Symbiogenesis, or endosymbiotic theory, is an evolutionary theory that explains the origin of eukaryotic cells from prokaryotes.It states that several key organelles of eukaryotes originated as a symbiosis between separate single-celled organisms.he theory of symbiogenesis (Greek: ÏÏÎ½ syn together, Î²Î¯ÏÏÎ¹Ï biosis living, and Î³Î­Î½ÎµÏÎ¹Ï genesis origin or birth) theory were first articulated by the Russian botanist Konstantin Mereschowsky in 1910, although he described the fundamental elements of the theory were described in a paper five years earlier.
Definition of rider: Additional clause, document, or slip of paper that adds, alters, amends, or removes the provisions of an associated or attached agreement or contract (such as an insurance policy) or a negotiable ...
A green horse (or rider, for that matter) is a horse that has little or no training. Usually a horse is referred to as green after it's saddle broke, otherwise it's considered unbroke, halter broke, etc. When it comes to showing, a green horse is often a horse that has had less than 1 to 2 years of showing experience. Other times it's a horse with less than 2 years of under saddle training.