membranes🧍‍♂️

Question 1

describe structure of plasma membrane

Answer 1

• phospholipid bilayer containing proteins
• cholesterol molecules beyween phospholipids
• glycoproteins sticking out
• extrinsic and intrinsic proteins

Question 2

if cells dont take up any ammonia what can you conclude about their plasma membrane

Answer 2

-not permeable to ammonia

Question 3

where is cholesterol

Answer 3

between phospholipids

Question 4

where are glycoproteins

Answer 4

on surface

Question 5

why does freezing tissue make its enzymes react more

Answer 5

• freezing damages plasma membrane

- increases permeability of membrane to enzyme

Question 6

how do plasma membranes contribute to cell signalling

Answer 6

• release of signal molecule by exocytosis
• glycoproteins are receptors
• receptor is specific
• receptor and signal molecule are complementary
• attachment of signal molecule to receptor triggers response

Question 7

roles of membranes inside cells

Answer 7

• compartmentalisation
• isolation of metabolic pathways
• create concentration gradients
• control what enters and leaves organelles
• site for enzyme attachment

Question 8

how do proteins on surface of vesicles ensure substance gets to target organelle

Answer 8

• protein has specific shape
• receptor on organelle is complementary to protein
• receptor only found on target organelle

Question 9

what is active transport

Answer 9

• movement of substance against concentration gradient
• uses atp
• using carrier protein

Question 10

examples of active transport

Answer 10

• hydrogen ions out of companion cells
• sucrose out of sieve tube at sink
• mineral ions into root hair cell

Question 11

ethanol effect on osmosis

Answer 11

• ethanol dissolves phospholipid bilayer

- osmosis cannot occur

Question 12

suggest why low pH makes pigment leak out of beetroot cells

Answer 12

• denatures membrane proteins

- membrane permeability increased