The word Protozoa is derived from two Greek words: protos means first; zoon means animal. They are the first animals with a protoplasmic grade of body organization. They are simple, unicellular microscopic organisms which may be solitary or colonial. All the vital activities are performed by a single cell so no physiological divison of labour … Read more
Organisms obtain their food materials in different ways which are of two types generally. They are: A) Autotrophic nutrition B) Heterotrophic nutrition. A) Autotrophic nutrition Gr.autos=self, trophein=to nourish. Also known as holophytic. In this type, organisms synthesize their own nutrients from inorganic constituents of the environment. Typically found in all … Read more
multicellular with tissue grade of body organization. aquatic, mostly marine, few are found in fresh water. sedentary or free swimming. mostly radially symmetrical whereas few are asymmetrical. diploblastic i.e. outer layer is called ectoderm and inner layer is called endoderm. There is a jelly like layer present in between these 2 layers called mesogloea. … Read more
The five kingdom system of classification was proposed by R.H Whittaker in 1969. This classification is based on following criteria: Complexity of cell structure- prokaryote and eukaryote. Complexity of organism’s body- unicellular and multicellular. Mode of obtaining nutrition– autotrophs and heterotrophs. Life style i.e. producers, consumers and decomposers. Phylogenetic relationship. The five kingdoms are Monera, … Read more