E. coli is a species of bacteria that causes many different infections in humans. Certain E. coli strains have developed resistance to antibiotics, making Infections with these strains difficult to treat. How do bacteria such as E. coli, which reproduce asexually gain new traits such as
antibiotic resistance?
OA by undergoing spontaneous mutations when they replicate, which increases genetic variation in a population
OB. by adapting to changes in environmental conditions without undergoing changes in their DNA
O c. by producing offspring with new gene assortments from genetic recombination, which increases diversity in a population
OD. by mutating their DNA in response to environmental conditions to gain beneficial traits
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INTL

Choose the incorrect statement (a) the motor end plate membrane is only capable of generating graded potentials, but it is contiguous with the skeletal muscle sarcolemma, which can generate action potentials. (b) propagation of an action potential through the t-tubules into the sarcoplasmic reticulum triggers the release of ca++ into the cytoplasm of a skeletal muscle fiber. (c) the generation of suprathreshold endplate potentials in multiple muscle fibers could be due to the increased frequency of action potential generation at the axon hillock of a single motor neuron. (d) a greater amount of ach would be found in the presynaptic vesicles of a motor unit that fired several action potentials after exposure to botulinum toxin, than in a motor unit that fired several action potentials after exposure to the venom of the krait snake (which contains α-bungarotoxin).