Page 46 - Q & A STPM 2022 Biology
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Biology STPM Answers
– The oxygen is a final – Glycerate-3-phosphate is
electron acceptor that phosphorylated by ATP
combines with hydrogen to become glycerate-1,
ion/H to form water. 3-diphosphate.
+
– H ions / protons pumped – The glycerate-1,
+
across the membrane into 3-diphosphate is then
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the intermembrane space. reduced by NADPH
– There is a build-up and is converted into
of a proton gradient/ glyceraldehyde-3-phosphate
electrochemical gradient/ (PGAL, triose phosphate),
proton motive force. a 3-carbon sugar.
– The protons are pumped – Some glyceraldehyde-3-
1
back through the ATP phosphate ( PGAL) is
6
synthase. used to assimilate organic
– The energy generated is molecules such as glucose,
used to synthesis ATP from sucrose, starch, proteins
ADP+P. i
– Therefore, for 1 molecule of and lipids.
NADH, 3 ATP while for 1 – The rest of the 5
molecule of FADH, 2 ATP glyceraldehyde ( PGAL)
6
are produced. is converted in a series
19. (a) – Calvin cycle occurs in the of complex reactions
stroma of the chloroplast. to regenerate ribulose
– It involves a series of bisphosphate.
reactions that results in the – The processs requires ATP
reduction of carbon dioxide and a series of accessory
into carbohydrate. enzymes.
– NADPH and ATP, products
of the light-dependent (b) – In C plants, ribulose
3
reaction provides the bisphosphate (RuBP)
reducing power and energy combines with carbon
required in the reactions. dioxide while in C plants
4
– Carbon dioxide from the the carbon dioxide acceptor
atmosphere combines is phosphoenol-pyruvate
with ribulose bisphosphate (PEP).
(RuBP), a 5-carbon – In C plants, this reaction
3
compound to form an is catalysed by ribulose
unstable 6-carbon sugar. bisphosphate carboxylase
– The enzyme involved in (RuBisCo) which in
this reaction is Ribulose C plants, the reaction
4
bisphosphate carboxylase between PEP and carbon
(RuBisCo). dioxide is catalysed by PEP
– The six-carbon compound carboxylase.
immediately splits into two – In C plants, the first
3
molecules of glycerate-3- product of carbon dioxide
phosphate (GP), a 3-carbon fixation is glycerate-3-
compound. phosphate, a 3-carbon
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Jawapan.indd 535 11/2/21 9:13 AM
