Lab Plasmolysis

1. Introduction

a. Background Information- Plasmolysis is the shrinking of the cytoplasm of a plant cell in response to diffusion of water out of the cell and into a hypertonic solution surrounding the cell. During plasmolysis the cellular membrane pulls away from the cell wall.

b. Purpose- The purpose of this experiment is to determine the effects of different salt solutions on Elodea plant cells.

c. Hypothesis- Knowing that plasmolysis involves the shrinking of the cytoplasm in a cell wall after diffusion of water in hypertonic solutions; I predict that both the area and the perimeter of the cell will decrease in size.

2. Procedure

a. Equipment used

i. Onion epidermis

ii. 30% NaCl

iii. Cover slip

iv. Microscope

v. 1. Prepare wet mount

vi. 2. Add two drops of 30% NaCl

vii. Wick this salt solution under the cover slip by touching a piece of absorbent paper towel to the fluid at the opposite edge of the cover slip.

b. Collection of data

i. N/A

3. Results

a. Description of Data

i. The first step was to cut out a piece of onion and remove a single layer. The layer was then placed on a slide and a drop of water was added. Then we used a microscope to find the onion cells under 10X and then 40X. Next, we placed a paper towel along one edge of the slide and added drops of 30% NaCl (salt) solution and replaced the fresh water. After plasmolysis took place, we observed the cell.

4. Discussion

a. Support of Hypothesis- My original hypothesis was correct in that both the final perimeter and area were less than the starting values. This occurred because water moved out of the cell, into the hypertonic, meaning a high solute concentration, salt solution, which led to the shrinking of the cytoplasm, a process called plasmolysis. If the

solution added had been hypotonic, meaning it had a low solute concentration,

then plasmolysis would not have occurred, and the perimeter and area would not

have increased.

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