Question

Compare the plants showing C3 and C4 pathways. Using the given table format fill in the correct information. $\begin{array}{cccc}\text{Characteristics}& \text{C3 Plant}& \text{C4 Plant}& \text{Choose from}\\ \text{Cell type in which the}& & & \text{Mesophyll/}\\ \text{Calvin cycle takes place}& & & \text{Bundle sheath/ both}\\ \text{Cell type in which the}& & & \text{Mesophyll/}\\ \text{initial carboxylation}& & & \text{Bundle sheath/ both}\\ \text{reaction occurs}& & & \\ \text{How many cell types}& & & \text{Two: Bundle sheath}\\ \text{does the leaf have}& & & \text{and mesophyll One:}\\ \text{that fix}C{O}_2& & & \text{Mesophyll Three:}\\ & & & \text{Bundle sheath, palisade,}\\ & & & \text{spongy mesophyll}\\ \text{Which is the primary}& & & \text{RuBP/PEP/PGA}\\ C{O}_2\text{acceptor}& & & \\ \text{No.of carbons in the}& & & \text{5/4/3}\\ \text{primary}C{O}_2\text{acceptor}& & & \\ \text{Which is the primary}& & & \text{PGA/OAA/RuBP/PEP}\\ \text{primary}C{O}_2\text{fixation}& & & \\ \text{product}& & & \\ \text{No. of carbons in the}& & & \text{3/4/5}\\ \text{primary}C{O}_2\text{fixation product}& & & \\ \text{Does the plant have}& & & \text{Yes/No/Not always}\\ \text{RuBisCO}& & & \\ \text{Does the plant have}& & & \text{Yes/No/Not always}\\ \text{PEP Case}& & & \\ \text{Which cells in the}& & & \text{Mesophyll/ Bundle}\\ \text{plant have RuBisCO}& & & \text{sheath/ None}\\ C{O}_2\text{fixation rate}& & & \text{Low/High/Medium}\\ \text{under high light}& & & \\ \text{conditions}& & & \\ \text{Whether photorespiration}& & & \text{High/ negligible/}\\ \text{is present at low light}& & & \text{sometimes}\\ \text{intensities}& & & \\ \text{Whether photorespiration}& & & \text{High/ negligible/}\\ \text{is present at high light}& & & \text{sometimes}\\ \text{intensities}& & & \\ \text{Whether photorespiration}& & & \text{High/ negligible/}\\ \text{is present at low}C{O}_2& & & \text{sometimes}\\ \text{concentrations}& & & \\ \text{Whether photorespiration}& & & \text{High/ negligible/}\\ \text{is present at high}C{O}_2& & & \text{sometimes}\\ \text{concentrations}& & & \\ \text{Temperature optimum}& & & {\text{30-40}}^{0}C,{\text{20-25}}^{0}C\\ & & & {\text{above 40}}^{0}C\\ \text{Examples}& & & \end{array}$

Answer 1

Part 1: Introduction
The plants which use C3 carbon fixation pathway and the first product of carbon dioxide fixation is a 3-carbon organic compound, 3-phosphoglycerate, are termed as C3 plants. The plants in which the first product of carbon dioxide fixation is a 4-carbon organic compound, oxaloacetate, are termed as C4 plants.

Part 2: Anatomy of leaf
The arrangement of mesophyll and bundle sheath cells in the leaf of C4 plants is different from C3 plants. The parenchymatous cell which is a type of ground tissue present in the leaf is called mesophyll. The cells surrounding the vascular bundles are called the bundle sheath. In the C4 plant these mesophyll cells are clustered around the bundle sheath cells and form a shape which is similar to the wreath. This arrangement seen in the leaf of C4 plants is called Kranz anatomy. In C3 plants the mesophyll cells are not clustered and they do not exhibit Kranz anatomy . In C3 plants chloroplast are present only in the mesophyll cells. In C4 plants chloroplasts are present in bundle sheath as well as mesophyll cells.

Part 3: First stable product
In the C3 pathway the first stable product of this pathway is 3-Phosphoglycerate. In the C4 pathway the first stable product is OAA (oxaloacetic acid).

Part 4: Primary $C{O}_2$ acceptor
In the C3 pathway a five-carbon compound called RuBP is the primary $C{O}_2$ acceptor. Whereas in the C4 pathway it is a three carbon compound called PEP.

Part 5: Tabular difference $\begin{array}{cccc}\text{Characteristics}& \text{C3 Plant}& \text{C4 Plant}& \text{Choose from}\\ \text{Cell type in which the}& \text{Mesophyll}& \text{Bundle sheath}& \text{Mesophyll/}\\ \text{Calvin cycle takes place}& & & \text{Bundle sheath/ both}\\ \text{Cell type in which the}& \text{Mesophyll}& \text{Mesophyll}& \text{Mesophyll/}\\ \text{initial carboxylation}& & & \text{Bundle sheath/ both}\\ \text{reaction occurs}& & & \\ \text{How many cell types}& \text{One: mesophyll}& \text{Two: Bundle sheath}& \text{Two: Bundle sheath}\\ \text{does the leaf have}& & & \text{and mesophyll One:}\\ \text{that fix}C{O}_2& & & \text{Mesophyll Three:}\\ & & & \text{Bundle sheath, palisade,}\\ & & & \text{spongy mesophyll}\\ \text{Which is the primary}& \text{RuBP}& \text{PEP}& \text{RuBP/PEP/PGA}\\ C{O}_2\text{acceptor}& & & \\ \text{No.of carbons in the}& \text{5}& \text{3}& \text{5/4/3}\\ \text{primary}C{O}_2\text{acceptor}& & & \\ \text{Which is the primary}& \text{PGA}& \text{OAA}& \text{PGA/OAA/RuBP/PEP}\\ \text{primary}C{O}_2\text{fixation}& & & \\ \text{product}& & & \\ \text{No. of carbons in the}& \text{3}& \text{4}& \text{3/4/5}\\ \text{primary}C{O}_2\text{fixation product}& & & \\ \text{Does the plant have}& \text{Yes}& \text{Yes}& \text{Yes/No/Not always}\\ \text{RuBisCO}& & & \\ \text{Does the plant have}& \text{Yes}& \text{Yes}& \text{Yes/No/Not always}\\ \text{PEP Case}& & & \\ \text{Which cells in the}& \text{Mesophyll}& \text{Bundle sheath}& \text{Mesophyll/ Bundle}\\ \text{plant have RuBisCO}& & & \text{sheath/ None}\\ C{O}_2\text{fixation rate}& \text{Medium}& \text{High}& \text{Low/High/Medium}\\ \text{under high light}& & & \\ \text{conditions}& & & \\ \text{Whether photorespiration}& \text{Negligible}& \text{Negligible}& \text{High/ negligible/}\\ \text{is present at low light}& & & \text{sometimes}\\ \text{intensities}& & & \\ \text{Whether photorespiration}& \text{High}& \text{Negligible}& \text{High/ negligible/}\\ \text{is present at high light}& & & \text{sometimes}\\ \text{intensities}& & & \\ \text{Whether photorespiration}& \text{High}& \text{Negligible}& \text{High/ negligible/}\\ \text{is present at low}C{O}_2& & & \text{sometimes}\\ \text{concentrations}& & & \\ \text{Whether photorespiration}& \text{Negligible}& \text{Negligible}& \text{High/ negligible/}\\ \text{is present at high}C{O}_2& & & \text{sometimes}\\ \text{concentrations}& & & \\ \text{Temperature optimum}& {\text{20-25}}^{0}C& {\text{30-40}}^{0}C& {\text{30-40}}^{0}C,{\text{20-25}}^{0}C\\ & & & {\text{above 40}}^{0}C\\ \text{Examples}& \text{Wheat, rice}& \text{Maize, sugarcane}& \end{array}$