Osmosis and Diffusion (Mahya Babaie)
Research Question and Hypothesis
How Do Hypotonic, Hypertonic, and Isotonic Solutions Affect the Water Movement of a Cell?
Standards
7th Grade California Content Standard:
Students know cells function similarly in all living organisms.
Scientific progress is made by asking meaningful questions and conducting careful
investigations.
Students should develop their own questions and perform investigations.
Introduction:
Osmosis is the diffusion of water through a selectively permeable membrane. Water will diffuse into a cell or out of a cell depending on the concentration of water on each side of the membrane. Water will alway move from an area of greater concentration to an area of lesser concentration.
Experimental Design:
Day 1:
1. Observe three eggs. Record your observations.
2. Use the triple beam balance to find the mass of your eggs. Record. Use the measurement tape to measure the circumferences. Record.
3. Use the masking tape to label your beakers.
4. Pour 200 mL of vinegar into one of the beaker.
5. Gently set your eggs into the beaker.
6. Set the beaker aside for 24 hours.
Day 2:
1. Observe the eggs in the beaker. Record your observations.
2. Use the spoon to remove the eggs from the beaker.
3. GENTLY rinse the eggs and find its masses. Record.
4. Using the graduated cylinder, measure the amount of vinegar left in the beaker. Record.
5. Rinse the beaker.
6. Pour 200 mL of corn syrup into one beaker; 200 ml of vinegar in another beaker and 200 ml water in the third beaker.
7. GENTLY place one egg into each of these three beakers
8. Set the beakers aside.
Day 3:
1. Observe the egg. Record your observations.
2. Use the spoon to remove the egg from the beakers. The egg is still very, very fragile.
3. GENTLY rinse the egg and find its mass. Record.
4. Using the graduated cylinder, measure the amount of liquid in the beaker. Record.
Day 4:
1. Observe the egg. Record your observations.
2. Use the spoon to remove the egg from each beakers. The egg is still very, very fragile.
3. GENTLY rinse the egg and find its mass. Record.
4. Using the graduated cylinder, measure the amount of liquid in each beakers. Record
Independent variable
Time
Dependent variables
Egg's mass
Series
Study the mass and size of eggs (dependent variable) as a function of time (independent variable) at various timeline (series).
Constants and Controls
We have a control egg (egg in water ) so we can compare the experimental eggs to it. The temperature is held constant all the time.
Materials
1. Few raw egg (3)
2. Large beakers (3)
3. Vinegar
4. Graduated cylinder
5. Spoon
6. Corn syrup
7. Distilled water
Procedures
Refer to experimental design.
Sample data and graphs
Day 1
Day 2
Day 3
Day 4
Include raw data and graphs. Make certain to include units in all measurements, titles on all graphs, and labels on all axes.
Make a LINE GRAPH to compare the change in the egg’s mass as the
type of liquid changed. Remember title & labels.
Analysis & Conclusions
Analyze the data and draw conclusions relevant to your research question and hypothesis.
1. Based on your observations, what effect did the vinegar have on the egg?
2. Was the vinegar (Day 1) a hypotonic, hypertonic or isotonic solution? ______________
Explain how your data and observations support this conclusion.
3. Was the syrup (Day 2) a hypotonic, hypertonic or isotonic solution? ________________
Explain how your data and observations support this conclusion.
4. Was the water (Day 3) a hypotonic, hypertonic, or isotonic solution? ________________
Explain how your data and observations support this conclusion.
Photos & Movies