Thursday, November 29, 2012

In the following procedure, the purpose of the experiment is to test an abiotic or biotic factor to see observe the effect it  has on the photosynthesis rate. Specifically, this experiment is designed to test the effects of light intensity on the rate of photosynthesis. I predict that the more light that is filtered out and prevented from reaching the leaf disks, the lower the rate of cellular respiration will be. It is important to keep temperature, time of exposure, amount of solution constant, while varying the light sources intensity set up the initial portion with the plant disks and and the plungers [including gathering all materials necessary and the set up for preperation], complete the following steps:

Step 1.   On the lab table, place four sheets of printer paper provided (approx 11x8 inches) by each ring hole in the lab table.

Step 2.  Make sure it is positioned on the table directly below where the four cups will be placed on it.

Step 3.  Gather one more piece of paper, one black sharpie, four medical syringes (10mL), 14 mesh screens, hole punch, 50 mL beaker, 5 mL syringe, timer, 20 mL of liquid dish soap (2x concentrated), clamp light, clamp for the light, beveled lab pole.

Step 4.  In all four cups, pour the 2NaHCO3  until there is approx 3 cm from the top of the cup.

Step 5. Using the 5mL syringe, add 5 drops of soap into the mixture and use glass stirrer to gently mix. AVOID creating any bubbles if possible.

Step 6.  Use the hole punch to cut out 40 leaf disks from the spinach leaf( note you will need more than one most likely four) over the white piece of paper by the sink.

Step 7. Carefully brush the ten disks into each syringe tube after having removed the plunger. Repeat this for all syringes. Then put the plunger back in. Leave only about 1 mL in the barrel.

Step 8. Draw 5mL into the barrel of all four syringes. Then invert and slowly and carefully expell the remaining air in the tube for all for.

Step 9.  To create a vaccum, cover the tip of the syringe and draw back the plunger and hold it for ten seconds, then slowly release. Do this for the rest of the syringes but do so one at a time to get the leaf disks to sink.

Step 10.  Remove the plunger and pour the contents of one syringe into one of the cups filled with the soapy solution and set it on the paper beneath the light uncovered.

Step 11. Repeat this with another syringe and cup, this time covering the top with saran wrap.

Step 12.  Repeat but cover the cup with 2 mesh screens.

Step 13. For the fourth syringe, do the same but this time covering the cup with four layers of mesh screen.

Step 14.  Turn on the light and begin recording data for the initial reading, and again at every one minute interval to determine how many disks have begun floating.

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