Diffusion

Question 1

What is diffusion?

Answer 1

The intermingling of substances by natural movement of their particles

Question 2

What 3 things can speed up diffusion?

Answer 2

Temperature
Give them space
Kinetic energy

Question 3

Ammonia vapour through a tube experiment

What is the method?

Answer 3

1. Place Cotten wool in a tube and close the tube using rubber bungs
2. Set timer immediately
3. After 5 seconds record the length on the tube where the red litmus paper has turned blue
4. Repeat every 5 seconds until it stops

Question 4

Ammonia vapour through a tube experiment

When the ammonia vapour if given off the alkaline can be detected by what?

Answer 4

Using red litmus paper that turned blue when ammonia reaches it

Question 5

Ammonia vapour through a tube experiment

What is the independent variable?

Answer 5

Time

Question 6

Ammonia vapour through a tube experiment

What is the dependent variable?

Answer 6

Distance etc…

Question 7

Ammonia vapour through a tube experiment

What sort of graph should be drawn and why?

Answer 7

Line graph

Because the independent and dependent variable are both numbers

Question 8

Ammonia vapour through a tube experiment

Describe the results on the graph, what do you notice happening?

Answer 8

Between 5s and 20s it has diffused 14mm. After first diffusing it slowed down, between 30s and 40s it was only diffusing 5mm

Question 9

Ammonia vapour through a tube experiment

Explain the results of this experiment

Answer 9

At the beginning there was a high concentration gradient so diffusion took place quickly.
Towards the end of the experiment the concentration gradient was low, so diffusion took place slowly

Question 10

Does diffusion use up energy?

Answer 10

No

Question 11

Name 3 examples of diffusion in living organisms

Answer 11

1. Carbon dioxide diffuses from the blood circulating around the lungs
2. Oxygen diffuses from blood cells in the blood streams into muscles
3. In pregnancy food/Oxygen diffuses into baby via placenta

Question 12

Describe how a red blood cell has adapted to make diffusion quicker and faster?

Answer 12

Larger surface area

Concave to be faster

Question 13

Phenolphthalein pink agar experiment

What’s the aim of the experiment?

Answer 13

Carry out an investigation into how the surface area to volume ratio of agar blocks effect the rate of diffusion

Question 14

Phenolphthalein pink agar experiment

What’s your hypothesis for this experiment?

Answer 14

The bigger the square the longer it will take to diffuse

Question 15

Phenolphthalein pink agar experiment

Evaluation for this experiment

Answer 15

The phenolphthalein agar cubes volume increased it takes longer to diffuse, because of the volume: surface area ratio

Question 16

Phenolphthalein pink agar experiment

Is there any possible errors in this experiment?

Answer 16

The cubes won’t be cut exactly

Question 17

Why is diffusion important?

Answer 17

It is the main way in which living organisms obtain the things they need and get rid of their waste products.

Question 18

Most single celled animals are less than 1mm across and the largest are only about 2mm long. Explain this?

Answer 18

It requires oxygen for diffusion, if it is to big it can’t get the oxygen because all compared to the volume ratio

Question 19

What is osmosis?

Answer 19

Osmosis is the next movement of the water from a high water concentration to a low water concentration a perticually permeable membrane

Question 20

What state does osmosis take place?

Answer 20

Water

Question 21

Explain the results in a osmometer?

Answer 21

Water particles come in, but the sugar is to tick to come out. Liquids rises up the tube

Question 22

What will happen to red blood cells if they are placed in a solution of distilled water?
(Animal cells)

Answer 22

There would be too much water so it would pop

Question 23

Explain why an animal cell would pop?

Answer 23

1. Net diffusion of water into cell, so cell swells and bursts
2. No net diffusion of water, so cell is normal size
3. Net diffusion of water out of cell, so the cell shrinks

Question 24

Plant cells do not burst in placed on distilled water, why?

Plant cells

Answer 24

The cell wall will stop to much water from entering so it won’t pop

Question 25

Explain why a plant cell will not pop

Answer 25

1. Net diffusion of water into cell, so cell becomes turgid
2. No net diffusion of water, so cell is normal size
3. Net diffusion of cell water so cytoplasm shrinks from cell wall and plasmolyses

Question 26

What does passive mean?

Answer 26

It doesn’t require a lot of energy

Question 27

What does active transport mean?

Answer 27

It is the movement of a substance from a low to high concentration across a cell membrane. This process requires energy released by respiration

Question 28

Give two main differences between diffusion and active transport?

Answer 28

1. Active transport is the movement against a concentration gradient
2. Active transport requires energy from respiration

Question 29

Why do you cells that carry a load of active transport have a lot of mitochondria?

Answer 29

Mitochondria a is where most of respiration takes place so the more mitochondria you have the more active transport there is.

Question 30

Where does the energy for active transport come from?

Answer 30

Respiration is were the energy comes from