2.5 Cell Membranes

Question 1

Phospholipid role

Answer 1

Forms bilayer

Barrier to hydrophilic substances (charged ions/molecules)

Question 2

Cholesterol

Answer 2

Stabilises membrane and makes it less permeable

Can also maintain fluidity at low temperatures

Question 3

Glycoproteins

Answer 3

Receptor site
Allow hormones to bind with them
Response in cell

Or recognition site for other cells

Question 4

Channel proteins

Answer 4

Hydrophilic substances can pass through

Open and close

Question 5

Carrier proteins

Answer 5

Transporters

Substances move up concentration gradient

Question 6

Glycolipids

Answer 6

Provide energy

Markers for cellular recognition

Question 7

Heating a membrane makes it

Answer 7

More fluid and more permeable

Question 8

Low temperatures on membranes

Answer 8

Decreases permeability
Carrier proteins may not work as ATP is hard to produce at low temperatures
Molecules and ions have less KE

Question 9

Types of signal

Answer 9

Chemical - hormone

Electrical - nervous impulse

Question 10

3 ways of cell signalling

Answer 10

Hormone attaches to receptor, brings about response
Receptor interacts with G-protein, activates enzyme
Receptor also is an enzyme, signal activates it

Question 11

Single membranes organelle

Answer 11

Vesicle
ER
Golgi
Vacuole

Question 12

Double membranes organelles

Answer 12

Nucleus
Chloroplasts
Mitochondria

Question 13

No membraned organelles in eukaryotes

Answer 13

Ribosome

Cilia and flagella