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Flashcards in DIFFUSION Deck (32)
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1

Is diffusion active or passive

passive

2

What is passive transport

exchange of substances that do not require metabolic energy

3

What is active transport

exchange of substances that require metabolic energy

4

Where does passive transport get their energy from

the natural, in-built motion of particles

5

Are all particles constantly in motion and why

yes because of the kinetic energy that they possess

6

What type of motion do the particles move in

random

7

What is diffusion

the net movement of molecules or ions from a region where they are more highly concentrated to one where their concentration is lower until evenly distributed

8

Why can oxygen and carbon dioxide diffuse through simple diffusion

they are small so can pass through spaces between the phospholipids, and non-polar so they are soluble in lipids which means they can dissolve in the hydrophobic bilayer

9

What is simple diffusion

when molecules diffuse directly through a cell membrane

10

What is facilitated diffusion

the movement of charged ions and polar molecules with the help of carrier and protein channels

11

Where does facilitated diffusion get its energy from

the in-built motion (kinetic energy) of the diffusing molecules

12

What are the 2 types of protein involved in facilitated diffusion

ptorain channels and carrier proteins

13

What do protein channels form

water-filled hydrophilic channels across the membrane

14

What do protein channels allow

specific water-soluble ions to pass through the membrane

15

When do protein channels open

in the presence of specific ions

16

How do protein channels open and close

the ion binds to the protein causing it to change shape in a way that one side opens and the other closes

17

What do protein channels control

which ions enter and exit

18

What energy do carrier proteins use

the kinetic energy of the molecules

19

What do carrier proteins do

transport large molecules across the membrane down their concentration gradient

20

How do carrier proteins work

the large molecule binds to the carrier protein in the membrane at the binding site which causes the protein to change shape, and therefore releases the molecule the other side of the membrane

21

What does the rate of simple diffusion depend on (3 points)

1) concentration gradient
2) thickness of the exchange surface
3) surface area to volume ratio

22

How does concentration gradient affect simple diffusion

higher conc gradient = faster rate of diffusion

23

What is reached as simple diffusion continues

an equilibrium

24

Why happens to the rate of simple diffusion as it continues

it slows down

25

How does surface thickness affect simple diffusion

thinner = shorter diffusion distance = faste rate of diffusion

26

How does SA:V ratio affect simple diffusion

larger the SA:V ratio = faster diffusion rate

27

What is an example of an increased surface area

microvilli in epithelial cells in the small intestine

28

What does the rate of facilitated diffusion depend on (2 points)

1) concentration gradient
2) number of protein channels / carrier proteins

29

How does concentration affect facilitated diffusion

higher conc gradient = faster rate, up to a point (equilibrium reached)

30

How does the number of carrier proteins/protein channels affect rate of facilitated diffusiom

more = faster rate of facilitated diffusion