Tutorial #4 -- Photosynthesis: the basis of life
1. Basics of photosynthesis:
a. Review the anatomy of the leaf and the cellular locations and organelles involved in photosynthesis.
A leaf consists of waxy cuticle layer with stoma surrounded by guard cells, xylem vascular bundle, and a mesophyll. The chloroplast is located within the mesophyll cells. The stroma and thylakoids are located inside the chloroplast. The thylakoids contain chlorophyll. The organelles that participate in photosynthesis are chloroplast, thylakoids and chlorophyll in photosystem I and II.
b. Describe and explain the role ...view middle of the document...
This phase takes hydrogen from the water, releases oxygen, changes light energy into chemical energy, and makes glucose:
2H2O 4H+ + 4e- + O2
The light independent reaction occurs during nighttime. It uses the oxygen and glucose made in the first phase to create and release CO2. The length of this process depends on how much energy was stored in the plant during the daytime:
CO2 + 4H+ + 4e- [CH2O] + H2O
e. Explain why Rubisco is possibly the most important protein on the planet.
The Rubulose bisphosphate carboxylase is an enzyme that fix’s the carbon in carbon dioxide. It produces two molecules, which produces 1 molecule of glucose in the Calvin cycle. Therefore, Rubisco is important because carbon fixation is necessary for the production of glucose.
2. Explain why a huge meteorite colliding with the earth could lead to changes in CO2 in the atmosphere. Discuss how this might ultimately affect the earth’s atmosphere, and consequently, life on earth.
A huge meteorite colliding with the earth would increase the level of CO2 in the atmosphere. The excess about of CO2 would block the loss of radiation heat and would cause the temperature on earth to increase. This would cause the greenhouse effect. Life on earth would suffer because the rise in temperature would cause the polar ice caps to melt and submerge land and civilization underwater.
3. You have a portable leaf chamber and sensors attached to the LabPro interface and can measure the photosynthetic rate of leaves on trees in a forest at different parts of the tree; high up, in the middle, and on lower branches. Below are the ‘raw’ data from your measurements. Assume all leaves completely cover a 9 cm2 leaf chamber.
a. Find the CO2 exchange (µmole/m2/s) for each species at each level in the trees. If you present this to the class, prepare a clear explanation of how you arrived at your answers.
∆CO2 = 353ppm – 312ppm = 41ppm
CO2 exchange = [41/ (22.413((273+25)/273))] = 1.67µmoles/L
1.67 µmoles/L x (0.51/60sec) x (9 cm2) x (1000cm2 /1 m2) = 15.46 µmoles/ m2/ sec
∆CO2 = 345ppm – 320ppm = 25ppm
CO2 exchange = [25/ (22.413((273+23)/273))] = 1.02µmoles/L
1.02 µmoles/L x (0.51/60sec) x (9 cm2) x (1000cm2 /1 m2) = 9.44 µmoles/ m2/ sec
∆CO2 = 341ppm – 326ppm = 15ppm
CO2 exchange = [15/ (22.413((273+21)/273))] = 0.621µmoles/L
0.62 µmoles/L x (0.51/60sec) x (9 cm2) x (1000cm2 /1 m2) = 5.75 µmoles/ m2/ sec
∆CO2 = 353ppm – 319ppm = 34ppm
CO2 exchange = [34/ (22.413((273+25)/273))] = 1.39µmoles/L
1.39 µmoles/L x (0.51/60sec) x (9 cm2) x (1000cm2 /1 m2) = 12.87 µmoles/ m2/ sec
∆CO2 = 345ppm – 323ppm = 22ppm
CO2 exchange = [22/ (22.413((273+23)/273))] = 0.905µmoles/L
0.905 µmoles/L x (0.51/60sec) x (9 cm2) x (1000cm2 /1 m2) = 8.37 µmoles/ m2/ sec
∆CO2 = 341ppm – 320ppm = 11ppm
CO2 exchange = [11/ (22.413((273+21)/273))] = 0.455µmoles/L
0.455 µmoles/L x...