Transcript Slide 1

• 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 DO NOT
HAVE STEM, ROOTS AND LEAVES.
•ALGAE ARE CAPABLE OF SYNTHESIZING THEIR OWN FOOD
BY PHOTOSYNTHESIS WITH THE HELP OF VARIOUS TYPES OF
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
(4) PHAEOPHYTA
( RED ALGAE),
( BROWN ALGAE).
NOSTOC
•THE CELLS OF BLUE- GREEN
ALGAE CONTAIN GREENISH
CHOROPHYLL PIGMENTS AND
BLUISH 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.
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 OR 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 PHAEOPHYTA
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 AMOUNT, THESE ALAGE ARE BROWN IN COLOUR.
• ON THE BASIS OF THE STRUCTURE OF THE
THALLUS AND REPRODUCTION, FUNGI ARE
CLASSIFIED INTO FIVE MAJOR GROUPS. THEY ARE,
• MYXOMYCETES
• PHYCOMYCETES
• ASCOMYCETES
• BASIDIOMYCETES
• DUETEROMYCETES.
•MYXOMYCETES HAVE PLASMODIUM TYPE OF THALLUS.
IT IS LIKE AMOEBA 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 BEEN DIVIDED 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 takes place. The spores produced by
these fungi resemble those of ascomycetes. Only those
fungi in which sexual reproduction is absent are
included in deuteromycetes. (e.g) colletotrichum.