B2.2.

Question 1

give 2 examples of diffusion of gases and solutes in biological processes

Answer 1

oxygen and carbon dioxide moving into and out of cells

food molecules moving from the bloodstream into our body cells

Question 2

definition of diffusion

Answer 2

net movement of particles from a region of high concentration to a region of low concentration down the concentration gradient

Question 3

definition of concentration gradient

Answer 3

gradual difference between concentrations

Question 4

what is a case when there is no concentration gradient (at a state of equilibrium)

Answer 4

when there are equal number of molecules on each region

Question 5

what are some factors that affect the rate of diffusion

Answer 5

surface area
temperature
concentration gradient
distance

Question 6

how does surface area affect the rate of diffusion

Answer 6

as surface area increases, the rate increases. There is more space for particles to diffuse through

Question 7

how does temperature affect the rate of diffusion

Answer 7

as temperature increases, the rate increases. Molecules gain kinetic energy causing them to move faster

Question 8

how does concentration graident affect the rate of diffusion

Answer 8

as concentration gradient increases the rate increases

Question 9

how does diffusion distance affect the rate of diffusion

Answer 9

as diffusion distance increases, the rate decreases. molecules need to travel further

Question 10

what kind of a process is diffusion

Answer 10

passive process which requires no energy to occur

Question 11

definition of osmosis

Answer 11

net movement of water molecules through a partially permeable membrane from a region of high water potential to a region of low water potential

Question 12

what is partially permeable membrane

Answer 12

it allows small molecules to enter through but not larger solute molecules

Question 13

what will an area of higher concentration of water be

Answer 13

area with low concentration of solute - dilute solution

Question 14

what will happen if a cell is placed in a dilute solution (solution of pure water, low solute concentration)

Answer 14

water will enter the cell by osmosis. The cytoplasm and vacuole will swell but the cell won’t burst as the cell wall provides strength. (turgor pressure)

Question 15

what is turgor pressure

Answer 15

pressure of the water pushing against the cell wall

Question 16

what does turgor pressure help the cell with

Answer 16

it helps plants to maintain their structure

Question 17

what will happen if a cell is placed in a concentrated solution (solution of high solute concentration)

Answer 17

water will leave the cell through osmosis as the water concentration inside the cell is higher than the water concentration outside. Cytoplasm will shrink and it will become flaccid (wilting)

Question 18

definition of being plasmolysed

Answer 18

when the cytoplasm shrinks so much (because the solution is so concentrated) that the cell membrane is pulled away from the cell wall

Question 19

water potential and osmosis in plant cells

Answer 19

water in the soil is more dilute (lower solute concentration) than the solution in the root hair cell. Water will enter the root hair cell through osmosis

Question 20

water potential and osmosis in animal cells

Answer 20

animal cells are not protected by cell walls and can thus burst if they don’t control osmosis properly

Question 21

what happens if you put a animal cell into a solution of low water potential

Answer 21

it will become crenated (shrink)

Question 22

what happens if you put a animal cell into a solution of high water potential

Answer 22

it will burst