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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what is chromosome , number, shape and size, notes

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Chromosomes

     E. Strasbourger in 1875 discovered threadlike structures which appeared during cell division.these were called chromosomes ( chroma- colour) due to their affiliaty for basic dyes.in all higher organisms ( eukaryota) , the well organised nucleus contains a number of chromosomes of definite shape and size.these are invisible in the nucleus but are visible during cell division,in both mitosis and meiosis. At leptotene stage , chromosomes ( the regions of chromatin that have been compacted through localised contraction) are appeared as bead like nodules known as chronometer.size of the chromomeres and that of the interchromeric regions are not constant, so every leptotene has its own particular pattern.the DNA is believed to be present in the interchromeric regions. A diploid nucleus has two chromomeres of each type, are known as homologous chromosomes which comes in contact at zygotene and pair lengthwise throughout their length

Number
  
   Chromosome number varies from 2n -4 to 2n -  more than 1200( 1600 in some pteridophytes) . While n is the gametic or haploid chromosome number of the individual.in polyploid it become necessary to establish an ancestoral primitive number, which is represented as x and is called base number.

Shape

  It's shape is actually observed at anaphase . when the position of the primary constriction or centromere determiners it's shape.the centromere may be terminal,sub terminal,  or median in position.a terminal centromere is rod shape,a subterminal will give J shape and the median centromere will give V shaped chromomere.

Size

  A chromosome is normally measured in mitotic metaphase and may as short as 0.25 micro meter.in fungi and birds  as long as 30 micro meter ,5 micro meter In human.

All the best.....

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