Discussion on AIPMT

Cyanophyceae: Cyanophyceae comprises of prokaryotic organisms popularly known as blue-green algae. They are like gram-negative bacteria and due to the nature of the cell wall, cell structure and capacity to fix atmospheric nitrogen these are considered as bacteria and named cyanobacteria.
Euglenophyceae: The members are single cells, motile found swimming with the help of usually one prominent flagellum and in some cases with two flagella. In the anterior portion a gullet is visible and there are many chloroplasts in the autotrophic forms and the chloroplasts vary in shape.
Bacillariophyceae: The members belonging to this class are popularly known as diatoms. All are basically unicellular, in some cases become pseudofilamentous or aggregated into colonies. The cell wall of diatoms is impregnated with silica and several diatoms have been well preserved as microfossils. The diatom cell is also called as frustule and the classification of diatoms is based on the pattern of ornamentation on the wall of the frustule.
Dinophyceae: The members are unicellular motile cells with two flagella one located in the transversely aligned groove or furrow and other in a longitudinally arranged furrow. One is considered to propel the cell and the other is called the trailing flagellum. The cells while moving forward also get rotated by the flagellar action. The motile cells have a thick pellicle instead of a cell wall, which sometimes becomes very thick, and called theca.