University:
Cameron University
Course:
1004 | General Biology
Academic year:

2023
Views:

355

Pages:

1
Author:

Clint W.

Is Bigger Better? Is Smaller Smarter? Introduction: Diffusion is one of the very important processes by which substances such as nutrients, water, oxygen, and cellular wasted are transported between living cells and their environment. This activity will help you explore the relationship between diffusion and cell size by experimenting with model “cells.” In this experiment, you will use deco cubes to which a red cabbage juice indicator has been added. Red cabbage juice is an acid/base indicator that turns yellow in the presence of a base, such as NaOH. Thus the surface of the agar cubes will turn yellow when put into a NaOH solution. The NaOH will continue to diffuse through the cube and gradually turn the entire cube yellow. The guiding question for this lab is thus: (Use this question to help formulate a hypothesis) What determines the efficiency of diffusion throughout the model “cells”? Procedure: 1. 2. 3. 4. 5. Each group will receive 3 cubes: small, medium, and large. Calculate the volume of each cube and record in the data table. Pour 200mL of 0.1M sodium hydroxide solution into a 400mL beaker. Immerse your 3 cubes in the sodium hydroxide solution, noting the time. Let the cubes soak for approximately 25 minutes. (RECORD THE ACTUAL AMOUNT OF TIME THE CUBES WERE SUBMERGED) 6. Periodically, gently stir the solution and turn the cubes over. 7. After 25 minutes, use a spoon or tongs to remove the cubes from the sodium hydroxide solution. 8. Blot the with a paper towel. 9. Measure the depth to which the color has penetrated. Sketch each block in the result table, trying your best to draw actual size. 10. Record your measurements into the data table. 11. Do the following calculations for each cube and complete the following data table: Calculating % diffusion in each cube:  Calculate total volume of each cube (volume = L x W x H)  Calculate volume that did not turn yellow. (That is, calculate total volume of the small portion of the cube that is green – use the same formula L x W x H)  Calculate volume diffused = total volume – volume green  Calculate % diffusion = Volume diffused /total volume x 100 Calculate the surface area of each cube and the surface area to volume ratio:  Calculate the surface area of a cube = L x W x # of sides  Calculate surface area/volume ratio.