How was the adaptive method for acquiring mutations disproved?
What will be an ideal response?
Luria and Delbruck argued that if mutations occurred due to exposure to a particular environment, then the number of cells that had the mutation would be similar in different identical populations. However, if the mutations occurred randomly, then the number of cells with that particular mutation would differ or fluctuate in identical populations exposed to the same environmental factor. They proved the second argument to be true by infecting identical bacterial cultures with the bacteriophage T1 and counting the number of resistant colonies. The number of resistant colonies fluctuated widely in the different cultures.
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Duplicated centrioles move to opposite poles of a(n) ____ cell during ____ of the cell cycle
a. animal; prophase b. plant; prophase c. animal; metaphase d. plant; metaphase e. both animal and plant cells; prophase
In prokaryotes, most of the control of gene
expression is at the ____ level. a. transcriptional b. transcript processing c. transport d. translational e. post-translational
Four of the five features listed below are
characteristic of cnidarians. Select the exception. a. planula larvae b. polyp form c. mesoglea d. nematocyst e. esophagus
Classify the following explanation as one of Tinbergen's four levels of explanation: "Lactose intolerance is common in hunter-gatherer societies because these human populations did not traditionally have a diet de-rived from the milk of dairy animals."
a. proximate c. evolutionary b. developmental d. phylogenetic