Question

Which of the following is a C4 plant?
A. Maize
B. Atriplex
C. Sugarcane
D. All of the above

Answer 1

Hint: The plants in which oxaloacetic acid (OAA) is the first stable product after the fixation of carbon dioxide is called C4 plants. OAA is the four carbon compounds and hence, the plants are called C4 plants. The C4 plants have a special type of anatomy in their leaves. It is called Kranz anatomy.

Complete answer
The plants that grow in hot and dry environmental conditions use the C4 pathway. C4 pathway is seen in grasses such as sugarcane, maize etc. Various important crops such as sorghum, Atriplex, millets that grow in savanna regions also undergo the C4 pathway.
The leaves of C4 plants shows the following anatomical features-
-The vascular bundles of C4 plants are surrounded by several layers of bundle sheath cells. -The chloroplasts of the bundle sheath cells are very large. There are no intercellular spaces between the bundle sheath cells.
-The mesophyll cells have chloroplasts that are smaller in size.
-Two enzymes are involved in the C4 pathway- RuBisCO and PEPCase enzyme. RuBisCO enzyme is present in bundle sheath cells while PEPCase enzyme is present in mesophyll cells.

The C4 pathway provides advantage to plants in the following ways-
-C4 plants are more tolerant to high temperature
-They use water more efficiently than other plants
-In C4 plants, no photorespiration takes place which is a waste phenomenon
-High carbon dioxide fixation increases the productivity of these plants.

Thus the answer of the above question is option (D) all of the above.

Note: As the C4 pathway was discovered by Davidson Hatch and Charles Roger Slack, it is also called Hatch and Slack pathway. The C4 pathway provides many advantages to the plant over C3 plants. It increases the concentration of carbon dioxide in the cells in which sugars are formed. Hence, the productivity of C4 plants is higher than C3 plants.