Difference between C3 and C4 pathway.

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answered Nov 25, 2020 by Maisa (44.0k points)
selected Nov 27, 2020 by Panna01

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S.No.	Characteristics	C₃ Pathway	C₄ Pathway
(i)	Cell type	One (mesophyll)	Two (mesophyll and bundle sheath).
(ii)	Kranz anatomy	Absent in leaves	Present in leaves
(iii)	Chloroplasts type	One type (granal only)	Two types (granal and agranal) Dimorphic
(iv)	CO₂ acceptor	Ribulose 1, 5 bisphosphate (RuBP)	Phosphoenolpyruvate (PEP)
(v)	First CO₂ fixation product	3-PGA (3C compound)	Oxaloacetic acid (4C compound).
(vi)	Carboxylase enzyme	RuBisCO enzyme	PEP carboxylase; RuBisCO
(vii)	CO₂ fixation rate	Low	High
(viii)	O₂ inhibition of photosynthesis	Present	Absent
(ix)	Photorespiration	High	Nil
(x)	Productivity	Low productivity	High productivity
(xi)	CO₂ compensation point	High(25-100μ1 CO₂)	Low(0-10μ1CO₂)
(xii)	Temperature optimum	20 to 25º C (Low temperature)	30 to 45°C (High temperature)
(xiii)	Examples	Rice, wheat and potato etc.	Maize, pearl millet, Amaranthus, grass etc.