Simulation 2 - Optimization of Photosynthesis

web.pdx.edu/~rueterj/bi445/simulations/sim2.htm

Simulation 2 - Optimization of photosynthesis

The purpose of this simulation is to examine the effects of changing the paramters and therelative amounts of Pmemb and Penz on the net rate of photosynthesis on two species.

Part A: Comparison of the parameters Pmax and Ik:

** in class I'll show you how to name cells **

Constants for part A	initial value or equation	units
PmaxA	0.5	mol C fixed mol C^-1 hr^-1
IkA	100	umol photon m^-2 s^-1
PmaxB
IkB

ProductivityA	PmaxA*TANH(Light/IkA)	mol C fixed mol C^-1 hr^-1
ProductvityB	same with B parameters
range of light (X axis)	0 to 2000	umol photon m^-2 s^-1

It should look something like this:

By changing the paramters, you should answer

Question 1: Describe the effect of Pmax and Ik on the shape of the P vs. I curve.
Question 2: Pick non-saturating light levels (i.e. less than Ik). Can you get the same P at the same light by adjusting Pmax?

Part B: Optimization of the components of photosynthesis.

The point of this exercise is to compare the photosynthetic output by varying the relative amount of Pmemb and Penz. The total amount of each of these together is 10 units (10 fmolC/cell). The potential output of Pmemb depends on light, the efficiency and the amount of Pmemb. The potential output of Penz depends on the amount of Penz and its efficiency The output of this system depends on the minimum of the outputs of these two components.

paramter	constant or equation	units
Pmemb	between 0 and 10	fmolC cell^-1
Penz	=10-Pmemb

Light2	X axis from 0 to 2000
potential-output-Pmemb	=Pmemb*TANH(Light2/100)	productivity
potential-output-Penz	=1 * Penz

actual output	=MIN(of these two)

Your graph should look like this:

As you change Pmemb between 0 and 10,the curve will change. You are supposed to undestand what gives the best output at each light.

Question 3: What is the maximum rate of photosythesis you can get under any condition?
Question 4: What is the maxiumum rate of photosynthesis you can get at 100 umol photons m^-2 s^-1? What are the conditions for that?
Question 5: What happens if you have an optimal setting for light, Pmemb and Penz, and then you decrease the light in half?
Question 6: Describe a set of instructions that tells you how to adjust the amount of Pmemb and Penz. Use If - Then statements.

Meta-question: Why can't the cell have both high Pmax and a low Ik?

It would be best if you did this on your own, but if you get stuck; I have the Excel file here.

simulation2.xls