Membrane Permeability AP Biology

What describes semi-permeability in a lipid bilayer?

• Allows all molecules to pass freely
• Blocks certain molecules based on size and chemical nature
• Selectively permits molecules based on DNA
• Completely impermeable to all substances

What property of the lipid bilayer core makes it hydrophobic?

• Presence of hydrophilic heads
• Hydrophobic tails of phospholipids
• Embedded proteins
• High cholesterol content

What type of molecules can easily pass through the lipid bilayer?

• Charged molecules
• Large polar molecules
• Small nonpolar molecules
• Ions

What increases the permeability of a lipid bilayer?

• More saturated fatty acid tails
• Low temperature
• More unsaturated fatty acid tails
• Presence of cell walls

How do higher temperatures affect membrane permeability?

• Makes the membrane less permeable
• Decreases fluidity
• Increases permeability
• Causes membrane rupture

What additional feature makes cell membranes selectively permeable?

• Embedded proteins
• Cholesterol
• Hydrophobic core
• Presence of cell walls

What function does cholesterol serve in the membrane?

• Reduces membrane permeability
• Allows selective transport of ions
• Increases membrane fluidity
• Blocks all molecules

What best describes the fluid mosaic model?

• Only phospholipids in the membrane
• Phospholipids and proteins creating selective permeability
• A rigid structure blocking all substances
• A uniform lipid layer

Why do cells need selectively permeable membranes?

• To block all molecules
• To create livable cellular conditions
• To prevent osmosis
• To export organelles

Tags

NGSS.MS-LS1-2

What is osmosis?

• Diffusion of solutes across a membrane
• Movement of water through a semi-permeable membrane
• Active transport of ions
• Protein-mediated glucose uptake