Bio Diversity


Objectives :

(i).To know the vegetative structure

            (ii). To know the reproductive structures and mode of reproduction



Apparatus : Slide, Coverslip, needle, compound microscope etc.

Material  : Spirogyra filament

Chemicals : Safranin and glycerin


Visual Observation :

            Spirogyra was a filamentous alga found in fresh water reservoirs. It was green, slippery and is also called pond scum or water silk.


Microscopic observation :

            The filament was multicellular, unbranched and made by uniseriate rows of cells. All the cells were alike. Each cell was cylindrical and consisting of peripheral cytoplasm, a centrally placed nucleus suspended by cytoplasmic threads, spiral bands of chloroplasts with pyrenoids at intervals and a large central vacuole.

            Spirogyra reproduces asexually by formation of akinete during adverse condition and aplanospores during favourable condition.

            Sexual reproduction takes place by conjugation which is of two types :- scalariform and lateral. During scalariform conjugation, two filaments come close to each other, conjugation tube is formed, each gametangium forms the gamete and fertilization takes place to form the zygospore. In lateral conjugation, two adjacent cells of filament participate and zygospore is formed.


Classification and Identification

Kingdom         :Plantae (cell wall present)

Sub Kingdom :Cryptogams (non flowering)

Division           :Thallophyta (thallus body, no tissue differentiation, no embryo formation)

Sub Division   :Algae (aquatic or semi-aquatic autotrophic thallophytes,  carbohydrate is reserve food)

Class                :Chlorophyceae(Eukaryotic algae, dominant pigment chlorophyll A and B, fresh water alga, starch food material)

Genus              :Spirogyra (Spiral chloroplast, pyrenoids present, filament unbranched and uniseriate, scalariform and lateral conjugation)

View the Figure for this Practical