I have data for the rate of photosynthesis for two species for my biology A level coursework, I am required to do a statistical test to show significance but I'm unsure of a test for comparing two rates. Any advice would be appreciated, thanks.

I have data for the rate of photosynthesis for two species for my biology A level coursework, I am required to do a statistical test to show significance but I'm unsure of a test for comparing two rates. Any advice would be appreciated, thanks.
Do you mean two rates as in two average numbers, one for each species? The type of test you can use may depent on some particular properties of your data. For example, are variances equal and is your 'rate of photosynthesis' normally distributed? If this is the case, I think an 'independent ttest' as well as an 'ANOVA' will work. Both compare two mean values, but since ANOVA is mostly used when multiple ttests are required I think an independent ttest will do the job. Think you can work with this?
Hi jblox,
First calculate the rate of photosynthesis for each species, using your raw data on Oxygen output, then perform an unpaired ttest to see if there is a significant difference in photosynthesis rate between the two species.
http://www.marietta.edu/~spilatrs/biol103/photolab/photosyn.html
http://en.wikipedia.org/wiki/T_test
Best wishes,
Tridimity
P.S. I think this is correct, but please check with someone else before you take my word for it, since it's actually quite important that you get this right!
Do you mean like this?
species A: V1; V2; V3; V4; V5; V6; V7; V8; V9; V10
species B: V1; V2; V3; V4; V5; V6; V7; V8; V9; V10
What exactly do you want to know? The difference between each Vpair (V1A compared to V1B, V2A compared to V2B etc.)? Or the difference between oxygen output/minute in A compared to oxygen output/minute in B? For the latter, you can simply calculate both rates (devide V10 by ten) and use an independent ttest to compare.
Yes, it would be most informative to compare the overall photosynthesis reaction rates between the two species, rather than trying to compare the individual Oxygen outputs at each time point.
This Wikipedia link provides some information on how to perform an independent (unpaired) ttest  see section 5.3: Student's ttest  Wikipedia, the free encyclopedia
Scroll down to section 6 for worked examples.
Best wishes,
Tridimity
Oh, and if you have access to SPSS, you can enter your data and perform an unpaired ttest via Analyse > Compare Means > Independent Samples ttest
I have sorted it now. Thanks to everyone that helped out.
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