Remember that prokaryotic cells are simple and do not contain membrane-bound organelles and that eukaryotic cells are more complex and do contain membrane-bound organelles, as well as a nucleus. The endosymbiosis theory explains how eukaryotic cells may have evolved from prokaryotic cells. Symbiosis is a close relationship between two different organisms. We saw that, over time, one ancient cell became the host for other ancient cells that were capable of specific activities.
aviary, An aviary is a large enclosure for confining birds. Unlike cages, aviaries allow birds a larger living space where they can fly; hence, aviaries are also sometimes known as flight cages. Aviaries often contain plants and shrubbery to simulate a natural environment.
Full Definition of AESTHETIC. 1. 2. : appreciative of, responsive to, or zealous about the beautiful; also: responsive to or appreciative of what is pleasurable to the senses. There are practical as well as aesthetic reasons for planting trees. 2  making aesthetic improvements to the building. 3  My generation has an annoying penchant for treating luxuries as necessities and turning guilty pleasures into aesthetic and even moral touchstones.