3.2 Concept of Movement of Substances Across a Plasma Membrane

Question 1

Characteristics of substances across the plasma membrane:

1. Nonpolar molecules
2. Small molecule & ion
3. Large molecule

Answer 1

1. • fatty acid
   • glycerol
   • fat soluble vitamins (A, D, E, K)
2. • polar molecules: water
   • nonpolar molecules (o2, co2)
   • ion (K+, Na+, Ca2+, Mg2+)
3. • glucose
   • amino acid

Question 2

Passive Transport

Answer 2

=> does not require energy

1. Simple diffusion
2. Osmosis
3. Facilitated diffusion

Question 3

Simple diffusion

Answer 3

• movement of molecules or ions
• from high concentration area to a lower concentration area
  (follow concentration gradient)
• down the concentration gradient until a dynamic equilibrium is achieved
• fatty acid, glycerol, o2, co2

Question 4

Osmosis

Answer 4

• from a higher water potential to a low water potential
• occurs through the phospholipid bilayer
• ONLY water, h2o

Question 5

Facilitated diffusion

Answer 5

• through transport proteins
  (carrier proteins, channel protein)

-