Biological Membranes

Question 1

Osmosis

Answer 1

Movement of water molecules from a region of high wp - low wp across a partially permeable membrane
-water potential of pure water=0

Question 2

Diffusion

Answer 2

Movement of particles from high conc to low conc
Equilibrium= no net movement
stable system, can be dynamic
-temp, kinetic energy affect rate

Question 3

Active transport

Answer 3

Moving against the conc gradient
low - high bulk transport
-needs energy from ATP
Requires carrier proteins
membrane bound vesicle containing substances moves to cell surface
-membrane and vesicle fuse (releasing contents)

Question 4

Cell membranes

Answer 4

Partially permeable barriers, some substances dissolved in lipid layer
Roles
-regulates transport of materials
-has antigens (cell signalling)
-separates cell contents from cytoplasm

Question 5

Transport proteins

Answer 5

Channel- Pores allow water soluble molecules or ions through eg calcium ions
Carrier-specific molecule fits into carrier(shaped), large hydrophilic glucose

Question 6

Fluid mosaic model

Answer 6

Phospholipid bi layer 
hydrophilic heads 
Hydrophobic tails
5-10nm thick 
Cholesterol (keep ridgid)
Proteins
Carbohydrates

Question 7

Beetroot

Answer 7

beetroot in samples of water

• increased temp=more kinetic energy
• phospholipids move faster in membrane
• membrane becomes ‘leaky’ -red pigment leaks