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Description: A few representatives of life’s diversity. Bacteria are the most numerous organisms on Earth. Clockwise from upper left, a bacterium with a row of iron crystals that acts like a tiny compass; a common resident of cat and dog stomachs; spiral cyanobacteria; types found in dental plaque. Living things differ in their observable characteristics Biodiversity Scope of variation among living organisms Various classification schemes help organize the variation One broad classification is based on whether organism has a nucleus Nucleus: sac with two membranes that encloses and protects DNA Bacteria and archaea Organism types with DNA not contained within a nucleus Single-celled Prokaryotes Older designation for organisms without a nucleus Eukaryotes DNA contained within a nucleus Picture Stats: Views: 235 Filesize: 964.02kB Height: 536 Width: 714 Source: https://biology-forums.com/index.php?action=gallery;sa=view;id=42014 |