The 1st level at which energy will enter an ecosystem is via the:
a. primary consumers
b. secondary consumers.
c. tertiary consumers.
d. secondary producers.
e. primary producers.
e
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Is it as effective to take two antibiotics sequentially for an infection as it is to take them simultaneously, so long as the total length of time of the treatment is the same?
A. No. There's always one specific antibiotic that will be the most effective, and that is the only antibiotic that should be used to treat a particular infection. B. Yes. So long as the length of time is the same, the two treatments should be essentially the same in terms of effectively eliminating the infection. C. No. Taken sequentially, the first antibiotic will select for the small portion of the population that will spontaneously mutate towards resistance. Then, the second antibiotic will do the exact same thing-selecting for resistance to the second drug from the few bacterial cells that remained from the first drug treatment. D. It depends. Provided that the majority of the infectious agent is killed off by the first drug, the likelihood that the few that are left would not also be killed by the second drug is low. However, simultaneous treatment should be more effective at eliminating all the microbes in the shortest time possible, and with the least probability of selection for multiple drug resistance mutations.
When the immune system is activated by a normally harmless antigen, this is called
a. an allergy. b. an innate response. c. a complement response. d. cytotoxic cell response.
Formation of a tetraploid plant from two different diploid parental species of plants is an example of speciation.
A. parapatric B. prezygotic C. allopatric D. postzygotic E. sympatric
Courtship for Anolis lizards involves the male displaying a dewlap (skin under the throat area) that varies in appearance based upon the species. Lizards that are found in darker, more shaded environments will have dewlaps that are lighter in color because they are more noticeable by potential mates. Which of the following mechanisms best explains how speciation is at work in this example?
A. Genetic drift B. Postzygotic isolation C. Natural selection D. Reinforcement