Membrane Permeability

What does selective permeability mean?

Why is the phospholipid bilayer a barrier?

What part of the phospholipid is hydrophilic?

What part of the phospholipid is hydrophobic?

Which substances usually need a membrane protein to cross?

Which substances can cross more easily without a protein?

Why does glucose need a transporter?

Why do Na+ and K+ need channels or transporters?

What is a membrane transport protein?

What is the difference between a channel and a carrier?