Economical importance of bryophytes

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ECOLOGICAL IMPORTANCE OF BRYOPHYTES Mosses and Bryophytes are the first organiasms to colonise rocks. They colonise rock by acidic secretion. This acidic secretion is due to the death of mosses. When the rock is decomposed it helps in soil formation. Therefore New soils are formed. The soil act as binders.  It prevent soil erosion. The water retention capacity of the soil is high ie, water holding capacity of the soil is high.  This reduces surface water run-off which prevent soil erosion. Bryophyte helps in the recycling of nutrients. ECONOMICAL IMPORTANCE OF BRYOPHYTES. 1) SPHAGNUM Sphagnum has high absorptive power with antiseptic property. This can be used to replace cotton in bandages. 2) MERCHANTIA   Mercahntia cures pulmonary tuberculosisand affliction (pain) in liver. Antibiotic substances are also extracted from bryophytes. it also acts as antiseptic, and as preservative POLYTRICHUM Polytrichum dissolove stone in kidney and in gall bladder. 3) IN RESEARCH It is used in the fie
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Cell structure and cell wall of algae notes

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CELL STRUCTURE 
CELL WALL
FLAGELLA



CELL STRUCTURE
  On the basis of their organization algal cell maybe differentiate into prokaryotic, mesokaryotic, and Eukaryotic. Prokaryotic are primitive found in Cyanophycean algae characterised by absence of membrane bound organelles, absence of basic protein called histones in DNA. 
              A Eukaryotic cell have a well organized nucleus and membrane bound organelles. 
              Mesokaryotic cell has a nuclear membrane and chromosomes(Eukaryotic characters), basic proteins are absent and nucleus division like prokaryotic type (prokaryotic characters). Fou8 in members of Dynophyceae. 

1.CELL WALL
      Most of the non motile unicellular and multicellular algae possess a typical cellulosic cell wall of non living matter out side the cytoplasmic membrane. It composed of pure or mixed carbohydrate ( cellulose, mucilage, pectin etc.) and substances like alginic acids, fucoidin,, fucin and hemicellulose are present in brown algae, pectin in red algae, and silica in diatoms. 

      Election microscopic studies have reveled that cellulosic cell wall is composed of microfibrils which vary in thickness. They may be arranged in two layered right angle to each other, in three layered or in a random manner. The cell wall of diatoms is more complex , having pores with perforated membranes. 

    In blue green algae, the cell wall is mucopolymeric, mainly consisting of glucosamine, amino acids, muramic acids and diaminopimelic acid. 

    A true cell wall is however, absent in some algae like euglena, Gymnodium, and paramecium. They simple have a bounding membranes of cytoplasm called Pellicle. 


FLAGELLA
  Many unicellular and colonial algae, along with zoospores, possess flagella.their motility is due to presence of small Protoplasmic extension called flagella. It is found in all group of algae except Cyanophyceae and Rhodophyceae.Each flagellum is basically an extension of the cell membrane, comprising an internal axoneme of 9 doublet microtubules surrounding 2 doublets. The flagellum may be smooth or possess hairs or even scales. The different algal divisions have different flagella characteristics.
       The number of flagella varies from one to four to many. They are mainly of follow types 

1) Whiplash or acronematic-flagella have a smooth surface. 
2) 
Tinsel or pleuronematic-flagella covered with fine filamentous appendages called Mastigomes. They are further divided into three types on the basic of arrangements of Mastigomes. 
  a) Pantonematic-mastigomes are arranged in two opposite row or show radial arrangements. 
  b) pantocronematic-pantocronematic-flagella with a terminal fibril. 
  c) stichonematic- Mastigomes are develop only one side of flagellum. 

      A motile cell may have one or two types of flagella. If all the flagella are same, called isokont. and different called heterokont. 

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