ALGAE ARE SIMPLE PLANTS, AS THEY PREPARE THEIR OWN FOOD THEY ARE CALLED AUTOTROPHS. THEY LIVE IN FRESH WATER, OCEANS, MOIST SOIL, MOIST WALLS, RIVERS AND ON PLANTS LIKE GREEN GRASSES. THE ALGAE OCCUR IN GREEN, BROWN AND RED COLOURS. ALGAE ARE MICROSCOPIC, ATTAINING A SIZE OF 0.5MM IN DIAMETER BUT A FEW ALGAE WHICH GROW IN OCEAN ARE MACROSCOPIC, ATTAINING LENTH OF ABOUT 30METRES. THE BODY OF THE ALGA, KNOWN AS THALLUS, IS VERY SIMPLE IN STRUCTURE. THE BODIES OF THE ALGAE DONOT HAVE STEM, ROOTS AND LEAVES. ALGAE ARE CAPABLE OF SYNTHESIZING THEIR OWN FOOD BY PHOTOSYNTHESIS WITH THE HELP OF VARIOUS TYPESOF PHOTOSYNTHETIC PIGMENTS. BASED ON THE TYPES OF PIGMENTS PRESENT, THE ALAGE ARE CLASSIFIED AS; (1)CYANOPHYTA ( BLUE GREEN ALGAE), (2) CHLORROPHYTA ( GREEN ALGAE), (3)RHODOPHYTA ( RED ALGAE), (4)PHAEOPHYTA ( BROWN ALGAE).

THE CELLS OF BLUE- GREEN ALGAE CONTAIN GREENISH CHOROPHYLL PIGMENTS AND BUISH PHYCOCYANIN PIGMENTS. BECAUSE OF THIS THEY APPEAR BLUE - GREEN IN COLOUR. HENCE THEY ARE CALLED BLUE - GREEN ALGAE. IN ADDITION TO THESE PIGMENTS PHYCOERYTHRIN AND OTHER PIGMENTS ARE ALSO PRESENT IN THE CELLS OF BLUE -GREEN ALGAE. (E.G.) NOSTOC. NOSTOC THE MEMBERS OF THIS GROUP GROW IN WATER BODIES (PONDS,POOLS,ETC.) MOIST, SOIL AND ON THE MOIST SURFACES OF FLOWER POTS AND BARKS. THE PIGMENTS OF GREEN ALGAE ARE CHLOROPHYLL-A, CHLOROPHYLL-B, CAROTENE AND ZANTHOPHYLL. AS THE PIGMENTS CHLOROPHYLL-A AND B ARE ABUNDANTLY FOUND IN THE CELLS OF THESE ALGAE, THEY APPEAR GREEN IN COLOUR. (E.G)SPIROGYRA.

MAJORITY OF RED ALGAE ARE MARTINE FORMS. THEY GROW ON THE SURACES OF ROCKS IN THE TIDAL ZONES AND SOME OF THEM GROW IN WATER AT THE DEPTH OF ABOUT 300FT. AND MORE. ONE ARE TWO KINDS OF RED ALGAE LIVE IN FRESH WATER. THE CELLS OF RED ALGAE CONTAIN CHYOROPHYLL-A, PHYCOCYANIN, PHYCOERYTHRIN PIGMENTS ETC. THE REDDISH PHYCOERYTHRIN PIGMENTS GIVES RED COLOUR TO THESE ALGAE.(E.G) GRACILLARIA. MAJORITY OF THE ALGAE BELONGING TO PHACOPHYTA OCCUR IN MARINE WATERS. THEY GROW ATTACHED ON THE ROCKS FOUND IN THE TIDAL ZONES. SOME OF THESE ALAGE GROW ON ROCKS SUBMERGED IN SEA WATER AT DEPTH OF ABOUT 75 FT. AND MORE. EXCEPT FEW BROWN ALAGE OTHERS LIVE IN COLD SEAS. BROWN ALAGE HAVE CHLOROPHYLL-A,CAROTENE AND YELLOWISH BROWN FUCOXANTHIN PIGMENTS. AS THE FUCOXANTHIN PIGMENTS OCCUR IN LARGE AMOUT THESE ALAGE ARE BROWN IN COLOUR. PUT SMALL PIECES OF WET BREAD, COCONUT, IDLY,DHOSAI AND CITRUS FURITS INSIDE SMAL CONTINERS AND CLOSE THEM. AFTER THREE OR FOUR DAYS, THE SURFACES OF THE FOOD SUBSTANCES APPER WHITE OR BLACK. APART FROMTHIS, DURING RAINY SEASON WHITISH OR BROWNISH UMBRELLA LIKE STURCTURES ARE FOUND ON THE DECAYING WOOD, ETC.

ON THE BASIS OF THE STRUCTURE OF THE THALLUS AND REPRODUCTION, FUNGI ARE CLASSIFIED INTO FIVE MAJOR GROUPS. THEY ARE, 1.MYXOMYCETES, 2.PHYCOMYCETES, 3.ASCOMYCETES, 4.BASIDIOMYCETES, 5.DUETEROMYCETES. MYXOMYCETES HAVE PLASMODIUM TYPE OF THALLUS. IT IS AMOEBA LIKE IN STRUCTURE. THE THALLUS HAS NO CELL WALL. IN THIS RESPECT MYXOMYCETES IS NO RESEMBLE AMIMAL CELL. (E.G) PHYSARUM. IN THE OLDER CLASSIFICATION, PHYCOMYCETES IS ONE OF THE FOUR MAJOR GROUPS. AS PHYCOMYCETES HAS BEENDIVIDED INTO SIX GROUPS, NOW THE TERM PHYCOMYCETES IS INTO USED. THE FUNGI BELONGING TO THIS GROUP HAVE LONG TUBULAR HYPAE. GENERALLY THE HYPAE ARE NOT HAVING CROSS WALL(SEPTA). IN EACH HYPHA SEVERAL NUCLEI ARE PRESENT. THIS CONDITION IS KNOWN AS COENOCYTIC.

THE HYPHAE OF ASOMYCETES ARE SEPTATE. THAT IS, EACH HYPHA IS MADE UP OF SEVERAL CELLS. IN EACH CELL ONE OR TWO NUCLEI ARE PRESENT. THE SEPTEM (CROSS-WALL) HAS A SMALL PORE AT THE CENTRE(E.G) PENICILLIUM. BUT THE YEAST WHICH IS AN ASCOMYCETOUS FUNGUS IS AN UNICELLULAR ORANISM. The cross wall of basidiomycetes fungi is specialied. It is barrel-shaped and it is called dolipore septum. In each cell one or two nuclei are found. Except few basidiocarps, in which basidiospores are produced. Each basidiospore grows in to a new fungus. (e.g) agaricus The Hypae of majority of Deuteromycetes resemble the Hypae of ascomycetes. In these fungi asexual reproduction only taks place. The spores by prouduced these fungi resemble those of ascomycetes. Only those fungi in which sexual reproduction is absent are included in deuteromycetes. (e.g) colletotrichum.