Give a brief account of range of the thallus structure in algue ?
Answers
Answer:
The range of thallus organization in algae may be classified as follows:
1. Unicellular
Motile and non-motile
2. Aggregates
Palmelloid and Dendroid
3. Colonial
(a) Colony motile
(b) Colony non-motile
4. Filamentous
(a) Un-branched
(b) Branched
5. Siphonaceous.
6. Parenchymatous
1. Unicellular Type:
The unicellular types are seen in all groups of algae with the exception of the class Phaeophyceae. The unicellular types may be amoeboid motile or non-motile, the motility being due to the movement of the flagella attached at the anterior end.
The number of flagella may be one or more, usually two or in multiples of two. The cells may have a rigid cell-wall or the outer layer of the protoplast forms do the ‘periplast‘ giving a definite shape to the cell or may allow changes in shape (rhizopodial or amoeboid type).
(a) Unicellular Amoeboid Forms or Rhizopodial Forms:
These algae lack flagella, the organs of motion, but are able to perform amoeboid movement by means of cytoplasmic growth e.g., Chrysamoeba .
Thallus Organisation: Unicellular Amoeboid Form
(b) Unicellular Motile (Flagelloid) Forms:
The unicellular motile forms are the simplest type of thallus in algae. The flagellated unicellular forms are seen in various classes of algae. The flagellated unicelled structures are distinctive of certain classes e.g., Euglenineae, Cryptophyceae, Chrysophyceae and Dinophyceae. Flagellated vegetative cells are absent in Cyanophyceae, Phaeophyceae, Rhodophyceae, Bacillariophyceae.
Nature of flagellation, type and number of flagella and the attachment of flagella, is an important character in classification. In most of the Chlorophyceae members, the flagella are usually two or in multiples of two in number, equal in size, of whiplash type and anteriorly attached.
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Answer:
ExplanatioThe range of thallus organization in algae may be classified as follows:
1. Unicellular
Motile and non-motile
2. Aggregates
Palmelloid and Dendroid
3. Colonial
(a) Colony motile
(b) Colony non-motile
4. Filamentous
(a) Un-branched
(b) Branched
5. Siphonaceous.
6. Parenchymatous