Practical: Study of Nostoc

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 Practical: Study of Nostoc Nostoc is a filamentous, photosynthetic cyanobacterium. It commonly occurs in freshwater, moist soil, wet rocks and other damp habitats. Colonies are usually gelatinous because numerous filaments remain embedded in a mucilaginous matrix. Materials Required Fresh or preserved Nostoc material, clean glass slide, cover slip, dropper, dissecting needle, water, blotting paper and compound microscope. Procedure Take a small quantity of Nostoc colony with the help of a dissecting needle and place it on a clean glass slide. Add one or two drops of water and gently tease the material so that the filaments become separated. Place a cover slip carefully over the material without trapping air bubbles. Remove excess water with blotting paper. First observe the preparation under low power and then under high power of the compound microscope. Observations The plant body of Nostoc is thalloid and usually forms a soft, jelly-like colony. A colony contains numerous ...
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Oedogonium Practical

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 Sample A2

1. Supplied specimen appears as unbranched or sparingly branched filaments. The thallus is multicellular, filamentous and unbranched. Filaments are typically composed of cylindrical cells arranged end-to-end.

 

2. The filament is differentiated into three types of cells according to their position : (i) basal, (ii) intercalary and (iii) apical.

 

3. The basal cell of a filament serves as an anchor. The lowest section of the holdfast might take the form of either a disc or a finger-like structure. The upper portion is predominantly wide and curvaceous. The basal region of the cell typically lacks chlorophyll and is consequently devoid of green coloration, in contrast to the other cells within the filament.

 

4. The cell located at the apex of the filament is referred to as the apical cell. The free surface of the object is curved.

 

5. The cells located between the basal and apical cells are known as intercalary cells. These have characteristic cellular morphology. The average cell has a cylindrical shape. The cell wall is characterized by its substantial thickness and consists of three distinct layers.

 

6. A reticulate chloroplast runs parallel to the cell's long axis inside the cell wall.

 The chloroplast contains a large number of pyrenoids.

 

7. The cell contains only one nucleus. The nucleus is positioned adjacent to the cell wall and is supported by slender and fragile cytoplasmic strands.

 

8. Mature and old cells show 'cap cells' at their upper end.

……………………………..Hence The specimen is Oedogonium  sp

 

Systematic Position:

Division: Chlorophyta

          Class: Chlorophyceae

                  Order: Oedogoniales

                        Family:  Oedogoniaceae

                                    Genus:  Oedogonium





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