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.