2 - Cell membrane and transport

Question 1

How are phospholipids arranges

Answer 1

-Heads positioned on the outside as they are hydrophilic
- Tails positioned on the inside as they are hydrophobic

Question 2

What is the importance of cholesterol

Answer 2

• Restricts lateral movement of other molecules in the membrane
• More cholesterol= membrane less fluid at high temp which prevents water and dissolved ions leaking in or out - could cause dehydration or cells to burst

Question 3

Functions of the cell membrane

Answer 3

• Transport
  -Digestion
  -Immune response
  -Cell signalling

Question 4

3 factors for molecules to pass by simple diffusion

Answer 4

-Lipid soluble
-Small
-Non-polar

Question 5

What proteins does facilitated diffusion involve

Answer 5

Carrier and channel

Question 6

Active transport

Answer 6

-Against conc grad
- Involves carrier proteins and energy hydrolysis of ATP- to provide energy to attach molecule to protein and for the carrier to change shape

Question 7

Factors affecting transport

Answer 7

-Conc Grad
- Diffusion distance
-Molecule size
Temp
-Number of channel/carrier proteins
-Surface Area