Botany and Plant Science

Peristome teeth are specialized structures found at the mouth of the moss capsule. They are hygroscopic, meaning they bend outwards or inwards in response to changes in humidity, which actively aids in the gradual dispersal of spores. Other parts like the columella provide support, while the operculum acts as a lid.

The columella is a central, sterile column of parenchymatous tissue found in the capsule of mosses. It provides structural support to the surrounding spore sac and helps in the conduction of water and nutrients to the developing spores.

The gametophytic phase of Riccia begins with the haploid spore, which germinates to form the vegetative thallus. This thallus produces male and female gametes in the antheridia and archegonia, and their fusion (fertilization) results in the formation of a diploid zygote, which marks the end of the gametophytic phase.

Polytrichum is a genus of mosses, and its sporogonium (sporophyte) is differentiated into three distinct regions: the foot (which anchors it to the gametophyte and absorbs nutrients), the seta (a long stalk), and the capsule (where spores are produced). This tripartite division is characteristic of advanced bryophyte sporophytes.

In Riccia, the sporophyte is extremely simple, consisting only of a capsule that remains permanently embedded within the tissue of the gametophytic thallus. Because it lacks any specialized dehiscence mechanism like elaters or peristome teeth, the spores are only released when the surrounding thallus and outer capsule wall decay and decompose.

In mosses like Funaria, stomata are present exclusively on the apophysis, which is the sterile basal region of the capsule. These stomata are considered primitive because they often consist of a single ring-like guard cell with a central pore, rather than two distinct kidney-shaped guard cells.

Chlorenchyma is a specialized parenchymatous tissue containing chloroplasts, responsible for photosynthesis. In the sporophyte of a moss, particularly in the outer layers of the capsule wall and the apophysis region, chlorenchyma is well-developed, allowing the sporophyte to manufacture some of its own food. Chlorella is a unicellular alga, Aspergillus is a non-photosynthetic fungus, and pollen tubes lack chlorenchyma.

Mosses are non-vascular plants, meaning they lack true vascular tissues like xylem and phloem. Instead, conduction of water and nutrients is carried out by specialized elongated parenchymatous cells called hydroids (for water) and leptoids (for food), which are structurally simple parenchyma.

Riccia is a bryophyte, a group in which the dominant, independent phase of the life cycle is the gametophyte, which produces haploid gametes. In Lycopodium, Equisetum, and Pinus, the dominant plant body is the sporophyte.

The leaf-like structures of moss gametophytes are photosynthetic and contain chloroplasts, but they lack true stomata. Stomata are present on the sporophyte capsule rather than the gametophytic leaves.

Polytrichum is a bryophyte (moss) which exhibits a dominant, independent gametophytic phase alternated by a multicellular sporophyte that is physically dependent on the gametophyte.

In Hepaticopsida (liverworts like Marchantia and Riccia), the rhizoids are unicellular and are of two distinct types: smooth-walled and tuberculate (pegged).

Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because the sporophyte in mosses is more elaborate than in liverworts. Statement (v) is incorrect because Pinus is monoecious, while Marchantia is dioecious.

Plant body of bryophyte is differentiated than that of algae and it is thallus like and prostate and effect. The main plant body is haploid and is known as gametophyte. There is a multicellular body which is known as sporophyte which is not free living and is attached to the gametophyte and derives nourishment from it.

Sperm of mosses are biflagellated, ie., it has two flagella that aid in propulsion. Since sperm must swim to the archegonium, fertilisation cannot occur without water.