Diffusion

Question 1

diffusion

Answer 1

the net movement of particles from an area of higher concentration to an area of lower concentration

Question 2

does diffusion require energy

Answer 2

no

Question 3

is diffuison a passive or active process

Answer 3

passive

Question 4

what are the 2 requirements for substances to be able to pass directly across cell membranes (undergo simple diffusion)

Answer 4

• small

-non-polar

Question 5

why does being small mean substances can diffuse via simple diffusion

Answer 5

it means they can pass through the spaces in phospholipids

Question 6

why can non-polar cross the membrane via simple diffusion

Answer 6

they can dissolve in the hydrophobic core of the cell membrane

Question 8

by what process do large or polar molecules diffuse

Answer 8

facilitated diffusion

Question 9

which 2 types of proteins help to accommodate facilitated diffusion

Answer 9

carrier proteins

channel proteins

Question 10

do carrier or channel proteins just allow any substance to pass through?

Answer 10

no they are very specific and only allow 1 or 2 types of molecule to pass through

Question 11

what do carrier proteins mostly transport

Answer 11

large molecules

Question 12

how do molecules diffuse via carrier proteins

Answer 12

a large molecule attaches to a carrier protein

this therefore causes the carrier protein to change shape

the carrier protein then releases the molecule on the opposite side of the membrane

Question 13

what molecules do channel proetins mainly transport

Answer 13

ions

Question 14

how do substances travel through channel proteins

Answer 14

proteins form pores in the cells membrane which ions can travel through

Question 15

which are the 5 factors that affect the rate of diffusion

Answer 15

1. temperature
2. concentration gradient
3. thickness of membrane
4. surface area
5. number of carrier/ channel proteins

Question 16

how does temperature affect the rate of diffusion

Answer 16

at higher temperatures, particles have more kinectic energy and therefore move faster

Question 17

how does concentration gradient affect rate of diffusion

Answer 17

the steeper the concentration gradient, the faster the rate of diffusion

Question 18

how does thickness of membrane affect rate of diffusion

Answer 18

the particles have to travel shorter distances through thin exchange surfaces and therefore can diffuse more quickly

Question 19

how does surface area affect rate of diffusion

Answer 19

the larger the surface area, the more particles can cross the membrane at once, increasing the speed of diffusion

Question 20

how does the number of carrier or channel proteins affect the rate of diffusion

Answer 20

the more of these proteins, the faster the rate of facilitated diffusion