Your textbook presented the experiments of Richard Lenski and his colleagues who set up long-range experi-ments on E. coli
The experimental set up is illustrated in the figure above. In these experiments, 12 parallel experimental line-ages were created, cells from each line were periodically frozen, and the team followed the lineages for more than 50,000 generations. Why are these experiments groundbreaking? How have these experiments revolu-tionized the sorts of questions evolutionary biologists can ask?
What will be an ideal response?
ANS:
Will vary, but could include: the ability to observe and manipulate more than one evolutionary pathway; the ability to store, archive, experiment, and compare living ancestors with current lineages; the open-endedness that allows for a large number of potential experiments. Also, the high reproductive rate and short generation time of microbes allows for the accumulation of tens of thousands of generations within a reasonable time frame.
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48. If, according to one hypothesis, Najash evolved from terrestrial, burrowing snakes, which of the following best reflects the adaptive or selective benefit for other snakes to have lost their pelvis and hindlimbs?
A. In situations of flooded burrows and land surface, the snakes could swim better without hindlimbs and pelvis. B. Grasping prey would have been easier and more efficient without the hindlimbs and pelvis. C. Chasing prey through tunnels and burrows could be easier without the function and obstruction of hindlimbs and pelvis. D. Chasing prey would have been easier, because the snakes would be much faster without hindlimbs and pelvis. E. Burrowing snakes would be better able to dig their burrows without the hindlimbs and pelvis.
The incorporation of a single strand of donor DNA into a recipient DNA duplex so that the donor strand replaces one of the strands or the recipient duplex generates ________ DNA.
A. unstable B. heterogeneous C. heteroduplex D. aberrant
A new arrow labeled "lengthens" could be added between __________.
a. "target DNA" ? "DNA strands" b. "primers" ? "DNA strands" c. "Taq polymerase" ? "primers" d. "target DNA" ? "primers"
Which is false about insomnia?
-it is the complain or poor sleep quality with daytime functional impairment or distress for at least 1 month -to meet criteria for sleep onset insomnia a patient must have a sleep latency of greater than 30 minutes -Patients with sleep maintenance insomnia have difficulty staying asleep -Patients with sleep maintenance insomnia have difficulty staying asleep with frequent and extended awakenings totaling 15 minutes in time