Keywords - transport across membranes

Question 1

Phospholipid bilayer

Answer 1

Double layer of phospholipids that forms majority of bio. membranes. Arranges w/ hydrophobic tails inwards + phosphate heads outside

Question 2

Fluid-mosaic model

Answer 2

Arrangement of various molecules (eg. cholesterol, protein, phospholipid bilayer) to form bio. membrane. Has flexible structure as phospholipids can move within membrane

Question 3

Cholesterol

Answer 3

Lipid that adds strength + rigidity by pulling phospholipids together to limit movement

Question 4

Simple diffusion

Answer 4

Net movement of molecules/ions from high to low conc until equilibrium reached. Can occur across membrane through bilayer

Question 5

Facilitated diffusion

Answer 5

Net movement of molecules/ions across membrane via protein channel or carrier proteins, from high to low conc until equilibrium is reached

Question 6

Water potential

Answer 6

Pressure created by water molecules (KPa) - extent to which water can move from one solution to another. More water molecules in given volume, the higher the water potential. Highest value is 0 = pure water

Question 7

Osmosis

Answer 7

Movement of water from high w.pot to low w.pot across partially permeable membrane until equilibrium is reached

Question 8

Active transport

Answer 8

Movement of substance from low to high conc using energy (ATP) and a carrier protein

Question 9

Co-transport

Answer 9

Transport of one substance coupled with another substance across plasma membrane in same direction using carrier protein (symporter protein)

Question 10

Microvilli

Answer 10

Tiny finger like projections of membrane + cytoplasm from cell surface. Greatly increase surface area to increase rate of exchange