exocortis and potato spindle tuber disease in plants. Virusoids were discovered by J.W.Randles and Co-workers in .They are the small circular RNAs which are similar to viroids but they are always linked with larger molecules of the viral RNA. Prions were discovered by Stanley B. Prusiner in the year and are protein- aceous infectious particles.
They are the caus- ative agents for about a dozen fatal degenerative disorders of the central nervous system of humans and other animals. For example Creutzfeldt – Jakob Disease (CJD), Bovine Spongiform Encephalopathy (BSE) – com- monly known as mad cow disease and scrapie disease of sheep. Table . : Viral diseases Plant diseases Animal diseases Human diseases .Tobacco mosaic .
Cauliflower mosaic . Sugarcane mosaic . Potato leaf roll . Bunchy top of banana .
Leaf curl of papaya . Vein clearing of Lady’s finger . Rice Tungro disease . Cucumber mosaic .
Tomato mosaic disease . Foot and mouth disease of cattle . Rabies of dog . Encephalomyelitis of horse .
Common cold . Hepatitis B . Cancer . SARS(Severe Acute Respiratory Syndrome) .
AIDS(Acquired Immuno Deficiency Syndrome) . Rabies . Mumps . Polio .
Chikungunya . Small Pox . Chicken pox . Measles Streaks on Tulip flowers are due to Tulip Breaking Virus which belong to Potyviridae group.
Viruses of Baculoviridae group are commercially exploited as insecticides. Cytoplasmic Polyhedrosis Granulo viruses and Entomopox viruses were employed as potential insecticides. . Classification of Living World From the previous chapter we know that the planet earth is endowed with living and non -living things.
In our daily life we see several things in and around us. Imagine, you are on a trip to Hill station. You are enjoying the beauty of mountains, dazzling colour of the flowers, and melodious sound of the birds. You may be capturing most of the things you come across in the form of photography.
Now, from this experience can you mention the objects you have come across? Can you record your observations and tabulate them?. How will you organize the things? Will you