Algae- Introduction and types of algae -every neet- aspirants

        Introduction

 Algae are unicellular aquatic (both fresh and marine) and seedless organism. They are chlorophyll - bearing simple thalloid organism. They occur in variety of other habitats:moist stones,soils and wood. Some algae also occur in association with fungi(lichen) .
  Algae are photosynthetic organisms that mean they  use sunlight and chlorophyll for make food. More than 50% photosynthesis  only algae. Single celled algae called phytoplankton are a main source of food for fish . Certain varieties such as cyanobacteria produce toxins that can harmful for fish and other organism.






             Reproduction
1)Vegetation:
Vegetative reproduction by fragmentation. each fragment develop into a thallus.

2) asexual reproduction:
Asexual reproduction is by the production of different type of spors,The most common being the zoospores. They are flagellated motile and on germination give rise to new plant.

3) sexual reproduction
Sexual reproduction takes place through fusion of two gametes.














Three types of algae 

1) chlamydomonas: also known as green algae.they are usually grass green due to the dominance of pigment chlorophyll a and b.the chloroplast may be discoid ,reticulate, Cup -shape, ribbon shape in different species.pyrenoid is a storage body which locate in chloroplast and contain protein beside starch.
Vegetative reproduction take place by fragmentation and formation of different spores.
A sexual reproduction is by 
flagellate zoospores produced in zoosporangia.
The sexual reproduction may be isogamous(ulothrix and spirogyra) anisogamous(chlamydomonas) oogamous (chara and volvox).




2)phaeophyceae
commonly known as brown algae which primary found in Marine habitat and few in fresh habitat. They contain chlorophyll a and c carotenoid and xanthophyll.Xanthophyll pigment fucoxanthin present in them. They have two unequal later flagella . Cell wall is made of cellulose and algin. Food storage in the form of mannitol and laminaria. They found in cold region.
Isogamous- lateral flegella 
Anisogamous and oogamous both have pear shape flegella.
Eg: ectocarpus (filamentous),Dictyota, laminaria, sargassum, fucus.



3)Rhodophyceae
commonly known as red algae because of the predominance of the red pigment r-phycoeythrin and contain chlorophyll a and d.
In their body. Found in warm and mostly in Marine habitats. food storage in the form of fluoride in starch which is very similar to amylopectin and glycogen in structure.cell wall made of cellulose pectin and polysulphate ester. They have no flagella.only oogamous occur
Eg: polysiphonia,porphyra,gracilaria,gelidium.













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