Question

Which meristem helps in increasing girth?
A. Lateral meristem/Cambium
B. Intercalary meristem
C. Primary meristem
D. Apical meristem

Answer 1

Hint: Meristem is a tissue type that is present in plants. It consists of undifferentiated cells that are capable of cell division (meristematic cells). Meristem cells can expand into all the other tissues and organs that are present in plants.

Complete Answer:
Meristem, a cell area capable of division and growth of plants. Meristems are classified as apical (located at the root and shoot tips), lateral (in the vascular and cork cambia) and intercalary (in the vascular and cork cambia) by their position in the plant (in the internodes of the stem regions between the places where the leaves attach and the leaf bases, in particular some monocotyledons, such as grasses).

Apical meristems give rise to the primary body of the plant and are responsible for the roots and shoots being extended. As they are responsible for secondary growth, or increase in stem girth and thickness, lateral meristems are known as secondary meristems. In damaged tissues, meristems form anew from other cells and are responsible for wound healing. Due to the infinite division of meristematic zones, plants continue to expand throughout their entire life cycle, unlike most species.

Typically, meristematic cells are small and near spherical. They have a large cytoplasm and very few tiny vacuoles (watery saclike enclosures). The meristem is preserved as a continuous source of new cells by some of these cells known as initials, and may undergo mitosis (cell division) several times before differentiating into the particular cells needed for that plant body area.

In lines known as primary meristems of partially differentiated tissues, the cells arising from the apical meristem are arranged. The protoderm that becomes the epidermis; the soil meristem that forms the parenchyma, collenchyma, and sclerenchyma cells of the soil tissues; and the procambium that becomes the vascular tissues (xylem and phloem).

The correct Answer is option (A) Lateral meristem/cambium.

Note: The periderm, which is identical to the protoderm, gives rise to the cork cambium. While a plant's primary epidermis growth is created by the protoderm, the epidermis replaces the epidermis to produce bark. The bark, through a waxy substance called suberin, acts as a protection for the plant, barring it from physical harm and preventing water loss.