of vesicles with the plasma membrane to release contents outside the cell?

• Endocytosis

• Exocytosis

• Phagocytosis

• Pinocytosis

Which process allows cells to take in large particles by engulfing them in a vesicle?

• Exocytosis

• Phagocytosis

• Pinocytosis

• Facilitated diffusion

Membrane fluidity is essential for which of the following processes?

• Formation of vesicles during endocytosis

• Stability of the cell wall

• Prevention of water loss through osmosis

• Maintenance of membrane rigidity

Which of the following is an example of a neurotransmitter-gated ion channel?

• Voltage-gated sodium channel

• Nicotinic acetylcholine receptor

• Potassium leak channel

• Glucose transporter