Question

Tabulate any four differences between ${ C }_{ 3 }$ and ${ C }_{ 4 }$ plants.

Answer 1

${ C }_{ 3 }$ plants are plants in which the biosynthetic pathway Calvin cycle operates inside the mesophyll cells to fix carbon in order to produce glucose. Whereas in ${ C }_{ 4 }$ plants, the ${ C }_{ 4 }$ cycle occurs which ensures that the Calvin cycle is occurring at its maximum capacity and there is no wastage.

Complete answer:

${ C }_{ 3 }$ Plants	${ C }_{ 4 }$ Plants
The ${ C }_{ 3 }$ pathway or the Calvin cycle takes place in ${ C }_{ 3 }$ plants.	The ${ C }_{ 4 }$ pathway or the Hatch and Slack pathway take place along with the ${ C }_{ 3 }$ pathway in ${ C }_{ 4 }$ plants.
Photorespiration is not prevented in ${ C }_{ 3 }$ plants.	Photorespiration is prevented in these plants due to the ${ C }_{ 4 }$ pathway taking place.
Photorespiration occurs in ${ C }_{ 3 }$ plants because the first carbon fixation enzyme RuBisCO has oxygenase activity along with carboxylase activity and thus oxidizes the carbon compound instead of fixing the carbon.	Photorespiration does not occur in ${ C }_{ 4 }$ plants because the first carbon fixation enzyme PEPcase does not show any oxygenase activity and thus does not oxidize the carbon compound.
The first carbon acceptor in ${ C }_{ 3 }$ plants is Ribulose bis-phosphate (RuBP)	The first carbon acceptor in ${ C }_{ 4 }$ plants is Phosphophenol pyruvate (PEP).

Note: -Photorespiration is the process of conversion of RuBP into phosphoglycerate and phosphoglycolate with the utilization of oxygen.
-It is a wasteful process because there is no synthesis of sugar or ATP, but instead, the already fixed carbon dioxide is released with the utilization of ATP.
-The ${ C }_{ 4 }$ plants do not show photorespiration because the ${ C }_{ 4 }$ cycle increases the concentration of carbon dioxide at the site of the RuBisCO enzyme. This is done to ensure that the RuBisCO enzyme does not perform oxygenase activity.