Objectives:
LAB: Eggs Surviving Osmosis
Background Information: Osmosis is the movement of water molecules through a selectively permeable membrane into a region of higher solute concentration, aiming to create a state of equilibrium. Osmosis is essential in biological systems, as cell membranes are semipermeable. In general, these membranes are impermeable to large and polar molecules, such as ions, proteins, and polysaccharides, while being permeable to non-polar molecules like lipids as well as to small molecules like oxygen, carbon dioxide and nitrogen. Osmosis provides the primary means by which water is transported into and out of cells. The turgor pressure of a cell is largely maintained by osmosis. Turgor Pressure is the main pressure of cell contents against the cell membrane, determined by the water content. (Think of a water balloon being filled with water.)
Pre-Lab Questions:
1. What is a solvent? What is a solute?
2. What is tonicity?
3. What is osmosis?
Objectives:
o Observe osmosis across the membrane of an egg.
o Measure the amount of water that moves across the egg’s membrane.
o Understand the terms isotonic, hypotonic, and hypertonic.
Materials:
1 Beaker or plastic cup, 600mL
400 mL white vinegar
Water
400 mL of corn syrup
500ml Graduated cylinder
raw egg in shell
Salt
String
Ruler
Triple Beam Balance w/weigh boats
Goggles
Masking tape
Background info cont’d: Define the terms below:
**SAFETY PRECAUTION**
You will be handling raw eggs. You should take care not to break them.
Wash your hands thoroughly after handling them.
If you break your egg, you just lowered your lab grade by a full letter grade!
Procedures:
Day 1:
Vinegar Beaker
1) Using masking tape label 1 beaker with your class period and group number.
2) Look at the raw egg. Note the appearance of the eggshell. Take initial measurements on mass and circumference of each egg. Record data in data table.
3) Use the graduated cylinder to measure 400mL of vinegar and pour into a beaker/cup.
4) Place the raw eggs into the beakers/cup with vinegar. The vinegar should cover the egg. Leave undisturbed for 24hrs.
5) Hypothesize what you think will happen to the size/appearance of the egg after 24hrs and record in data table as Vinegar Hypothesis.
Day 2:
Syrup or Saltwater Beaker
1) Carefully remove egg from Vinegar and place in tray. Pour vinegar down sink and clean out beaker with soap and water. Re-label beaker SYRUP or SALT WATER.
2) Observe the appearance of the egg and record observations in data table as “after the egg was placed in vinegar.”
3) Using a triple beam balance, measure the mass of the egg in grams. Record this number in your data table.
4) Using a piece of string and a ruler measure the circumference of the egg. Record this number in your data table.
5) Measure 400mL of syrup solution (a 50-50 mixture of corn syrup and water) or concentrated salt water solution with a graduated cylinder and add it to the beaker. (Syrup is sticky; clean out graduated cylinder with soap and water.)
6) Carefully place egg in beaker/cup and allow to sit for 24 hrs.
7) Hypothesize what you think will happen to the size of the egg
and record it in data table as Syrup or Salt Water Hypothesis.
Day 3:
Tap Water Beaker
1) Carefully remove egg from salt water or syrup beaker and place in tray. Pour liquid down sink and clean out beaker with soap and water. Re-label beaker as TAP WATER.
2) Observe the appearance of the egg and record observations in data
Table as after egg was placed in syrup or salt water.
3) Using a triple beam balance, measure the mass of the egg in grams. Record this number in your data table.
4) Using a piece of string and a ruler measure the circumference of the egg. Record this number in your data table.
5) Measure 400mL of water with a graduated cylinder and add it to the beaker labeled TAP WATER.
6) Carefully place egg in beaker of water and allow to sit for 24 hrs.
7) Hypothesize what you think will happen to the size of the egg and record in data table as Tap Water Hypothesis.
Final Observations
1) Carefully remove egg from tap water and place in tray. Pour liquid down sink and clean out beaker with soap and water.
2) Using a triple beam balance, measure the mass of the egg in grams. Record this number in your data table.
3) Using a piece of string and a ruler measure the diameter the egg. Record this number in your data table.
4) Dispose of egg in garbage.
5) Clean all lab equipment and return to proper areas.
Analysis and Discussion
1) Egg in Syrup or Salt water:
a: Describe the shape of the egg.
b: Describe why the water moved into or out of the egg.
c: What kind of solution was the syrup or salt water? (hypertonic, hypotonic, or
isotonic) EXPLAIN.
2) Egg in Water solution:
a: Describe the shape of the egg.
b: Describe why the water moved into or out of the egg.
c: What kind of solution was the water? (hypertonic, hypotonic, or
isotonic) EXPLAIN.
Real World Application
1) Why are fresh fruits and vegetables sprayed with water at a market? (hint: it’s not to keep them clean!)
2) In the winter, roads are sometimes salted to melt ice. What does this salting do to the
plants along the roadside? Why? Use key vocabulary terms to explain.
3) Why do dried fruits and dried beans swell when they are cooked? (hint: It’s not because they are wet!) Use key vocabulary terms to explain.
Table 1
|Initial Egg – Day 1 |Egg After Vinegar – Day 2 |
|Mass (g) |Circumference (cm) |Mass (g) |Circumference (cm) |
| | | | |
|Vinegar Hypothesis: |Observations: |
|(if…then…because format) | |
| | |
| | |
| | |
| | |
| | |
Table 2
|Syrup or Salt Water – Day 2 |
|Mass (g) |Circumference (cm) |
| | |
|Syrup or Salt Hypothesis: |Observations: |
|(if…then…because format) | |
| | |
| | |
| | |
| | |
| | |
Table 3
|Tap Water – Day 3 |
|Mass (g) |Circumference (cm) |
| | |
|Tap Water Hypothesis: |Observations: |
|(if…then…because format) | |
| | |
| | |
Multimedia Prezi Oral Presentation - LAB REPORT
| |Prezi Guru (4) |Prezi Pro (3) |Prezi Apprentice |Prezi Novice (1) |
| | | |(2) | |
|Content |Covers topic in-depth with details and |Covers topic well and includes photos |Much of the topic is not |Content is minimal |
| |excellent photos that support science |that support science concepts. |addressed | |
| |concepts and lab protocol. |Subject knowledge on lab concept is |There is a lack of subject | |
| |Subject knowledge on lab concept is |good. |knowledge |OR |
| |excellent. |Most parts of a formal lab report are |Missing several key parts of a | |
|9 x ____ |All parts of a formal lab report are |present (intro, problem, hypothesis, |formal lab report |Did not use lab report |
| |present (intro, problem, hypothesis, |procedures, data, results, conclusion) | |protocol at all. |
| |procedures, data, results, conclusion) | | | |
|Organization |Content is well organized using |Content is organized using headings or |Content is disorganized and |There is no clear or |
| |headings or bulleted lists to group |bulleted lists to group related |difficult to follow. |logical organizational |
| |related material. |material; however, there are some flaws|The student(s) did not plan out|structure to |
| |Flow of presentation is seamlessly |to organization. |the flow or design of |presentation or evidence|
|6 x ____ |aligned with lab procedures. |Flow of presentation is aligned with |presentation; lab procedures |of following lab |
| | |lab procedures. |are not clear. |protocol. |
|Oral Presentation |Interesting, well-rehearsed with smooth|Relatively interesting, rehearsed with |Delivery is not smooth, but the|Delivery is not smooth |
| |delivery that holds audience attention.|a fairly smooth delivery that usually |student(s) is able to hold |and audience attention |
| |Voice level is loud, clear and shows |holds audience attention. |audience attention most of the |is lost. |
| |inflection in tone during appropriate |Voice level is loud and clear; there is|time. | |
|7 x ____ |areas in the presentation. |some inflection in tone during |Voice level is not loud and | |
| | |appropriate areas in the presentation. |clear; student(s) mumbled or | |
| | | |spoke too low for audience to | |
| | | |be engaged. | |
|Mechanics |No misspellings or grammatical errors. |Three or fewer misspellings and/or |Four misspellings and/or |More than 4 errors in |
| | |mechanical errors. |grammatical errors. |spelling or grammar. |
| | | | | |
|3 x ____ | | | | |
| | | | | |
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