CSS Paper Botany 2010 MCQs

In the development of the male gametophyte of certain primitive vascular plants, the antheridial cell undergoes a series of divisions. Following these specific mitotic divisions, a total of 12 cells are formed, which eventually contribute to the structure of the mature antheridium and the production of male gametes.

The term 'stachysporous' refers to the condition in plants where sporangia are associated with specialized leaves or sporophylls, often organized into a strobilus or cone. In Selaginella, the sporangia are located in the axils of these sporophylls. While the term is sometimes debated in strict morphological contexts, it is traditionally used to describe this arrangement in the Selaginellaceae family.

The sporogenous tissue within a sporangium is derived from archesporial cells. These cells undergo divisions to eventually differentiate into spore mother cells, which then undergo meiosis to produce spores.

In the development of the antheridium in certain pteridophytes, the primary androgonial cells undergo repeated mitotic divisions. These divisions are synchronized and typically result in a specific range of androcytes, which eventually metamorphose into biflagellate or multiflagellate antherozoids. The range of 128 to 256 cells is a standard observation in the developmental biology of these specific plant groups.

Selaginella is classified under the class Lycopsida within the division Lycopodiophyta. This group is characterized by having microphyllous leaves and sporangia typically associated with sporophylls. While 'Selaginellales' is the order and 'Selaginellaceae' is the family, 'Lycopsida' represents the broader taxonomic class to which this genus is assigned in standard botanical classification systems.

The reproductive structures in Lycopsida, known as strobili, are often referred to as club-shaped, spike-like, or simply cones. These terms are frequently used interchangeably in botanical literature to describe the compact arrangement of sporophylls bearing sporangia at the tips of branches.

Taxonomically, the genus Selaginella is classified under the order Selaginellales. This order is part of the class Lycopsida. It is important to distinguish between the order (Selaginellales) and the family (Selaginellaceae) to maintain accurate botanical classification.

The stem of Selaginella is covered by a single layer of cells known as the epidermis. This layer is typically composed of thin-walled cells and lacks stomata in many species, serving as the primary protective barrier for the underlying cortical tissues.

A ligule is a characteristic membranous outgrowth found at the base of the leaves in the genus Selaginella. It is a diagnostic feature used to distinguish ligulate lycopsids from other groups, playing a role in water absorption and protection of the leaf primordia.

During the initial stages of male gametophyte development in various pteridophytes, the microspore undergoes division to produce a smaller prothallial cell and a larger antheridial cell. The antheridial cell subsequently undergoes further divisions to eventually form the antheridium, which produces the male gametes. This process is a characteristic feature of the gametophytic generation in these vascular cryptogams.