plants are another class of organisms. They mainly consist of bacteria, fungi, algae and flowering plants. Bacteria is unicellular (single cell) with a cell wall. DNA is present but not in distinct nucleus. Some are pathogenic--they cause disease,e.g. Mycobacterium tuberculosis causes TB. Some are non-pathogenic and useful, e.g. Bacillus thuringiensis used to destroy nosquito larvae. Other harmful bacteria include Neisseria gonorrhoen-gonorrhoea, Shigella-hacillary dysentery,bacteria-they cause diphtheria, pneumonia and tetanus, etc. For fungi, threadlike hyphae form a mycelium, They ane spread by spores. some are pathogenic, e.g. ringworm, thrush and athletes foot. Some are useful, e.g. yeast used for fermentation and fungi causes decomposition(breakdown) of waste. some fungi are used as food, e.g. mushrooms.