Assertion: Plants possessing C4&hyphen;pathway of carbon fixation have a higher net primary productivity than the C3&hyphen;pathway possessing plants. Reason: For each unit weight of fixed carbon, C4&hyphen;pathway possessing plants require less water than the C3&hyphen;pathway possessing plants.

Question

Assertion: Plants possessing C4&hyphen;pathway of carbon fixation have a higher net primary productivity than the C3&hyphen;pathway possessing plants. Reason: For each unit weight of fixed carbon, C4&hyphen;pathway possessing plants require less water than the C3&hyphen;pathway possessing plants. (A) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion (B) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion (C) If Assertion is true but the Reason is false (D) If both Assertion and Reason are false

Tardigrade Admin · Accepted Answer

C3 plants exclusively fix CO2 via the Calvin-Benson pathway. The leaf cells of C4 plants possess two types of chloroplast, bundle sheath cells and mesophyll cells. The mesophyll cells of C4 plants exhibit high activity of phosphoenolpyruvate (PEP) carboxylase, which catalyses the fixation of CO2 with PEP to form oxaloacetic acid. The bundle sheath cells exhibit high RuBP carboxylase and the other enzymes of the CalvinBenson cycle. C4 plants are highly productive photosynthetically in view of the low affinity of RuBP carboxylase for its substrate. But CO2 is concentrated as C4 acids due to the activity of the PEP carboxylase, which in effect maintains high pool levels of CO2 . C4 plants is related to very high light-harvesting saturation points. C4 plants exhibit low rates of photorespiration only in bundle sheath cells. C4 plants are adapted to high temperature. C4 plants show better utilisation of available water but it cannot be the cause of its higher productivity.

Q. Assertion: Plants possessing C4‐pathway of carbon fixation have a higher net primary productivity than the C3‐pathway possessing plants. Reason: For each unit weight of fixed carbon, C4‐pathway possessing plants require less water than the C3‐pathway possessing plants.

If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion

If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion

If Assertion is true but the Reason is false

If both Assertion and Reason are false

Q. Assertion: Plants possessing C₄‐pathway of carbon fixation have a higher net primary productivity than the C₃‐pathway possessing plants.
Reason: For each unit weight of fixed carbon, C₄‐pathway possessing plants require less water than the C₃‐pathway possessing plants.