Life with Oxygen Lab

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10.19.2011

TITLE: The Importance of Oxygen for Life
PURPOSE: To determine whether test tubes filled with bacteria, a few salts, distilled water, and glucose would grow in the presence or absence of oxygen. By adding oxygen to certain tubes and withholding it from other tubes, one can determine which bacteria grow the most efficiently. HYPOTHESIS: The test tubes of bacteria with oxygen will grow and thrive over the test tubes without oxygen. METHODS: Using the data shown in Table 7-A-1, construct two graph lines on the same graph. First plot “concentration of glucose” against the “number of bacteria” in series A (tubes without air). Label the vertical axis “millions of cells per ml” and the horizontal axis as “glucose (mg/100ml).” For the second graph plot the “concentration of glucose” against the “number of bacteria” in series B (tubes with air). Label the first graph line: “Growth without air.” Label the second line “Growth with air.” RESULTS:

1.) Bacteria numbers in tubes without air only grew to a certain level and then growth stopped/leveled off. 2.) Bacteria numbers in tubes with air seemed to grow and multiply exponentially. **** See Attached Data Graph ****

ANALYSIS:
1. What are the most obvious differences between the two graph curves? The curve for the tubes with oxygen go up and the the curve for the tubes with no oxygen level off and peak quickly due to no more growth. 2. Look at Table 7-A-1 and compare tubes 4A and 4B. How many times greater was the growth when air was present? The growth was 5 times greater in tube 4B. 3. Compare the other tubes in A and B series at various glucose concentrations. How much greater is the growth in air for each pair of tubes from 1A and B through 5A and B? It starts at 4 times greater with air, peaks at 5 times greater, and ultimately decreases back down to 4.67 times greater than with air. 4. Notice that the number of bacteria not given for tubes 6B,7B,8B, and...
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