Unicellular green algae like Chlamydomonas reproduce through binary fission and flagellated zoospores. Algae are classified based on their photosynthetic pigments. Green algae contain chlorophyll a, chlorophyll b, and carotenoids. Spirogyra is a filamentous green alga with cylindrical cells arranged in helical filaments. It reproduces asexually through fragmentation and sexually through scalariform and lateral conjugation. Volvox is a colonial green alga. Red algae exhibit varied multicellular forms and contain the red pigment phycoerythrin.

1. •Algae

2. Unicellular Green Algae - Chlamydomonas
• Chlamydomonas reproduces by binary fission and produces
flagellated zoospores for sexual reproduction
• Organisms such as Chlamydomonas are believed to be
evolutionary ancestors of other species

3. Kingdom Protista
The most ancient eukaryotic kingdom
Protists include a variety of eukaryotic forms;
they are mostly solitary, some colonial or
multicellular, autotrophic, or heterotrophic and
mostly aerobic
Perhaps they are best defined as eukaryotes
that are NOT fungi, animals, or plants

4. Classification of algae based on the types of pigments
Taxonomic Group Photosynthetic Pigments
chlorophyll a, chlorophyll
Cyanobacteria
c, phycocyanin, phycoerythrin
Chloroxybacteria chlorophyll a, chlorophyll b
Green Algae
chlorophyll a, chlorophyll b, carotenoids
(Chlorophyta)
Red Algae chlorophyll a, phycocyanin, phycoerythrin,
(Rhodophyta) phycobilins
chlorophyll a, chloorphyll c, fucoxanthin and
Brown Algae (Phaeophyta)
other carotenoids
Golden-brown Algae chlorophyll a, chlorophyll c, fucoxanthin and
(Chrysophyta) other carotenoids
chlorophyll a, chlorophyll c, peridinin and
Dinoflagellates (Pyrrhophyta)
other carotenoids
Vascular Plants chlorophyll a, chlorophyll b, carotenoids

5. Chlorophyta Green Algae – Forms and examples
A diverse group of fresh water algae but a few are marine forms
The body may be unicellular and motile as in Chlamydomonas or
colonial as in Volvox or filamentous as in Ulothrix and Spirogyra and
may be plant like marine forms as in Fristschiella and Ulva
The cells possess one to many chloroplasts in characteristic shapes in
different examples. Photosynthetic pigments are chlorophyll a,
chlorophyll b, carotenes and xanthophylls

6. Green Algae - Reproduction
Vegetative reproduction occurs by cell division, fragmentation
and stolon formation
Asexual reproduction occurs by the formation of akinites ,
zoospores or aplanospores
Sexual reproduction involves isogamy or anisogamy or oogamy.
Zygote is the only diploid structure in the life cycle. There is a
regular alternation of haploid gametophytic and diploid
sporophytic generations in the life cycle.
• Zoospores: flagellates with eye-spot and contractile vacuole
• Aplanospores: non-flagellated cells with contractile vacuole
• Autospores: non-flagellated cells lacking contractile vacuole
• Terrestrial species predominantly form autospores

7. Filamentous Green Algae - Spirogyra
• Spirogyras are multi-cellular and all the cells of these organisms are haploid and
cylindrical in shape
• Spirogyra cell wall is surrounded by mucilage
• The chloroplast in Spirogyra is wound spirally just inside the cell wall, central
region of the cell is filled with vacuole, and the nucleus
•is suspended by threads of cytoplasm in the cell vacuole

8. Reproduction in Spirogyra
Asexual reproduction in Spirogyra happens via the
fragmentation of cells (below left)
Sexual reproduction in Spirogyra is of two types, scalariform
conjugation and lateral conjugation (below right)

9. Colonial Green Algae - Volvox

11. Rhodophyta ( Red Algae) forms
• Red algae are multi-cellular aquatic algae which exhibit a
highly varied organization of the plant body
• Are commonly called 'red algae' due to the presence of a
characteristic red pigment called phycoerythrin (red),
which masks the color of other pigments like
phycocyanin (blue) and chlorophyll (green)
• They are generally found attached to rocky stones. Some
occur as total or semi parasites on the other algal plants