movement of substances

Question 1

define diffusion

Answer 1

net movement of substances from a region of higher concentration to a region of a lower concentration down a concentration gradient

Question 2

when does diffusion stop

Answer 2

when molecules are uniformly distributed on both sides of the membrane also called EQUILIBRIUM

Question 3

at equilibrium, does dye molecules stop moving?

Answer 3

They continue moving at equal rates, but no net movements of dye molecules btwn 2 regions

Question 4

what are the factors affecting rate of diffusion

Answer 4

concentration gradient
size of particle
temperature
distance over which diffusion occurs
surface area to volume ratio

Question 5

how does concentration gradient affect rate of diffusion

Answer 5

steeper concentration gradient, faster rate of diffusion

Question 6

how does size of particle affect rate of diffusion

Answer 6

larger size of particles, slower rate of diffusion (need more kinetic energy to move compared to smaller particle)

Question 7

how does temperature affect rate of diffusion

Answer 7

higher temp, faster rate of diffusion ( avg kinetic energy possessed by particles increase, move faster)

Question 8

how does distance over which diffusion occurs affect rate of diffusion

Answer 8

shorter the distance over which diffusion occurs, the faster the rate of diffusion

Question 9

surface area to volume ratio affect rate of diffusion

Answer 9

larger the surface area to vol ratio. faster the rate of diffusion

Question 10

how does density of medium which diffusion occurs affect rate of diffusion

Answer 10

diffusion occur fastest in gases, liquid solid
because solids have highest density, as particles are closely packed, so diffusion occurs slowest

Question 11

examples of diffusion

Answer 11

root hair cells absorb mineral salts , gaseous exchange

Question 12

definition of osmosis

Answer 12

net movement of water molecules from solution of higher water potential to solution of lower water potential down a water potential gradient through a PARTIALLY permeable membrane

Question 13

what does more concentrated solution mean?

Answer 13

lower water potential

Question 14

what happens when an animal cell is in a solution with higher water potential

Answer 14

water enter cell by osmosis, animal cell swells and burst (called lysis)

Question 15

what happens if a plant cell is placed in a solution with higher water potential

Answer 15

water enters cell by osmosis, central vacuole increases in size and pushes cell contents against the wall, plant cell becomes turgid

Question 16

what happens when an animal cell is in a solution with lower water potential

Answer 16

water leaves cell by osmosis, animal cells shrink and shrivel, spikes appear on cell membrane ( called crenate)

Question 17

what happens if plant cell is placed in solution with lower water potential

Answer 17

water leaves cell by osmosis, large central vacuole decreases in size, cytoplasm and cell membrane will pull itself away from the cell wall, making the cell plasmolysed

Question 18

what happens when water is watered regularly

Answer 18

water enters the plant cell, becomes firm and upright due to turgor pressure, leaves are spreadout, increasing exposure to sunlight

Question 19

what happens when plant has insufficient

Answer 19

water leaves the plant cell, due to lack of tugor pressure, leaves drops, reducing exposure to sunlight