Question

______________ is an example of a secondary meristem.
A. Xylem
B. Phloem
C. Phellem
D. Cork cambium

Answer 1

Hint:- In plants, the process of growth is a continuous process but some cells become differentiated and they cannot further divide. The plants also bear some types of undifferentiated cells that possess the ability to divide. These types of cells are known as meristem cells and they are able to continue cell division. Meristem or the meristematic tissues are made up of the meristematic cells which are able to divide continuously.

Complete step-by-step solution:-
The meristematic cells are the cells which have not lost the ability to divide or are undifferentiated or incompletely differentiated and are continued with the process of cell division. They are totipotent in nature which means that they are able to develop into all kinds of tissues and organs that are needed by the plant.
The main function of the meristematic cells or tissues is division of the cells that are needed for expansion, differentiation, formation of new organs as well as providing and maintaining the basic structure of the plant. The cells of the meristematic tissues are densely packed with little or no spaces between them. The cell wall is thin with a very thin primary cell wall. On the basis of the region of presence, meristem in plants are divided into three types which are primary or apical meristem, lateral or secondary meristem and intercalary meristem.
The lateral meristem is also known as the secondary meristem and it is found along the lateral sides of the plants especially in the stems. It surrounds the established stem of the plant and helps it to grow laterally and causes the plant to grow and increase in diameter. It is divided into two types which are the vascular cambium and the cork cambium.
The secondary xylem and secondary phloem is formed by the vascular cambium. It gives rise to the woods in plants. Cork cambium gives rise to the periderm and it replaces the epidermis. It occurs as a part of the epidermis and is responsible for secondary growth. The cells that grow towards the inner side are known as phelloderm and those types of cells which grow towards the outside are known as phellem. Phellem is also known as cork. It is dead at maturity and is an air-filled protective tissue which is present on the outside.
The xylem and phloem are the important conducting tissues of the plant that are responsible for conduction of water and other important materials. Xylem transfers water and other minerals from the roots to the stems and leaves and phloem transports the food prepared in the leaves to the roots.

Therefore, the correct option is option D.

Note:- The secondary meristem is responsible for secondary growth in plants and it produces secondary tissues in the form of cork cambium. They cause an increase in the diameter or girth of the plant. The cork cambium exists as a part of the epidermis and gives rise to secondary tissues in this region.