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 ...
When someone says that the horse is green, it means that the horse is not trained. If they describe a rider as green, it means that they don't know how to ride a horse.Together, a green horse and a green rider is a VERY bad combination.Source(s): Tons of horse experience.hen someone says that the horse is green, it means that the horse is not trained. If they describe a rider as green, it means that they don't know how to ride a horse.