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12 Cards in this Set

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What hypothesis did Miller and Urey test?
The conditions on the early Earth could have permitted the sunthesis of organic molecules from inorganic ingredients.
Why was the appearance of protobionts surrounded by membranes likely a key step in evolution?
In contrast to random mingling of molecules in an open solution, segregation of molecular systems by membranes could concentrate organic molecules, and electrical charge gradients across the membrane could assist biochemical reactions
What is a ribozyme?
An RNA molecule that functions as a catalyst.
A fossilized skull has a carbon-14/carbon-12 ratio about 1/16 that of the skulls of present-day animals. What is its approximate age?
22,920 years (Four half-life reductions)
How long did prokaryotes inhabit Earth before eukaryotes evolved?
About 1.3 billion years.
What do fossilized stromatolites suggest about the evolution of prokaryotes?
Prokaryotes must have existed at least 3.5 billion years ago, when the oldest fossilized stromatolites formed.
The first appearance of free oxygen in the atmosphere must have triggered a massive wave of extinctions among the prokaryotes of the time. Why?
Free oxygen atatcks chemical bonds and can inhibit enzymes and damage cells. Some organismes were able to survive in anaerobic habitats, however.
What evidence supports the hypothesis that mitochondria preceded plastids in the evolution of eukaryotic cells.
All eukaryotes have mitochondria or genetic remnanats of these organelles, but not all eukaryotes have palstids.
How is a eukaryotic cell like a chimera?
The chimera of Greek mythology contained parts from different animals. Similarly, a eukaryotic cell contains parts from various prokaryotes: mitochondria, plastids, nuclear genome.
How does the division of function differ for a single-celled and multicellular organism?
A singe-celled organism must carry out all of the functions required to stay alive. Most multicellular organisms have many types of specialized cells, and life functions are divided among specific cell types.
Which kingdoms in Whittaker's five-kingdom system include organism now in the domain Eukarya?
Protista, Plantae, Fungi and Animalia
Explain why the kingdom Monera is no longer considered a valid taxon.
Monera included both bacteria and archaea, but archaea are more closely related to eukaryotes than to bacteria.