Membranes

Question 1

Water makes up roughly 60% of the body. What proportion of cellular fluid is intracellular and extracellular?

Answer 1

ICF 1/3

ECF 2/3

Question 2

Which ions are higher in presence in ICF than ECF?

Answer 2

K+

Question 3

Which ions are higher in ECF than ICF?

Answer 3

Ca 2+, Cl-, Na+

Question 4

What is osmolarity?

Answer 4

The concentration of particles in solution in osm/volume

Question 5

What is osmolality?

Answer 5

The concentration of particles in solution in osm/kg

Question 6

What is osmotic pressure?

Answer 6

The pressure that must be applied for the stopping of osmosis

Question 7

Aquaporins are always open. How is the rate of osmosis controlled?

Answer 7

Changing the number of aqua porins in the membrane

Question 8

What is tonicity? What are it’s units?

Answer 8

The comparison of osmolarity of two solutions

No units - comparative term

Question 9

Why can respiratory gases be transported by simple diffusion?

Answer 9

They are lipophillic so can pass through the phospholipid bilayer

Question 10

What is the difference between channel proteins and carrier proteins?

Answer 10

Channel proteins are passive

Most carrier proteins are active

Question 11

What do carrier proteins set up?

Answer 11

An ion concentration gradient

Question 12

What is the average resting potential inside a cell?

Answer 12

-60 mV to -70mV

Question 13

Facilitated diffusion involves what?

Answer 13

Channel/carrier proteins

Question 14

What is primary active transport?

Answer 14

Active transport with energy directly from ATP

Question 15

In primary active transport, what is an antiport?

Answer 15

A carrier which transports molecules in opposite directions

Question 16

In primary active transport, what is a uniport?

Answer 16

A protein carrier which transports a molecule in one direction

Question 17

In secondary active transport, what is a symport? Why is this secondary?

Answer 17

A protein carrier which transports two molecules in the same direction
The transport is driven by one molecule moving down its concentration gradient

Question 18

Why is active transport sometimes slower than simple diffusion?

Answer 18

Carrier proteins can be saturated

Channel proteins cannot

Question 19

What is excitability?

Answer 19

The ability to fire actiopotentials

Question 20

During an action potential, what happens to sodium and potassium ions?

Answer 20

Sodium moves into cell, potassium moves out of cell

Question 21

Cells have a negative resting potential An action potential is a wave of positivity. What type of polarisation is an action potential?

Answer 21

Depolarisation

Question 22

What is hyperpolarisation?

Answer 22

A negative shift in the resting potential of a cell

Question 23

What are voltage gated sodium channels responsible for?

Answer 23

For the upstroke of action potentials in nerve and muscle cells

Question 24

What is endocytosis?

Answer 24

Molecules move into cell via vesicles (not directly contacting bilayer)

Question 25

What is exocytosis?

Answer 25

Molecules move out of cells via vesicles, not directly contacting bilayer

Question 26

Are endocytosis and exocytosis active or passive?

Answer 26

Active

Requires ATP