Lab Report limiting factors affecting the rate of photosynthesis report help!

[Emily Krier]

hey guys!!

I m having serious troubles writing my lab report : we made two groups and each group used adifferent concentration of potassium hydrogen carbonate solution.

Ihave a table of results but dont really know what to do with it... standard deviation? the goal was to compare both groupsand see the effect of the concentration on the rate of photosynthessis.

I d be veryyyyyy thankful for any help

[SurajM]

I'm not really sure what you're experiment is about, can you tell me a little more about your procedure?

[Emily Krier]

We measured the height of carbon dioxide produced by using once 10ml and once 30ml of sodium hydrogen carbonate solution.

here is the method:

Before starting the experiment, we took 50g sodium hydrogen carbonate and added 1l of distilled water. This solution was used as the in the method referred to sodium hydrocarbonate solution.

We divided the class into 2 Groups : students 1,2,3,4,5 are part of Group A and students 6,7,8,9,10 are in Group B.

Method for Group A

1. We started by gathering one or two plant stems of the aquatic plant Elodea densa.
2. We filled a beaker with 600ml of Buffer solution and 10ml of sodium hydrocarbonate solution.
3. We placed the plant stem into the big beaker.
4. We restrained the stem under a funnel.
5. We filled a test tube with water or buffer solution.
6. We placed the filled tube over the funnel.
7. We marked the starting level of liquid in the tube.
8. We placed a lamp at 40000 lux (measured with a luxmeter).
9. We marked the height of oxygen produced on the tube after 15 minutes.
10. We marked the height of oxygen produced on the tube after 30 minutes.
11. We marked the height of oxygen produced on the tube after 45 minutes.
12. We had a repetition with new stems and fresh liquids.

Method used by Group B

1. We started by gathering one or two plant stems of the aquatic plant Elodea densa.
2. We started by filling a beaker with 600ml of buffer solution and 10ml of sodium hydrocarbonate.
3. We placed the plant stem into the big beaker.
4. We restrained the stem under a funnel.
5. We filled a test tube with water or buffer solution.
6. We placed the filled tube over the tunnel.
7. We marked the starting level of liquid in the tube.
8. We placed a lamp at 40000 lux (measured with a luxmeter).
9. We marked the height of oxygen produced on the tube after 15 minutes.
10. We marked the height of oxygen produced on the tube after 30 minutes.
11. We marked the height of oxygen produced on the tube after 45 minutes.
12. We had a repetition with new plant stems and fresh liquids.

[SurajM]

i think I can help you, just tell me will both your groups be using both sets of data when doing your experiment? Or is it just based on what your group collected?

[Infested]

You may have entered in your methodologies wrongly as both methods A and B seem to be the same, but nonetheless the one with more hydrogen carbonate should display a larger increase in height of oxygen and subsequently rate of photosynthesis as more CO2 is available to be fed into the Calvin cycle to convert NADPH and ATP back into NADP+ and ADP which will be used in the light dependent reaction. The light dependent reaction involves the splitting of water to produce O2 as a product which is what is measured in your experiment.

Basically what you can do is plot a scatter plot of the height of the oxygen bubble across time and find the best-fit line across all points, of which the gradient will be taken as a measure of rate of photosynthesis.

Edited July 24, 2013 by Infested