Lipid Bilayer Structure
What is the main structural component of cell membranes?
Phospholipid bilayer
Do most molecules easily pass through the lipid bilayer? (yes or no)
no duh
Movement of molecules from high → low concentration is called?
Diffusion
Transport that requires no energy is called?
Passive transport
Small nonpolar molecules can cross the membrane via?
Simple diffusion
Which part of a phospholipid is hydrophilic?
head
Name two molecules that can easily diffuse through the membrane.
Oxygen (O₂) and carbon dioxide (CO₂)
Does simple diffusion require energy? (yes or no)
Nope
Transport that requires ATP is called?
Active transport
Glucose cannot freely cross the membrane because it is?
polar and large
Which part of a phospholipid is hydrophobic?
Tail
Why can ions and large molecules not pass easily?
They are polar or too large to cross the hydrophobic core duhhh
Give an example of diffusion across the membrane.
Oxygen or carbon dioxide
Give one example of passive transport.
Diffusion or osmosis
Water can pass slowly through the membrane via what process?
Osmosis
How does the bilayer form a barrier between aqueous solutions?
Hydrophobic tails prevent most molecules from passing
What is the term for a membrane’s ability to allow substances to pass?
Permeability
What drives the movement of molecules during simple diffusion?
Concentration gradient
Give one example of active transport.
Sodium-potassium pump
Membranes separate which two environments?
The aqueous inside and outside of the cell
What part of the membrane provides fluidity and helps maintain flexibility?
Cholesterol
Explain why the lipid bilayer acts as a selective barrier.
Because the hydrophobic core blocks most polar and large molecules but allows small nonpolar molecules to pass.
Predict what would happen if the concentration of O₂ outside a cell drops below the inside.
Oxygen would diffuse out of the cell until equilibrium is reached (diffusion direction reverses).
A cell uses ATP to move H⁺ ions against a gradient. Name the type of transport and why it is necessary.
Active transport; necessary to maintain concentration gradients for processes like respiration and pH balance.
free points (bc why not)
i just didnt know what to add here..