Dennis M. Feliciano
Grand Canyon University
BIO100L Biology Concepts Lab
June 25, 2011
Raisins (larger is better)
Four small containers (i.e., drinking cups or clear glasses) A metric ruler
Methods and Procedure
Place 1 cup (236 ml) of water in each of the 4 containers.
In 2 of the containers, add 1 tablespoon (14.8 ml) of table salt and mix well. Measure the length and width of a raisin and place it in 1 of the plain water containers. Measure the length and width of a second raisin and place it in one of the salt water containers. Measure the length and width of a grape and place it in the second of the plain water containers. Measure the length and width of a second grape and place it in the second of the salt water containers. After 1 hour, remove and measure the length and width of each piece of fruit and return it to the appropriate container. Note any physical changes in the fruit and describe their appearance. After 24 hours, remove and measure the length and width of each piece of fruit. Note any physical changes in the fruit and describe their appearance.
Written Lab Report
Address the following questions:
Osmosis is a physical-chemical process associated with the behavior of water as a solvent in a solution to a semipermeable membrane to the solvent (water) but not the solutes. Such behaviour involves a simple diffusion through the membrane of water without expending energy. Osmosis is an important biological phenomenon for cellular physiology of living things.
State a prediction for each experiment (all 4).
I predict that the raisin submersed in the fresh water solution will expand and increase in size. The grape submersed in the fresh water solution will not change in size. The raisin submersed in the salt water will absorb water until the water solute level is balanced. The grape submersed in the salt water will shrink because water will be drawn out of the grape.
State the independent variable; state the dependent variable.
The independent variable is the concentration of the water solution and the dependent variable is the change (if any) in cell size of each fruit.
What controlled variables were used in this experiment (what stayed the same in all trials)?
The length of time submersed in the water solution. The temperature. The amount of water used in each cup. The amount of salt in the salt water solute.
State a hypothesis for the experiment.
Hypothesis: The raisins in both the fresh and salt water wil expand in size because the water content inside the raisin is lower than the water outside the cell. The grape in fresh water may not change in size at all because there is water content inside. The grape submersed in the salt water solution will shrink because the solution outisde of the grape is hypotonic so water will flow out of the grape causing it to shrink.
Present all data in a table. List all data points and calculate the mean length and width for each experiment at the start, after 1 hour, and after 24 hours – raisin/water, raisin/salt water, grape/water, and grape/salt water.
|Raisin/Water |Raisin/Salt Water |Grape/Water |Grape/Salt Water | |Before Submersion: |Before Submersion: |Before Submersion: |Before Submersion: | |11cm Wide |11cm Wide |17cm Wide |15cm Wide | |17cm Long |15cm Long |18cm Long |16cm Long | |After 1 Hour: |After 1 Hour: |After 1 Hour: |After 1 Hour: | |9cm Wide |11cm Wide |17cm Wide |15cm Wide...