Diffusion, Osmosis And Active Transport

Question 1

Define diffusion

Answer 1

The net movement of molecules or ions from a region where they are highly concentrated to one where their concentration is lower

Question 2

What 3 factors affect diffusion

Answer 2

Concentration gradient
Area over which the diffusion takes place
Thickness of exchange surfaces

Question 3

How does the concentration gradient affect the rate of diffusion

Answer 3

The greater the difference in concentration of molecules/ions on either side of the exchange surface, the faster the rate of diffusion

Question 4

How does the type of area that diffusion takes place in affect the rate of diffusion

Answer 4

The larger the area of the exchange surface, the faster the rate of diffusion

Question 5

How does the thickness of the exchange surface affect the rate of diffusion

Answer 5

The thinner the surface, the faster the rate of diffusion

Question 6

How does the type of molecule affect diffusion

Answer 6

The size and nature of the diffusing molecule affects diffusion

Question 7

Are smaller molecules or larger molecules faster

Answer 7

Smaller

Question 8

Are water soluble molecules or lipid soluble molecules faster

Answer 8

Lipid soluble

Question 9

Are polar molecules or non polar molecules faster

Answer 9

Non polar

Question 10

What can’t ions do

Answer 10

Pass through/diffuse across a membrane

Question 11

What does facilitated diffusion require

Answer 11

A protein molecule

Question 12

Where does protein molecules for facilitated diffusion come from

Answer 12

The cell membrane

Question 13

What are the 2 types of protein molecule

Answer 13

Channel protein or carrier protein

Question 14

What are channels? What does this allow?

Answer 14

Channels are hydrophilic
They allow water soluble ions and molecules (eg glucose) to pass through

Question 15

What is movement in facilitated diffusion? What does that mean

Answer 15

Passive
This means it doesn’t use energy

Question 16

How selective is facilitated diffusion

Answer 16

Very
It only allows 1 kind of molecule to go through which has to be complementary to the protein

Question 17

When does net movement occur in facilitated diffusion

Answer 17

When there is a difference in concentration

Question 18

What is osmosis

Answer 18

The passage of water from a region of high water potential to a region of low water potential across a partially permeable membrane

Question 19

What is the unit for water potential

Answer 19

Psi ψ

Question 20

What is the water potential of pure water

Answer 20

Zero

Question 21

What does adding a solute to pure water do?

Answer 21

Lowers its water potential making it more negative
The more solute added the more negative the pH

Question 22

What can you do to make water potential more negative

Answer 22

Add a solute

Question 23

What are the types of solutions in osmosis

Answer 23

Hypotonic
Isotonic
Hypertonic

Question 24

What is a hypotonic solution

Answer 24

Where the solution outside of the cell has a higher solute concentration than the inside of the cell
The water potential is higher outside the cell

Question 25

Where does the water move to when a cell is placed in a hypotonic solution

Answer 25

It moves into the cell by osmosis

Question 26

Where does the water move to when a cell is placed in an isotonic solution

Answer 26

There is no net movement because the concentration is the same in and out of the cell

Question 27

Where does the water move to when a cell is placed in a hypertonic solution

Answer 27

The water moves out of the cell by osmosis

Question 28

What is an isotonic solution

Answer 28

The concentration of solutes is the same in and out of the cell
The water potential is equal in the solution and the cell

Question 29

What is a hypertonic solution

Answer 29

Where the solution inside of the cell has a higher solute concentration than outside the cell
There is a lower water potential outside of the cell

Question 30

What is active transport

Answer 30

Movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using energy and carrier molecules

Question 31

What is the process of active transport

Answer 31

1 - the molecule binds to receptors on carrier proteins
2 - the hydrolysis of ATP (ATP splitting in to ADP and Pi) releases energy
3 - the carrier protein changes shape due to the energy
4 - the molecule is released on to the other side of the membrane

Question 32

Which of the movements of molecules are passive

Answer 32

Diffusion, facilitated diffusion, osmosis

Question 33

Which of the movements of molecules are active

Answer 33

Active transport

Question 34

Which of the movements of molecules have a high to low concentration gradient

Answer 34

Diffusion, facilitated diffusion and osmosis

Question 35

Which of the movements of molecules have a low to high concentration gradient

Answer 35

Active transport

Question 36

Which of the movements of molecules have carrier proteins

Answer 36

Facilitated diffusion, active transport

Question 37

Which of the movements of molecules do not have carrier proteins

Answer 37

Diffusion and osmosis

Question 38

Give an example of a molecule that is transported by diffusion

Answer 38

Oxygen
Carbon dioxide

Question 39

Give an example of a molecule that is transported by osmosis

Answer 39

Water

Question 40

Give an example of a molecule that is transported by facilitated diffusion

Answer 40

Ions

Question 41

Give an example of a molecule that is transported by active transport

Answer 41

Glucose ions