Lab Report
Plasma Membrane
It’s time to complete your Lab Report. Save the lab to your computer with the correct unit number, lab name, and your name at the end of the file name (e.g., U2_ Lab_PlasmaMembrane_Alice_Jones.doc).
Introduction
1. What was the purpose of the experiment?
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2. What were the independent, dependent, and control variables in your investigation? Describe the variables used in the part of the experiment with the eggs.
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3. Write a hypothesis based on observations and scientific principles.
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Experimental Methods
1. What tools did you use to collect your data?
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2. Write your procedure. List each step so that another student could follow the procedure and repeat your experiment.
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Data and Observations
1. Record your observations.
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Conclusions
1. What conclusions can you draw about how the plasma membrane contributes to the function of the cell as a whole? Write an evidence-based claim.
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2. Make models of a plant and an animal cell. Include labels for each part of the cells. Use your models to describe how the plasma membrane contributes to how the cell functions as a whole.
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Introduction
1. The purpose of the experiment was to investigate the role of the plasma membrane in cell function.
2. The independent variable in the investigation with the eggs was the concentration of sucrose solution. The dependent variable was the change in weight of the eggs. The control variable was the time the eggs were immersed in the sucrose solution.
3. Hypothesis: Based on observations and scientific principles, it is hypothesized that the eggs immersed in high concentration sucrose solution will lose weight due to osmosis, while the eggs immersed in low concentration sucrose solution will gain weight.
Experimental Methods
1. The tools used to collect data included sucrose solutions of different concentrations, a balance for weighing the eggs, and beakers for holding the sucrose solutions.
2. Procedure:
a. Label six beakers as 'A' to 'F'.
b. Prepare six sucrose solutions of varying concentrations: sucrose solution 'A' with the highest concentration and 'F' with the lowest concentration.
c. Immerse one egg in each beaker, ensuring complete submersion.
d. Leave the eggs in the beakers for a set period, such as 24 hours.
e. After the set time, remove the eggs from the beakers and pat them dry with a paper towel.
f. Weigh each egg individually using a balance and record their weights.
g. Analyze the data and note any changes in weight for each egg.
Data and Observations
1. Record your observations:
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Conclusions
1. The plasma membrane plays a crucial role in the functioning of the cell as a whole. It regulates the movement of substances into and out of the cell, maintaining cellular homeostasis. This is evidenced by the egg experiment where the eggs in different sucrose solutions experienced changes in weight due to osmosis, which is controlled by the plasma membrane.
2. In the plant cell, the plasma membrane surrounds the cell, separating it from the external environment and allowing for selective transport of substances. It contributes to the cell's structural support and protection. In the animal cell, the plasma membrane performs similar functions, regulating the movement of substances and providing a boundary between the cell and its surroundings. This allows the cell to maintain its internal environment and carry out necessary functions.
Introduction:
1. The purpose of the experiment was to investigate the role of the plasma membrane in cell functioning.
2. In the investigation with the eggs, the independent variable was the type of solution used to soak the eggs (e.g., water, saltwater, vinegar), the dependent variable was the change in the egg's mass and appearance, and the control variable was the time for which the eggs were soaked in the solution.
3. Based on observations and scientific principles, a hypothesis could be: If the plasma membrane is permeable to water and certain solutes, then the eggs soaked in different solutions will experience changes in mass and appearance due to osmosis and diffusion.
Experimental Methods:
1. The tools used to collect data in this experiment were a balance to measure the egg's mass before and after soaking, a ruler to measure dimensions, and a microscope (optional) to examine the egg's structure.
2. The procedure for the experiment could be as follows:
a. Gather the materials: eggs, various solutions (water, saltwater, vinegar), balance, ruler, and microscope (optional).
b. Measure and record the mass of each egg before soaking.
c. Place each egg in a separate container filled with a specific solution (e.g., water, saltwater, vinegar).
d. Allow the eggs to soak in the solutions for a specific time period (e.g., overnight).
e. Remove the eggs from the solutions and gently blot them with a paper towel to remove excess moisture.
f. Measure and record the mass and appearance (color, texture) of each egg after soaking.
g. Optional: Use a microscope to observe any structural changes in the egg.
Data and Observations:
1. Record your observations by describing any changes in the egg's mass, appearance, and structure after soaking in different solutions. Include specific details and measurements.
Conclusions:
1. Based on the conducted experiment, the plasma membrane contributes to the cell's function as a whole by regulating the movement of substances in and out of the cell. This process, known as selective permeability, allows the cell to maintain homeostasis and perform essential functions such as nutrient uptake and waste removal. The evidence-based claim could be: The observed changes in egg mass and appearance after soaking in different solutions indicate that the plasma membrane's permeability to water and solutes has a direct impact on the cell's overall function.
2. Models of a plant and an animal cell can be created, including labels for each part. The plasma membrane can be highlighted and described as the outer layer of the cell, separating the cell's internal components from the external environment. Its role in regulating the movement of substances and maintaining cell homeostasis can be emphasized, allowing the cell to function as a whole.