Briefly describe the escape from adaptive conflict hypothesis for the preservation of duplicate genes
What will be an ideal response?
The ancestral gene performs two functions, but an adaptive constraint (also referred to as a conflict) is present that prevents both functions from being fully optimized at the same time: The gene cannot get better at performing function A without getting worse at performing function B. After duplication, the duplicate copies evolve to each perform one of the two ancestral functions, and because these functions are no longer performed by the same gene, the two copies are free to evolve to optimally perform a single function. (They become specialized.) The result is that both functions are performed better than by the ancestral gene.
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What can Antarctic ice core samples tell us about atmospheric CO2 levels? Select all that apply
A. Nothingâ€"ice is made of H2O and not CO2. B. CO2 ice core data confirms CO2 measurements taken directly from the atmosphere. C. Ice cores can help scientists estimate atmospheric CO2 levels from centuries ago. D. Ice cores can tell scientists exactly what plants lived on Earth centuries ago.
After which step in the Gram-stain procedure are gram-positive bacteria first distinguished from gram-negative bacteria?
a. Crystal violet b. Iodine mordant c. Gram's decolorizer d. Safranin
When reconstructing a phylogeny and creating an evolutionary tree, scientists follow which of the following guidelines?
1.The path with the greatest number of nucleotide sequence changes is selected. 2.Data from outgroups are excluded so as not to bias the tree. 3.The path with the fewest number of steps is the most likely to occur. 4.The total number of differences between the groups must always be a constant within the tree.
Nosocomial infections involve all the following except
A. are only transmitted by medical personnel. B. often involve the patient's urinary tract and surgical incisions. C. the patient's resident biota can be the infectious agent. D. Escherichia coli and staphylococci are common infectious agents. E. medical and surgical asepsis help lower their occurrence.