Give an account of structure, reproduction and life history of Batrachospermum

It is fresh water red algae and belongs to class Rhodophyceae and normally lives in cool, well aerated clear and shady situations. Plant body is filamentous freely branched and gelatinous in texture. Plant is like a chain of delicate beads. Each bead consists of a whorl of densely branched laterals of limited growth. Main axis consists of single row of elongated cells placed one above the other. From main axis arise branches of unlimited growth. Also node cells give rise to filaments which grow downwards the next node covering the axis cells forming pseudo cortex. Each cell of filament consists of two layered cell wall outer of pectin and inner of cellulose, cells are unimucleaet and contain a large number of parietal chromatophores, each with a single pyrenoid. Growth takes place by an apical cell.

Reproduction: It takes place by sexual method.
Sexual reproduction:

It is advanced oogamous type. Plants may be monoecious and dioecious. Male reproductive organ is antheriduim and female reproductive organ is called carpogonuim.
The antheriduim (Spermatogonuim) is a spherical or oblong unicellular structures which arise at the distal ends of short laterals. They arise in large numbers. Each antheriduim produces a single non-motile spermatuim (male cell) the spermatia are unimucleate and probably have same specific gravity as that of surrounding water. Therefore they remain floating.

The capranguim or procarp consists of a swollen basal portion with an egg and a narrow elongated neck like trichogyne. The caprogonia arise terminally on the laterals. The constricted portion of caprogonuim separating the trichogyne from the basal swollen portion known as plug. The caprogonuim develops at the tip of the caprogonial branch which is usually 3 to 4 celled. The terminal cell of caprogonal branch enlarges and becomes flask shaped. The single nucleus of terminal cell forms the egg.
Fertilization: The spermatia on liberation are carried away by water to trichogyne at the point of contact of spermatia disorganize and the nucleus of the spermatium passes down into carpogonium and fuses with its nucleus. A wall develops at the base of corpogonium and zygote is formed .

Germination of zygote:
The nucleus of diploid zygote increases in size and divides meiotically into two daughter nuclei lying one above the other. One of the nucleus migrates into a lateral protrusion which develops to the side of carpogonium and is cut off by wall and form gonimoblast initial which develop gonimoblast filament.

Comments

Post a Comment

Popular posts from this blog

Compare the anatomy of Bifacial and Isobilateral leaves

BIFACIAL LEAF: It is also called dorsiventral leaf. This leaf is more strongly illuminated on upper surface than on lower surface. This unequal illumination induces a difference in the internal structure between upper and lower sides. Its internal structure shows: (1)        Upper Epidermis This is single layer of cells with thick cuticle which checks excessive evaporation of water from the surface. It does not contains chloroplasts, stomata are also absent. (2)        Lower Epidermis This is also single layer but with a thin cuticle. It bears many stomata, two guard cells of which contain some chloroplast, none are present in the epidermal cells. Internal to each stomata is large cavity called respiratory cavity. Lower epidermis of leaf is meant for exchange of gases (oxygen and carbon dioxide) between the atmosphere and the plant body. Excess water also evaporates from lower epidermis. (3)...
Read more

osmoregulation in terrestrial and aquatic animals

Mechanism of osmoregulation is very important for all groups of animals whether inhibting land or water. Unlike plant cells, animal cells when placed in hypotonic solution burst due to the continuous absorption of water. On the contrary they would shrink and die if constantly placed in hypertonic solution. Normally uptake and loss of water are in balance for proper survival of cell. (1)        Osmoregulation in terrestrial animals: Terrestrial animals are more likely to loose water by evaporation through their permeable surfaces exposed to amsophere. Among various animal groups only Arthropods and vertebrates became the most successful land dwellers. They have developed number of strategies to maintain osmoregulation of their body fluid. (a) Water proof external coverings: To prevent water loss through external surfaces, vertebrates like reptiles, birds and mammals have water proof keratinized epidermis. Similarly the insects have developed...
Read more

Autobiographical elements in A Farewell to Arms

Introduction Some, literature can be satisfactorily read and discussed taking the author into account. Other literature seems inseparable from the person who created it. To an extraordinary degree Hemingway and what he has written exist in a synergetic relationship, reinforcing and fulfilling each other; he has created a personal legend which serves as an ambience in which we read him. Autobiographical Touches The novel A Farewell to Arms autobiographical elements. The love-affair between Fredric and Barkley, the hero’s injury in the battlefield, his despair and frustration, the hero’s separate peace with life are some of the characteristics of Hemingway’s life. Hemingway himself had received the injury caused by the mortar-shell at Fossalta, and he was admitted into the Milan hospital for recuperation in the late summer and autumn of 1918. He fell in love with the nurse in the Milan hospital. Carlos Baker has thrown light on this fact. In A Farewell to Arms Hemingway was d...
Read more