Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol nonfermenter and a nonhalophilic mannitol nonfermenter. Here the medium acts as a ________ medium.
A. enrichment
B. selective and differential
C. selective
D. differential
Answer: C
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Now extinct, tooth parts of ____ are abundant as fossils dating from the early Paleozoic to the early
Mesozoic era. These jawless fishes are considered to be the earliest vertebrates with bonelike structures.
a. acanthodians b. conodonts c. osteolepiforms d. placoderms e. ostracoderms
The feeding habits of lampreys are best described as ____
a. suspension feeding b. predatory c. parasitic d. scavenging e. filter feeding
In bacterial cells, the tryptophan operon encodes the genes needed to synthesize tryptophan. What happens when the concentration of tryptophan inside a cell is high?
a. It activates the tryptophan repressor, allowing transcription of the tryptophan operon. b. It inactivates the tryptophan repressor, allowing transcription of the tryptophan operon. c. It activates the tryptophan repressor, which shuts down expression of the tryptophan operon. d. It inactivates the tryptophan repressor, which shuts down the tryptophan operon. e. It activates the tryptophan repressor, which breaks down excess tryptophan.
Which of the two systems listed work together to bring oxygen into your body and deliver it to your cells?
A) respiratory and digestive B) urinary and cardiovascular C) respiratory and cardiovascular D) lymphatic and endocrine