CSS Paper Botany 2013 MCQs

Rhizoids are hair-like extensions found in bryophytes and some pteridophytes. They function similarly to roots by anchoring the plant to the substrate and facilitating the absorption of water and essential minerals from the environment, although they lack true vascular tissue.

The peristome is a specialized structure located at the mouth of the moss capsule. It consists of teeth-like appendages that respond to changes in humidity. By opening and closing, these peristome teeth act as a regulatory mechanism, ensuring that spores are released gradually and only under favorable environmental conditions, which increases the chances of successful dispersal and germination.

Funaria is a well-known genus of mosses that belongs to the order Funariales. This order is characterized by specific features of the sporophyte, such as the structure of the capsule and the peristome teeth. It is placed within the class Bryopsida, which contains the majority of true mosses.

As the sporophyte matures, the calyptra, which is derived from the venter of the archegonium, is pushed upward. Eventually, it ruptures and remains as a cap-like structure covering the apex of the capsule before it is shed.

The annulus is a specialized ring of thin-walled cells located at the junction between the operculum and the theca of the moss capsule. These cells are hygroscopic and play a critical role in the dehiscence process, as they help in the detachment of the operculum, thereby allowing the spores to be released from the capsule.

In the stems of certain mosses, conducting tissues are differentiated into hydroids (for water transport) and leptoids. Leptoids are elongated, living cells that resemble the sieve elements of vascular plants and are responsible for the translocation of organic nutrients throughout the moss gametophyte.

The female sex organ in bryophytes is called the archegonium (often spelled archigonia in plural). It is a flask-shaped structure that protects the developing egg cell. The male sex organ, by contrast, is known as the antheridium, which produces motile sperm cells.

Paraphyses are sterile, hair-like structures found interspersed among the sex organs in mosses. They help retain moisture around the archegonia and antheridia through capillary action. This moisture is crucial for protecting the reproductive organs from desiccation and for providing the medium through which motile sperm can swim to reach the egg.

Stereids are specialized, elongated, thick-walled cells found in the central strand of the moss stem. They provide mechanical support and structural integrity to the gametophyte, functioning similarly to sclerenchyma in higher plants.

The sporogenous tissue, which gives rise to spore mother cells through meiosis, is commonly referred to as the archesporium. This tissue is derived from the endothecium in many mosses and is essential for the production of haploid spores.