Homework Sourse6 What does the agar blocks represent in this lab 7 A What c
6. What does the agar blocks represent in this lab?
7. A. What color is the pH indicator phenol red at neutral pH?
B. What color is the pH indicator phenol red at acidic pH?
8. What is actually diffusing into the agar blocks?
9. A. The agar blocks start with a concentration of H+ ions of 1x 10^-7 . If you calculate the pH, is it acidic, basic or neutral?
B. What other common substance has a similar concentration of H+ as the agar blocks at the beginning of the experiment?
C. If the concentration of H+ ions inside of a cell equals the concentration of H+ ions outside of a cell, what happens to the diffusion of H+?
D. Therefore, the color of the agar block will be _______ ?
10. What is the purpose of a trial in an experiment?
Pre-Lab: Read the Introduction to this lab below. Complete the Pre-Lab Questions to be turned in at the beginning of your next lab. Living organisms and cells are constantly exchanging materials with their surroundings in order to stay alive. We take in food molecules for energy and building materials for our tissues and organs and eliminate waste. We take in oxygen when we breathe in and eliminate the waste product carbon dioxide when we breathe out. The cells of our body are surrounded by bodily fluids, which are mostly water but also contain many different molecules. So, the cell, like our bodies, must control or regulate what goes in and out. Cells do that by controlling what crosses the cell or plasma membrane. In other words, the plasma membrane is selectively permeable. Once molecules cross the plasma membrane, they must move through the cytoplasm rapidly enough to allow the cell to function. There are a number of different ways that molecules can cross the selectively permeable plasma membrane, based on the size and the chemical nature of the molecules. Some molecules move by a process called passive transport. Remember that all molecules are constantly moving and the direction of this movement is random; this molecular movement is referred to as Brownian motion. In passive transport, molecules move from high concentration to low concentration Solution
1. The agar blocks represents the process of diffusion in this lab. Diffusion is the net passive movement of particles from a region in which they are higher in concentration to a region in which they are in lower concentration. Agar blocks demonstrate this process. It also demonstrates how surface area to volume ratio is important in diffusion.
2. A. At neutral pH, the color of indicator phenol red is red.
B. At acidic pH, that means the pH lower than 7, the indicator shows a yellow color.
3. The indicator present in the agar blocks diffuses in the media. As the indicator changes color depending upon the pH, so when the diffusion occurs the phenol red indicator changes its color and gets diffused in this lab.
