Tushar 1.4

Question 1

What is passive transport

Answer 1

high to low conc
No ATP
includes:
 - diffusion
 - facilitated diffusion
- osmosis
relies on kinetic energy

Question 2

What is simple diffusion

Answer 2

passive net movement of particles from high concentration to low concentration
Small + non-polar things w no charge diffuse easily across membrane

Question 3

What is facilitated diffusion

Answer 3

Passive movement from high to low concentration across cell membrane via the aid of a membrane protein
For large polar substances/ions
Membrane protein is specific

Question 4

2 types of transport facilitated diffusion proteins

Answer 4

Channel

Carrier

Question 5

Carrier and channel proteins

Answer 5

Carrier proteins

• change shape
• specific
• also does active transport
• slower

Channel proteins

• have pore for ions to cross (no change shape)
• selective
• cant do active transport
• faster

Question 6

What is osmosis

Answer 6

net movement of water particles across a semi-permeable membrane from a region of low solute conc (high water potential) to a region of high solute conc (low water potential) till equilibrium

Question 7

Which molecules don’t affect osmolarity

Answer 7

insoluble

Question 8

What is osmolarity

Answer 8

measure of solute concentration

Question 9

hypertonic, hypotonic, isotonic

Answer 9

hypertonic: relatively higher osmolarity
hypotonic: relatively lower osmolarity
isotonic: solutions w same osmolarity

Question 10

What is active transport

Answer 10

Movement of substances against conc gradient
Uses ATP
Needs protein pumps that change shape

Question 11

Sodium-potassium pump

Answer 11

1) 3 sodium ions bind to binding site of pump
2) phosphate group transferred to pump via hydrolysis of ATP
3) this causes protein pump to change shape, moving 3 sodium ions out of cell
4) Now 2 potassium ions on the extracellular side bind to the pump
5) phosphate group is released, pump returns to original shape
6) Change in shape moves potassium ions into the cell

Question 12

endocytosis and exocytosis

Answer 12

• needs energy
• cell membrane can break and reform, it is fluid and flexible
• for larger molecules

Question 13

endocytosis

Answer 13

• for large to enter the cell
• Cell membrane moves inwards to surround the molecule
• molecule is sealed in a vesicle
• vesicle moves into the cell
• phagocytosis: uptake of solid substances
• pinocytosis: uptake of fluids

Question 14

Exocytosis

Answer 14

• for large substances to exit cell
• vesicle fuse with membrane, expelling contents extracellular environment
• this replaces phospholipids lost by endocytosis