Name Section Today you will design an investigation to explone . Choose one or m
ID: 280239 • Letter: N
Question
Name Section Today you will design an investigation to explone . Choose one or more of the cell models available: emonstrate your understanding of how water ecalcified egg, dialysis tubing, grape, and/or potato core. You can use a combination of cell models to compare results and other molecules pass through the cell membrane. USE GLOVES AND GOGGLES 5. Materials: Write down the materials and solution concentrations you will use in the 6. Methods and Procedures: Outline methods/ procedures you and your lab partner will perform today. You will need to calculate percent weight change. approves the 7. Be sure your instructor experimental design before you begin 8. Results: Create a data table to collect Methods/Procedures 1. Review lecture notes and textbook information data and record observations. Both qualitative and quantitative data should be collected (See Table 6.1 and Figure 6.2). Keep accurate observations, measurements, and to understand water movement through the cell membrane (osmosis) calulation records in your laboratory manual 2. Follow the scientific process to design a series of investigations or experiments to demonstrate your understanding of osmosis terminology: hypertonic, hypotonic, and isotonic Graph data collected using Microsoft Excel or other graphing software (see Appendix IIIl 9. Discussion: Analyze, critique, and interpret 3. Hypothesis: Formulate a hypothesis. Make 10. Lab Report Information-Your instructor will 11. Use Appendix IV: How to Write a Formal your results. give you further instructions laboratory report. a prediction, pose a problem, or write an explanation (if... then....because) statement Identify independent and dependent variables. to help you write the Control (SinF1 f you use dialysis tubing fellorw the felloaring procadture to fil the dialysis tubing.5 es 12.24 Fold one end te securely Add appropriate Press sighly to renove most b tele dialysis tube Rinse bag place in beaker oontaining Epproprans solution FIGURE 6.1 How to fill and close a dialysis tube. 42 Laboratory 6 How do Water and Other Molecules Enter and Leave Cells?Explanation / Answer
Aim:
To demonstrate the process of osmosis across a semipermeable membrane using a de-shelled egg.
Introduction:
When two solutions of different concentrations are separated by a selectively permeable (semipermeable or differentially permeable) membrane, the solvent molecules spontaneously move from the zone of lower solute concentration (higher solvent concertation) to the region of higher solute concentration (lower solvent concertation), to reach an equal concentration state on each side of the membrane. This process is termed as osmosis.
Cell membranes are selectively permeable membrane. When a cell is surrounded by different concentrations of solutions, different effects are observed:
Hypertonic solution: Concentration of solution outside the cell is higher compared to cell cytoplasm, water from the cell moves out of the cell and the cell shrinks.
Hypotonic solution: Concentration of solution outside the cell is lower compared to cell cytoplasm, water enters the cell moves out of the cell and the cell swells (become turgid).
Isotonic solution: Concentration of solution outside the cell is same as that of cell cytoplasm, no net water movement.
Hypothesis: De shelled egg act as mass of cells surrounded by semipermeable membrane. When placed in 20 % solution of Sodium Chloride, it acts as hypertonic solution, hence water should leave the egg, causing decreased volume (weight) of the egg.
Method:
Results:
Egg
Egg 2
Initial observations:
Initial observations:
In vinegar:
(weight in grams)
Weight difference
In 20% NaCl:
(weight in grams)
Weight difference
T5 = 73.00,
0.78
T5 = 73.74
0.49
T10 =72.94
0.84
T10 =71.17
3.06
T15 =72.20
1.58
T15 =70.98
3.25
T20 =72.34
1.44
T20 =70.55
3.68
T25 =72.29
1.49
T25 =70.44
3.79
T30 =72.40
1.38
T30 =70.07
4.16
Average difference: weight decreased by:
1.252
3.071
Conclusions:
As per the observation, there is not much difference in weight of egg 1, and the average difference is 1.25 compared to initial weight. While in case of egg 2, there is an increase in weight from the initial weight, and the observed weight difference is 3.07. This indicate that, when the de-shelled egg was placed in 20% NaCl solution (hypertonic), water moved out the egg (egg 2), which was reflected by decrease in weight, compared to the control (almost isotonic).
This proved the hypothesis of osmosis.
If the egg was placed in distilled water, water would enter the egg and cause increase in weight of the egg.
Also egg floats in NaCl solution, as it is denser, while sinks in vinegar which is lighter.
Egg
Egg 2
Initial observations:
Initial observations:
- Egg sinks
- Weight at T0:73.78 g
- Egg floats
- Weight at T0: 74.23g
In vinegar:
(weight in grams)
Weight difference
In 20% NaCl:
(weight in grams)
Weight difference
T5 = 73.00,
0.78
T5 = 73.74
0.49
T10 =72.94
0.84
T10 =71.17
3.06
T15 =72.20
1.58
T15 =70.98
3.25
T20 =72.34
1.44
T20 =70.55
3.68
T25 =72.29
1.49
T25 =70.44
3.79
T30 =72.40
1.38
T30 =70.07
4.16
Average difference: weight decreased by:
1.252
3.071
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.