Algae and Heterotrophic Protist - Botany - Lecture Slides, Slides for Botany and Agronomy. Central University of Haryana
prakash9 January 2013

Algae and Heterotrophic Protist - Botany - Lecture Slides, Slides for Botany and Agronomy. Central University of Haryana

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These are the important key points of lecture slides of Botany are:Algae and Heterotrophic Protist, Protista, Group of Organisms, Photosynthetic Organisms, Complex Multicellular Forms, Simple Plants, Eukaryota and Bacter...
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Slide 1

Protista: Algae and Heterotrophic



• diverse group of organisms, comprising those eukaryotes that are not animals, fungi, or plants. They are usually treated as the kingdom Protista


• photosynthetic organisms that occur in most habitats.

• vary from small, single-celled forms to complex multicellular forms- giant kelp 65 meters in length.


• regarded as simple plants, they actually span more than one domain, including both Eukaryota and Bacteria (see Blue- green algae), as well as more than one kingdom, including plants and protists, the latter being traditionally considered more animal-like (see Protozoa).

• All lack leaves, roots, flowers, seeds and other organ structures that characterize higher plants (vascular plants).


• All algae have photosynthetic machinery ultimately derived from the cyanobacteria, and so produce oxygen as a byproduct of photosynthesis

• algae produce about 73 to 87 percent of the net global production of oxygen

• far more common in moist, tropical regions than dry ones, because algae lack vascular tissues and other adaptations to live on land.

• Algae can endure dryness and other conditions in symbiosis with a fungus as lichen.

Role in Aquatic Ecology

• Microscopic forms that live suspended in the water column — called phytoplankton — provide the food base for most marine food chains.

Ecology of algae • Play a role comparable to the role played by plants in the far young

terrestrial world. • Dominant in freshwater habitats • Ponds • Streams • Lakes

Rocky shores

• Seaweeds • Members of red, brown and

green algae

• At low tides can see distinct layers that can withstand large fluctuations of humidity, temperature, salinity and light


• Beyond the zone of waves massive brown kelps form forest

• Provide shelter for diverse fish and invertebrate animals


• Plankton- minute photosynthetic cells along with tiny animals

• Phytoplankton- photosynthetic algae and cyanobacteria

• Phytoplankton is the beginning of the food chain for heterotrophic organisms that live in oceans of bodies of freshwater

Protista: Algae and Heterotrophic Protists

• Dinoflagellates : Phylum Dinophyta • Euglenoids: Phylum Euglenophyta • Cryptomonads: Phylum Cryptophyta • Haptophytes: Phylum Haptophyta • The Heterokonts- oomycetes, diatoms, pyhaeophyta • Red Algae: Phylum Rhodophyta • Green Algae: Phylum Chlorophyta • The Slime Molds

Marine Phytoplankton • Dinoflagellates- Phylum

Dinophyta • Euglenoids: phylum • Haptophytes: phylum • Heterokonts- Oomycetes,

Diatoms, Phaeophyta

Most important eukaryotic members of the marine phytoplanton and therefore essential to the support of marine animal life

Algae and “The Carbon Cycle” • Algae are able to transform carbon dioxide into carbohydrates or into

calcium carbonate • Today phytoplankton absorb about One-half of all the Carbon dioxide that

results from human activities • White cliffs of Dover- calcium carbon deposits “CO2 drawdown” effect

Dinoflagellates: Phylum Dinophyta

• Molecular systematic data- Related to ciliated protozoa such as Paramecium and Vorticella

• Unicellular biflagellates • Marine and freshwater • Some dinoflagellates are nonmotile • Reproduction- longitudinal cell division


• About half lack a photosynthetic mechanism

• Ingest solid food particles (tubular process peduncle suction organic material)

• Or absorb dissolved organic compounds • Many photosynthetic dinoflagellates can

feed in these ways- • Mixotrophy- the ability to utilize both

organic and inorganic carbon sources.

Symbiotic forms

• Zooxanthellae- responsible for the photosynthetic productivity that makes possible the growth of coral reefs in tropical waters

Dinoflagellates produce toxic or bioluminescent compounds

• Toxic glycoside released by activated dinoflagellate cysts

• Paralyze the respiratory tract, dinoflagellates feed on fish then return to cyst stage

Euglenoids: Phylum Euglenophyta

• Earliest euglenoids were phagocytes • Mostly Freshwater • Contain chloroplast • Studies suggest that euglenoids were

derived from endosymbiotic green algae • 2/3 are colorless heterotrophs that rely

upon particle feeding or absorption • Euglena

Euglena • Unicellular • Lacks cell wall or

rigid structure covering plasma membrane

• Beneath plasma membrane pellicle

• Swimming Euglena have a single long external flagellum



Crytomonads; Phylum Crytophyta

Haptophytes : Phylum Haptophyta

• Mostly Marine phytoplankton • Few freshwater and terrestrial forms are

known • Unicellular flagellates, colonial flagellates,

colonial flagellates and non-motile single cells and colonies

• Haptonema- threadlike structure that extends from the cell and can help catch prey, and sensory

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