CSS Paper Botany 2013 MCQs

The operculum is the lid-like structure of the moss capsule. In many species, it is composed of several layers of thin-walled cells, typically numbering three to four, which help in the dehiscence process when the capsule matures.

Polytrichum plants exhibit differentiation in their leaf structures. While the upper leaves are typically green and photosynthetic, the leaves situated on the lower portion of the stem often become scale-like and turn brown as they age or transition into protective structures. This color change is associated with the loss of chlorophyll and the maturation of the lower stem tissues.

In the mature gametophore of Funaria, the stem bears numerous small, spirally arranged leaves. The leaves located on the upper portion of the erect branches are typically larger and more developed, often referred to as foliage leaves. These leaves are primarily responsible for photosynthesis and are arranged to maximize light absorption for the plant, which is essential for its survival and reproductive development.

The columella is a central, sterile column of tissue that runs through the theca of the moss capsule. It is surrounded by the spore sac. The columella provides structural support to the capsule and is involved in the conduction of water and nutrients to the developing spores, ensuring their proper maturation before release.

During archegonium development, the archegonial initial cell undergoes a transverse division to form an outer cell (also called the cover cell) and a basal cell. The outer cell eventually gives rise to the neck canal cells and the venter, while the basal cell forms the stalk.

Sphagnum moss is well-known for its antiseptic properties. Due to the presence of phenolic compounds and its acidic nature, it has been used historically as a dressing for wounds to prevent infection and absorb fluids.

Polytrichum is a genus of mosses belonging to the division Bryophyta. While Bryopsida is a class and Polytrichaceae is a family, the overarching taxonomic division for all mosses, including Polytrichum, is Bryophyta.

Porella is a well-known genus of leafy liverworts belonging to the class Hepaticopsida. While Marchantia is also a liverwort, Porella is specifically recognized for its distinct leafy thallus structure. The other options provided are either incorrect classifications or general botanical terms rather than specific genera of liverworts.

Following fertilization, the zygote undergoes a transverse division. The upper cell formed by this division is termed the epibasal cell, while the lower cell is the hypobasal cell. The epibasal cell typically contributes to the development of the main body of the sporophyte, including the capsule, while the hypobasal cell often forms the foot and seta, establishing the polarity of the developing embryo.

The protonema of a moss differentiates into two types of filaments: chloronema, which are green and photosynthetic, and caulonema, which are brown, branched, and give rise to the leafy gametophore buds.