2.5 diffusion Flashcards Preview

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Flashcards in 2.5 diffusion Deck (23):
1

What are all cells surrounded by?

Partially permeable membranes

2

What do partially permeable membranes do?

Control material entry and exit

3

Why do all cells need to import substances?

To survive and export waste materials

4

What are the three processes by which substances move across membranes?

Diffusion
Osmosis
Active transport

5

What can movement across membranes be?

Passive or active

6

What does all movement require?

Energy

7

Where does passive movement utilise its energy from?

The natural movement of particles

8

is diffusion passive or active?

Passive

9

Define diffusion:

The passive movement of molecules down a concentration gradient, from an area of high concentration to an area of low concentration across a membrane until there is no more net movement and equilibrium had been reached

10

Give an example of diffusion in the body:

Respiration occurs at gaseous exchange surfaces, oxygen diffuses from the capillaries to the alveoli

11

What sort of molecules diffuse quickly through the phospholipids?

Small Jon polar molecules such as oxygen and carbon dioxide

12

What is fick's law?

Rate of diffusion is proportional to = (surface area x difference in concentration) ÷ length if diffusion path

13

The shorter the diffusion pathway...

... The faster diffusion happens

14

What is the length of diffusion path?

Membrane thickness

15

What affect will increasing the surface area across which particles diffuse have?

Increase in rate of diffusion

16

What effect will increasing the size of the concentration gradient have?

Increase the rate of diffusion

17

What effect will increasing the distance over which diffusion takes place have?

Decrease rate of diffusion

18

Why does respiration occur quickly?

Because alveoli and capillarity are one cell thick so oxygen is able to quickly diffuse

19

What factors affect the rate of diffusion?

Temperature
Concentration difference
Thickness of exchange surface
Surface area
Nature of plasma membrane
Size and nature of diffusing molecule

20

What effect does increasing temperature have on the rate of diffusion?

The higher the temperature the faster the rate of diffusion as molecules have more kinetic energy so they move faster

21

The greater the concentration difference between the two areas...

The faster the rate of diffusion

22

The thinner the exchange surface...

The faster the rate of diffusion as the shorter the distance particles have to travel

23

The larger the surface area of the membrane...

The faster the rate of diffusion

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