Monday, January 18, 2016

Diversity in Living World



     Classification of living organisms helps us in exploring the diversity of life forms.
     The classification of life forms is related to their evolution. All organisms are classified into five major kingdoms can be done on the basis of following characteristics:
        (a)  whether they are made of prokaryotic or eukaryotic cells
        (b)  whether the cells are living singly or organised into multicellular and thus complex organisms
        (c)   whether the cells have a cell-wall and whether they prepare their own food.
     Plantae and Animalia are further divided into subdivisions on the basis of increasing complexity of body organisation.
     Living organisms can be divided into five kingdoms: Monera, Protista, Fungi, Plantae and Animalia. Woose introduced a modification in this system by dividing the Monera into Archaebacteria (or Archaea) and Eubacteria (or Bacteria) is also in use.
     Plants can be divided into five groups: Thallophytes, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms.
     Animals can be divided into ten groups: Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata, Protochordata and Vertebrata.
     The binomial nomenclature is made up of two words – a generic name and a specific name. It makes the identification of vast diversity of life around us possible.

Saturday, January 9, 2016

Changes in Our Surroundings

•    The changes take place around us can be classified into two categories:
    *    Physical changes
    *    Chemical changes
•    Some changes can be reversed and some cannot be reversed.
•    A change may occur by heating a substance or by mixing it with some other.
•    Contraction, evaporation, expansion and melting are some type of physical changes. These changes can be reversed.
•    Most of the chemical changes are generally not reversed.
•    The milk changing into curd is an irreversible change.
•    Ripening of fruits, cooking of food are also the examples irreversible change.