osmosis DEFINITELY IN EXAM

Question 1

define osmosis

Answer 1

the net movement of water particles from a dilute to concentrated solution through a partially permeable membrane

Question 2

what happens if a plant cell is placed in water

Answer 2

water will move into the cell by osmosis and the cell will expand (the cell wall prevents the cell from bursting so it becomes turgid)

Question 3

what happens if a plant cells is placed in a concentrated solution

Answer 3

water moves out of the plant cell by osmosis this causes the cell to shrink (the cell becomes flaccid)

Question 4

what plant do you usually use to investigate the effect of osmosis on plant tissue

Answer 4

potato

Question 5

what is the method for investigating the effect of osmosis on plant tissue

Answer 5

peel the potato (skin acts as a barrier and can limit osmosis)
use a cork borer to produce 3 cylinders of potato (using a cork borer makes all 3 cylinders have the same diameter)
use a scalpel to trim the cylinder of potato to 3cm
measure the length of each cylinder with a ruler and the mass of each cylinder with a balance
place each potato cylinder into a test tube
add 10cm cubed 0.5 molar sugar solution to the first test tube
add 10cm cubed 0.25 molar sugar solution to the second test tube
add 10cm cubed distilled water to the third test tube
leave potatoes overnight to allow osmosis to occur
remove potato cylinders and gently roll them on paper to remove any surface moisture
measure the length and mass of the cylinders

Question 6

how do you calculate percentage change

Answer 6

percentage change= (change in value/ original value) x 100

Question 7

in water why does the potato cylinder gain mass

Answer 7

water moves into the potato cylinder by osmosis so the potato cylinder gains mass (in water)

Question 8

in concentrated sugar solution why does the potato cylinder lose mass

Answer 8

water moves out of the potato cylinder so the potato cylinder losses mass (concentrated sugar solution)

Question 9

when the concentration outside the cell is the same as inside the cell what happens to the rate of osmosis

Answer 9

no osmosis can occur

Question 10

is the cytoplasm a dilute or concentrated solution and why

Answer 10

the cytoplasm is a relatively concentrated solution because it contains a low concentration of water

Question 11

in an animal cell if the cell is placed in a dilute solution what will happen to the cell

Answer 11

the cell will swell (expand) and possibly burst

Question 12

in an animal cell if the cell is placed in a concentrated solution what will happen to the cell

Answer 12

the cell will shrink and shrivel