Virus

Viruses are not actually cells. They do not need food as a source of energy. The only living process occurs in virus is reproduction; but they can not reproduce independently.

                                          Virus have a coat of protein enclosing a strand of nucleic acid. Only one nucleic acid is found in a virus. That can be either DNA or RAN. DNA is Deoxyribo Nucleic Acid. And RNA is Ribo nucleic Acid. Viruses infect and take over the biological machinery of cells to reproduce new viruses. Viruses are totally parasitic. Chicken pox, measles, aids, common cold, influenza are some diseases caused by viruses.                                                  

Protozoa

Amoeba

Protozoa are unicellular organisms. Protozoa can be subdivided in to Rhizopods, Ciliates, flagellates and sporozoans.

                  Rhizopods can move by means of pseudopodia. They also catch their prey by means of these catch their prey by means of these pseudopodia.

  

eg. Amoeba.

 

Microscopic hairs called cilia are present around the cell in ciliates. They use these cilia for feeding and movement. Paramecium is an example for ciliates.

FUNGI

Most fungi are multi cellular. Yeast is an exception and it is a unicellular fungus. Multi cellular fungi are made up of hyphae. Hyphae are fine thread like structures.

                          No chlorophyll is present in fungi. Fungi are saprophytic, parasitic or symbiotic. Saprophytic means living on dead organic matter.                                 

                     Parasitic means grows feeds and shattered on or in a different organism while contributing nothing, to the survival of its host. Symbiotic means helping each other for nutrition.(mutually advantageous) eg. Lichens are a symbiotic partnership between algae and fungi.

                                     Yeast feed by changing sugars into alcohol, a process known as fermentation. 

     

ALGAE

Some algae are unicellular i.e. their bodies are composed of only one cell. They can only be seen under a microscope.

                  The largest algae are giant seaweeds some of which grow to over 50 meters long. They contain the green pigment chlorophyll and can produce, food by photosynthesis.

                              Green algae are formed in the sea, in fresh water, and in damp places on land. They occur as single cells, hollow bellow of cells, and fine threads.

Green Alga

                                              

Algae are of four types.

 

Rad Alga

01.   Green algae

02.   Brown algae 

03.   Red algae

04.   Diatoms

 

Diatoms are microscopic, single celled algae whose cell walls are made of silica.

 Some examples for green algae are,

 

                    01. Chlamydomonas  
                02. Ulva    
                03. Spirogyra

Ulva