Transport/Membranes

Question 1

Phospholipids

Answer 1

2 fatty acids/glycerol/phosphate

-hydrophobic tail & hydrophilic head-so form bilayer.

Question 2

Lipid

Answer 2

Soluble molecules, water and other small substances can diffuse through. Water soluble ones & larger molecules (e.g. glucose) can’t.

Question 3

Fluid-mosaic model

Answer 3

Fluid -Molecules are moving

Mosaic -made up of proteins and phospholipids

Question 4

Diffusion

Answer 4

Diffusion = net movement of particles from an area of high to low concentration. Passive process, down conc gradient.

Question 5

Diffusion is quicker with

Answer 5

-bigger SA/short diffusion path/higher temp/bigger concentration gradient
Higher temp gives particles more kinetic energy, so move faster.

Question 6

Facilitated diffusion

Answer 6

When molecule (e.g. glucose) is too large to diffuse across membrane can go via protein channels/carriers. V. similar to diffusion, (e.g. passive etc), but involves proteins that are specific to the substance crossing.

Question 7

Carrier proteins

Answer 7

Carrier proteins may become the limiting factor in fac. diffusion. Become fully saturated with molecules (can’t carry any more across membrane)

Question 8

Osmosis

Answer 8

Net movement of water particles from an area of high concentration to low, across a partially permeable membrane. Passive/no carrier proteins/down gradient.

Question 9

Cell membrane

Answer 9

Partially permeable. Contain a phospholipid bilayer, intrinsic proteins (span membrane), extrinsic proteins (on surface), cholesterol (stability) & glycolipids (recognition site)