Friday, July 13, 2012

STPM Biology - chapter 4(old syllabus) chapter 6 (new syllabus): Revision essay question 4


4.Explain the process that occurs in Calvin Cycle in plants. [10]

Answer:

-Occurs in stroma of chloroplast
-Does not require sunlight
-RuBP fixes CO2 to form unstable 6C compound
-The fixation is catalysed by RuBP carboxylase -This unstable compound split immediately into 3PG     - 3PG is then phosphorylated into 1,3-BPG
-ATP is used

-Reduction of 1,3-BPG to G3P by NADPH
-To produce 1 molecule of G3P, 3 molecules of CO2 are required

-3 molecules of CO2 will produce 6 molecules of G3P

-Whereby only 1 molecule of G3P will be used to produce sugar

-While the other 5 molecules remain in Calvin cycle-Rearrangement of the 3 carbon G3P producing RuBP and can be used to fix with CO2 again catalysed by RuBP carboxylase

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