diffusion, osmosis and active transport

Question 1

definition of osmosis

Answer 1

the movement of free water particles from a high water concentration to a low water concentration over a semi-permeable membrane

Question 2

isotonic solution

Answer 2

the solution outside the cell has the same water potential as inside the cell - no movement

Question 3

hypotonic solution

Answer 3

the solution outside the cell has a higher water potential then inside the cell - movement of water into the cell

Question 4

hypertonic solution

Answer 4

the solution outside the cell has a lower water potential then inside the cell - movement of water out of the cell

Question 5

turgid

Answer 5

cell membrane and cytoplasm pressing against cell wall - water has moved into cells

Question 6

plasmolysed

Answer 6

cell membrane pulled away from cell wall as cytoplasm decreased - water moved out of the cells

Question 7

definition of diffusion

Answer 7

random movement of particles from an area of high concentration to an area of low concentration

Question 8

list factors that affect diffusion

Answer 8

temperature, concentration gradient, distance, SA

Question 9

how does temperature affect diffusion

Answer 9

higher temperatures = molecules have higher kinetic energy and move faster so rate increases

Question 10

how does concentration gradient affect diffusion

Answer 10

if there is a large difference in concentration gradient, molecules will diffuse quicker

Question 11

how does distance affect diffusion

Answer 11

diffusion will take longer if molecules have further to travel therefore cells have a short diffusion distance

Question 12

how does surface area affect diffusion

Answer 12

a larger SA speeds up diffusion as there are more opportunities for the molecules to move

Question 13

definition of active transport

Answer 13

the movement of molecules from a an area of low concentration to an area of high concentration using ATP

Question 14

describe an experiment to show the relationship between surface area and diffusion

Answer 14

• Agar cubes of different sizes are placed in an acid
• the acid diffuses into the cubes and reacts with the alkali inside, turning the indicator colourless
• the smallest cubes becomes colourless the quickest as it has a larger SA

Question 15

describe an experiment to show the relationship between concentration gradient and osmosis

Answer 15

• potato cubes are placed in sucrose solutions of different concentrations
• osmosis will occur until the water potential of the potato and solution are the same
• if the solution has a higher water concentration, water will move into the potato and will increase its mass
• if the solution has a lower water concentration, water will move out of the potato and will decrease its mass