Question

Complementary cells are formed by the activity of
A. Vascular cambium
B. Interfascicular cambium
C. Phellogen
D. Intra-fascicular cambium

Answer 1

The complementary cells are a mass of cells in plants that are formed from the cork cambium at the position of the lenticels. It is a group of loosely arranged cells that help in gaseous exchange through the cork.

Complete step by step answer: The complementary cells are formed from the cork cambium /phellogen at the position of the lenticels. It is a group of loosely arranged cells that aid in gaseous exchange through the cork. As the lenticels formation starts, the parenchyma cells found near the substomatal cavity lose their chlorophyll content and start dividing irregularly in different plants giving rise to a mass of colourless, rounded, thin-walled, loosely arranged cells, called complementary cells.
Sometimes complementary cells produced by phellogen towards the outside instead of producing cork cells. As the complementary cells increase in number, the pressure is exerted against the epidermis and it ruptures. Outermost cells gradually become dead and may be replaced by cork cells. Among the given options:
A. The vascular cambium is the main growth tissue in the stems and roots of many plants, specifically in dicots such as buttercups and oak trees, gymnosperms such as pine trees, as well as in certain vascular plants. It produces secondary xylem inwards, towards the pith, and secondary phloem outwards, towards the bark.
B. The interfascicular cambium originates between the vascular bundles. These possess secondary meristem and develop from parenchymatous cells of medullary rays. Hence, they cannot produce secondary tissues. A ring of meristematic tissue formed in the cortex of dicotyledonous stem during secondary growth is called phellogen or cork cambium. It produces cork towards the periphery and secondary cortex towards the inner side
C. Intrafascicular cambium is a secondary meristem. It develops from the parenchymatous cells of medullary rays. It is located between two consecutive vascular bundles. During secondary growth, its derivatives are secondary phloem, secondary xylem and conjunctive tissue.
Hence, the correct answer is option C.

Note: The vascular cambium is responsible for increasing the diameter of stems and roots and for forming woody tissue. The cork cambium produces the bark. Monocots do not have a vascular cambium, even though some of them, such as palms and the Joshua tree, exhibit secondary growth. Instead, they have a thickening meristem that produces secondary ground tissue.