Name _______________________
BCH/PLS/PPA 609 3rd section exam May 7, 2009
(90 points)
Each question is worth a total of 18 points.
1. Describe the nitrogen cycle including nitrification and denitrification.
1
Name _______________________
2. Give all the steps of the Calvin-Benson Cycle starting with the fixation of ribulose-bisphosphate (RuBP) with 6 CO2 molecules to the generation of glucose and regeneration of
RuBP. Include all substrates and products including source(s) of energy and reduction
(electrons). You will get full credit if you have all the structures correct or mostly correct.
You can get partial credit for most of the cycle and some compound names instead of
structures.
2
Name _______________________
3. Describe biological nitrogen fixation from the initial fixation to the export of nitrogenous
compounds from the nitrogen fixing nodules.
3
Name _______________________
4. Following are all but two main structures of the allene oxide synthase and hydroperoxide
branches of oxylipin biosynthesis. Place these in order of their biosynthesis and give the
structures of the missing two intermediate molecules. Briefly describe what you know about
the biological role of at least two of these molecules in plants.
COOH
O-Glucose
HOC
COOH
O
O
COOH
O
OOH
CH2OH
COOH
COOH
CHO
O
COOH
HOC
COOH
O
COOH
COOCH3
O
You need not redraw these, you only need to draw the missing 2 intermediates. You might want
to give these numbers and put the numbers in a pathway such as:
1
2
3 etc.
4
Name _______________________
5. Consider that you are hired for a new job after finishing your Ph.D. and you are given the
task of increasing the oil (triacylglycerol, TAG) content of soybean seeds from 20 to 30% of
seed dry weight without changing the protein levels. Normal soybean seeds are 20% TAG,
40% protein, 10% oligosaccharides, 5% minerals (especially phosphate sequestered as a
sugar phosphate ester known as phytate, inositol-hexa-phosphate). The remainder is other
carbohydrates which does not include starch or fructans. The hydrocarbon that accumulates
in soybean seeds like other plant seeds is delivered to the developing seeds in the form of
sucrose and amino acids via the phloem. Outline what metabolic steps you would change to
achieve the goal of 30% TAG + 40% protein and how they might be changed.
5