SVHS LAB BIOLOGY
Present
for lab
NAME: ____________________
PERIOD: 1 2 3 4 5 6
FACTORS THAT EFFECT OSMOSIS
INTRODUCTION: Water moves into and out of cells by a passive process called osmosis. The term
“passive” means that energy of the cell is not used in the process osmosis. Different
factors can effect the rate of osmosis; water concentration, surface area to volume
ratio for the cell, and temperature. In this lab you will see how plant cells react when
placed in hypertonic and hypotonic solutions. You will also be able to determine what
molar solution is isotonic to the cells of the potato.
QUESTIONS:
HYPOTHESIS:
If surface area increases will osmosis occur faster?
• If surface area to volume ratio is increased will osmosis occur faster.
• Will increasing the solution strength increase the rate of osmosis?
•
IF the core size is larger, THEN osmosis will occur faster.
IF the Surface area/Volume ratio is increased, THEN osmosis will occur faster.
IF the solute concentration is increased, THEN osmosis will occur faster.
PROCEDURE:
1)
Label 6 test tubes using masking tape:
Dist. Water, .2 M. sucrose, .4 M. sucrose, .6 M. sucrose,
.8 M. sucrose , 1.0 M. sucrose.
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
Get 18 potato cores of the same diameter. (Record their diameter in the space provided)
Cut all 18 cores to same length as the shortest core. (Record their length in the space provided)
Mass each group of 3 cores and record their initial mass in the space provided.
Place 3 cores in each test tube that has been labeled as directed in step #1.
Pour solutions into the test tubes such that the cores are just covered with solution.
Allow cores to soak 45 minutes.
Calculate the surface area and volumes of the cores your group used. Record in area provided.
Remove cores and blot them dry by rolling them across a paper towel. (Do not squish them!)
Mass each group of cores. Record their final mass in the table.
Calculate the percentage change by dividing the change in mass by the initial mass and multiplying by
100. Record this is the proper space in the table.
NOTES:
•
•
•
•
Be sure to keep track of the mass for each group of potato cores. DO NOT MIX UP!
Be sure to measure in grams.
You must weigh the potato before (initial) and after (final) soaking.
Be sure to “reZero” the scale each time you weigh a potato core.
Core Dia.=
mm
2
3
Core S.A. =_____mm Core Vol.=
mm
SA: Vol = _______
Core Length = _________mm
SOLUTION
STRENGTH
(A)
INITIAL
MASS
SMALL CORES
(B)
© (C= B-A)
FINAL MASS
WT LOSS OR GAIN
(D) % CHANGE
(C/A) X 100 = % CHANGE
DISTILLED
WATER
.2 M SUCROSE
.4 M SUCROSE
.6 M SUCROSE
.8 M SUCROSE
1.0 M
SUCROSE
Core Diam.=
mm
Core S.A. =
2
mm
Core Vol.=
3
_mm
S.A: Vol=
___
Core Length= __________mm
SOLUTION
STRENGTH
DISTILLED
WATER
.2 M
SUCROSE
.4 M
SUCROSE
.6 M
SUCROSE
.8 M
SUCROSE
1.0 M
SUCROSE
(A)
INITIAL
MASS
LARGE CORES
(B)
(C)
(C= B-A)
FINAL MASS
WT LOSS OR GAIN
(D) % CHANGE
(C/A) X 100 = % CHANGE