BIOL 2200 Exam #2 Correctly Answered Questions| UpToDate | Already Graded A+

Biodiversity : The variability among living organisms from all sources and the ecological complexes of which they are part; includes diversity within and among species and ecosystems -Prokaryotes are so important to the biosphere that if they were to disappear, the prospects of survival for many other species would be dim Why study biodiversity? : -To understand evolution of life -To appreciate nature -To assess its economic value -To see the larger impact of humans on the earth There are millions to trillions of microbial species but : Less than 1% have been described The first organisms to inhabit earth were prokaryotes : 3.5 billion years ago 2 | P a g e most prokaryotes are unicellular, have small diameters, and are 1 of 3 common shapes : o Cocci: spherical o Bacilli: rod-shaped o Spiral: spirilla, spirochetes External prokaryote structure : -cell wall -fimbraie -capsule -pili -flagella Cell wall : Maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment -bacterial cell walls contain peptidoglycan: a polymer composed of modified sugars cross-linked by short polypeptides -archaea cell walls: polysaccharides, proteins -eukaryotic cell walls: cellulose or chitin 3 | P a g e plasmolysis : In a hypertonic environment, prokaryotes lose water and shrink away from their cell wall Fimbraie : stick to substrate hair-like appendages that allow prokaryotes to stick to their substrate or to one another; usually shorter and more numerous than pili Capsule : stick to substrate -sticky layer of polysaccharide or protein that is dense and well-defined and surrounds cell wall of prokaryotes -enables prokaryotes to adhere to their substrate or to other individuals, protects against dehydration, and shields from attacks by host's immune system pili : pulls cells together for conjunction