B2.1 HL Membrane Transport

What characteristic of unsaturated fatty acids affects membrane fluidity?

• Higher melting points

• Ability to pack closely together

• Lower melting points

• Single bonds between carbon atoms

Membrane fluidity is crucial for which of the following reasons?

• Ensuring that proteins can move and function correctly

• Making the membrane impermeable

• Solidifying the membrane

• Preventing any movement within the membrane

The lake sturgeon adjusts its cell membrane fatty acid composition to:

• Migrate to warmer regions

• Increase its size

• Survive in cold conditions

• Attract mates

Tags

NGSS.HS-LS1-3

NGSS.HS-LS4-4

Homeoviscous adaptation refers to:

• The stiffening of the membrane at low temperatures

• Increasing saturated fatty acids as the temperature rises

• Adapting the lipid composition to maintain membrane fluidity

• The decrease in cholesterol in the membrane

Cholesterol in animal plasma membranes serves to:

• Decrease membrane flexibility

• Stabilize membrane structure at varied temperatures

• Remove the need for phospholipids

• Make the membrane completely rigid

At lower temperatures, cholesterol:

• Increases permeability to solutes

• Forces phospholipids closer together

• Maintains membrane fluidity by keeping phospholipids apart

• Makes the membrane solidify

The polar part of the cholesterol molecule is attracted to:

• The fatty acid tails of the phospholipids

• The phosphate heads of the phospholipids

• The exterior environment of the cell

• The cytoplasm

Bulk transport across the plasma membrane includes:

• Simple diffusion

• Facilitated diffusion

• Cytosis

• Osmosis

Endocytosis is defined as:

• The plasma membrane pinching outward

• Material being exported out of the cell

• The plasma membrane pinching inward

• Vesicles disintegrating within the cell

Which process describes the uptake of solid particles by cells?

• Exocytosis

• Endocytosis

• Phagocytosis

• Pinocytosis