Algae| plant kingdom complete notes| Types of algae|

Kingdom plantae include autotrophic eukaryotic organism. This kingdom given by Carolus. The kingdom plantae are change during every classification. In starting plant kingdom include Monera, Protista, fungi on the basis of cell wall. Kingdom plantae now include algae, bryophytes, pteridophytes, gymnosperm and angiosperm.

                                   THALLOPHYTA(Algae)

Algae are chlorophyll containing, single thalloid (Body structure), autotropic and mostly aquatic organism.

HABITAT of algae: - 

• It is found in both fresh water and marine water.
• Some algae are also found in moist terrestrial habitat like wall, soil, wood etc.
• Some algae are also found in symbiotic association like fungi (lichens).
• few are as Parasites.

Thallus (Body) organization of algae: -

• The plant body does not show differentiation. 
• The basic form and size are highly variable.
• They are unicellular form to colonial (group form).
• Filament present. 
• Filaments algae is attached to substratum.

Structure of algae: -

• If has eukaryotic plant cell structure.
• The cytoplasm contains membranous bound cell organelles like Golgi bodies, mitochondria etc.
• Cell wall contains cellulose. 
• The nucleus contains nuclear membrane.

Food material of algae: -

• Algae have main food reserve as starch.

Reproduction of algae: - 

• Algae reproduce both types sexually and asexually.
• Asexual reproduction by spore formation. e.g., Chlamydomonas algae (zoospores form)

• Asexual reproduction by vegetative parts (roots, stem, leaf) is called vegetative propagation occur by fragmentation. e.g., Ulothrix.
• Sexual reproduction occurs by fusion of two gametes.
• On the bases of morphology of reproductive cell sexual reproduction in algae are three types:
• (i) Isogamous 
• (ii) Anisogamous
• (iii) Oogamous 

(i) Isogamous: -When both the gametes are morphologically similar, and function is Unknown.

(ii)Anisogamous: -In these gametes are morphologically dissimilar but structurally similar.

(iii)Oogamous: -Male gametes smaller in size but motile and Female gametes are large but non -motile.

Economic importance of algae: - 

• Algae is responsible for carrying out half of total carbon dioxide fixation on earth during photosynthesis.
• Some form of marine brown and red algae produce large amount of hydrocolloid.
• Some protein rich algae like chlorella and spirulina are used as food supplement.
• Algae gelidium and gracilaria are used to produce agar used in Ice cream and jellies.
• About 70 species of marine are used as food. 

Classification of algae: -

On the basis of pigmentation, it is divided into three main class: -

(i) Chlorophyceae (green algae) 

(ii)Phaeophycean (brown algae)

(iii)Rhodophyceae (Red algae)

(i) Chlorophyceae (green algae): -

• The member of Chlorophyceae is commonly known as green algae.
• These are about 7000 species.
• Habitat =They are mostly marine, and few are fresh water.
• Cell organization: -They are unicellular Eukaryotic organism it is also found in multicellular form. Cell walls contain cellulose. It has chloroplast. Chloroplasts contain photosynthetic green pigment called chlorophyll. Pyrenoids located in the chloroplast. It is the storage parts of the plant bodies it is one or more than one in plant. Pyrenoids contain protein body and starch. Some algae store the food as oil drops. 
• Thallus organization: - The body may be flagellated and non-flagellated. e.g., Chlamydomonas (Flagellated) and chlorella (non flagellated). It is found in about 10cm, nucleus contain rhizoids.

• Reproduction: - It show various type of reproduction.
• (i) Vegetative reproduction: - cell division (unicellular organism) Fragmentation, stolens.
• (ii)Asexual reproduction by zoospores (movable spore)
• (iii)Sexual reproduction by isogamy anisogamy and oogamy.
  
  

Phaeophycean: - (brown algae)  

• It is commonly known as brown algae.
• The members of this group contain fucoxanthin pigment.
• This pigment includes phycocolloids rich multicellular eukaryotic algae. It includes 2000 species.
  
  

                                                             
• Habitat: - It is mostly marine, found in cold seas and during cold season.

Size: -These are larger algae found in 100m in length. e.g., Microcysts (40-100m), Neurocytes (20-30m). They are simple and branched.

Cell organization: - All membrane of these groups is multicellular. Cell wall present, cell wall contains cellulose. The cellulose wall of vegetative cell internal covered by gelatinous called Algin.

• Thallus: -The plant body consists of following parts.
• (i)Holdfast
• (ii)Stipe
• (iii)Frond 
• (iv)Air bladder

Rhodophyceae (red algae): -

It is commonly known as red algae. e.g.: - Porphyra, Polysiphonia.

Habitat: -It is mostly marine found in warm sea where sunlight effect its high. 

Thallus: -They are mostly multicellular body organization is complex cell wall. Cell walls contain cellulose and peptic compound.

Reproduction: -

• Vegetative reproduction by fragmentation 
• Asexual reproduction by non -motile spore (conidial spore)
• Sexual reproduction by non-motile gametes i.e., Oogamous type.