Question

The characteristics of C${}_4$ plants are

(a) Kranz anatomy

(b) First product is oxaloacetic acid

(c) Carboxylating enzymes are PEP carboxylase and RuBisCO

• A. a and b but not c
• B. b and c and not a
• C. a and c but not b
• D. All a, b and c

Answer 1

Answer: (D)

All a, b and c

Plants such as sugarcane and sorghum fix atmospheric carbon dioxide with the carboxylation of phosphoenol pyruvic acid to produce oxaloacetic acid (a C${}_4$ acid) in the presence of phosphoenolpyruvate carboxylase (PEP carboxylase). Such plants are called C${}_4$ plants.

C${}_4$ plants have Kranz leaf anatomy. The vascular bundles, in these leaves, are surrounded by a layer of bundle sheath cells that contain a large number of chloroplasts.

Malic acid (Product of C${}_4$ cycle) transport from mesophyll cell to bundle sheath where C${}_3$ cycle starts which require RuBisco enzyme.

So, the correct answer is 'All a,b, and c'.