BIOL 2200 Exam #2 Questions And Answers Graded A+

Biodiversity - Answer-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? - Answer--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 - Answer-Less than 1% have been described The first organisms to inhabit earth were prokaryotes - Answer-3.5 billion years ago most prokaryotes are unicellular, have small diameters, and are 1 of 3 common shapes - Answer-o Cocci: spherical o Bacilli: rod-shaped o Spiral: spirilla, spirochetes External prokaryote structure - Answer--cell wall -fimbraie -capsule -pili -flagella Cell wall - Answer-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 plasmolysis - Answer-In a hypertonic environment, prokaryotes lose water and shrink away from their cell wall Fimbraie - Answer-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 - Answer-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 - Answer-pulls cells together for conjunction appendages that pull two cells together prior to DNA transfer from one cell to the other -Pili aren't always there, they are formed during conjugation and they facilitate the movement of DNA flagella - Answer-mobility-may be scattered over entire surface or concentrated at ends -composed of different proteins 3 main parts of bacterial flagella - Answer-motor, hook, and filament The flagella of prokaryotes and eukaryotes have similar functions, but different origins, this trait is therefore - Answer-a homoplasy and due to convergent evolution -analogous structures Taxis - Answer-a directed movement toward or away from a stimulus -Positive chemotaxis: move toward nutrients/oxygen -Negative chemotaxis: move away from a toxic substance exaptation - Answer-process in which structures originally adapted for one function take on new functions through descent with modification Internal prokaryote structure - Answer--aerobic -photosynthetic -chromosomes -plasmids aerobic prokaryotes - Answer-respiratory membrane (like mitochondria) -NEED oxygen -help with the production of energy photosynthetic prokaryotes - Answer-thylakoid membrane (like chloroplasts) -cyanobacteriachromosomes - Answer-prokaryotes have circular chromosomes, contain less DNA than eukaryotes plasmids - Answer-small rings of DNA that replicate independently from chromosomal DNA