Test Preparation on Biology-Biological Classification

Members of Phycomycetes are found in aquatic habitats and on decaying wood in moist and damp places or as obligate parasites on plants. The mycelium is aseptate and coenocytic.

They have a ribbon-like transverse flagellum with multiple waves that beats to the cell's left, and a more conventional one, the longitudinal flagellum, that beats posteriorly. The transverse flagellum is a wavy ribbon in which only the outer edge undulates from base to tip, due to the action of the axoneme which runs along with it. The longitudinal flagellum is relatively conventional in appearance, with few or no hairs. It beats with only one or two periods to its wave.

: Since viruses are obligate intracellular parasites, the term conveys the idea that viruses must carry out their reproduction by parasitizing a host cell. They cannot multiply outside a living cell, they can only replicate inside of a specific host. The viruses are smaller than bacteria so they can easily pass through bacterial filters. Virus is made up of genetic material and a protein coat

1. Cell walls: virtually all bacteria contain peptidoglycan in their cell walls; however, archaea and eukaryotes lack peptidoglycan. 2. Fatty acids: bacteria and eukaryotes produce membrane lipids consisting of fatty acids linked by ester bonds to a molecule of glycerol. In contrast, the archaea have ether bonds connecting fatty acids to molecules of glycerol. 3. Complexity of RNA polymerase: transcription within all types of organisms is performed by an enzyme called RNA polymerase, which copies a DNA template into an RNA product.