TOPIC 2-Diffusion

Question 1

What are the two different types of diffusion?

Answer 1

-Simple
-Facilitated

Question 2

What is diffusion?

Answer 2

-The net movement of particles (molecules or ions) from an area of higher concentration to an area of lower concentration

Question 3

Which way will the net movement diffuse?

Answer 3

-To the area of lower concentration which continues until the particles are evenly distributed throughout the liquid or gas

Question 4

What is the concentration gradient?

Answer 4

-The path from an area of higher concentration to an area of lower concentration

Question 5

Is diffusion an active or passive process?

Answer 5

-Passive

Question 6

Is any energy required for diffusion?

Answer 6

-No

Question 7

Define simple diffusion

Answer 7

-When molecules diffuse directly through a cell membrane

Question 8

Give an example of simple diffusion.

Answer 8

-Oxygen and carbon dioxide can diffuse easily through cell membranes because they are small so they can pass through spaces between the phospholipids
-They are also non-polar so which makes them soluble in lipids so they can dissolve in the hydrophobic bilayer

Question 9

What are some specialised cells adapted for?

Answer 9

-Rapid transport across their membranes

Question 10

What are the 3 factors affecting the rate of diffusion?

Answer 10

-Concentration gradient
-Thickness of the exchange surface
-The surface area

Question 11

The 1___ the concentration gradient, the 2___ the rate of diffusion

Answer 11

1. Higher
2. Faster

Question 12

What happens to the difference in concentration between the two sides of the membrane?

Answer 12

-Decreases until it reaches equilibrium (the concentration on both sides is equal)
-This means that diffusion slows down over time

Question 13

The 1___the exchange surface, the 2___ the rate of diffusion

Answer 13

1. Thinner
2. Faster

Question 14

Why is the diffusion rate faster if the exchange surface is thinner?

Answer 14

-The shorter the distance the particles have to travel?

Question 15

The 1___ the surface area the 2___ the rate of diffusion

Answer 15

1. Larger
2. Faster

Question 16

Why is it faster if there is a larger SA?

Answer 16

-More space for the particles to diffuse across the membrane

Question 17

Why is the rate of diffusion faster if the concentration gradient is higher?

Answer 17

-Molecules move down the concentration gradient

Question 18

Why do larger molecules diffuse very slowly?

Answer 18

-They cannot move through the phospholipid bilayer quickly because they are too big

Question 19

Why do charged particles diffuse slowly?

Answer 19

-They are water-soluble and the centre of the bilayer is hydrophobic

Question 20

Define facillitated diffusion?

Answer 20

-Large or charged particles diffuse through carrier proteins or channel proteins in the cell membrane instead

Question 21

Is facilitated diffusion still moving down a concentration gradient and is it a passive process?

Answer 21

-Yes

Question 22

What is the function of carrier proteins?

Answer 22

-To move large molecules across the membrane down their concentration gradient
-Different carrier proteins facilitate the diffusion of different molecules

Question 23

How do carrier proteins work?

Answer 23

-First, a large molecule attaches to a carrier proteins in the membrane
-The protein changes shape
-This releases the molecule on the opposite side of the membrane

Question 24

How do channel proteins work?

Answer 24

-Form pores in the membrane for charger particles to diffuse through (down their concentration gradient)
-Different channel proteins facilitate the diffusion of different charged particles

Question 25

What are the factors affecting the rate of facilitated diffusion?

Answer 25

-Concentration gradient
-Channel or carrier proteins

Question 26

Once all the 1___ proteins are in use, facilitated diffusion cant happen any faster, even if you increase the 2___ ___

Answer 26

1. Proteins
2. Concentration gradient

Question 27

How do you calculate the rate of diffusion?

Answer 27

-Draw a tangent
-Calculate the gradient of the tangent
-Change in Y
_________________
Change in X
-Units =Ms