Which of the following is not part of the respiratory system?
A. bronchus
B. trachea
C. esophagus
D. pharynx
E. nasal cavity
Answer: C
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Cylindrical layers of meristem that run lengthwise through shoots and roots, and allow for thickening, are called ____
a. lateral meristems b. apical meristems c. ground meristem d. Procambium e. Protoderm
What is the light used for in Chlamydomonas?
a. as a source of information about the external environment b. as a source of information about the internal environment c. as a source of energy and as a source of information about the external environment d. as a source of energy
Cultures of a bacterial species were incubated on the shelf of a refrigerator, out on a lab bench top, on the shelf of a 37°C incubator and on the shelf of a 50°C incubator. After incubation, there was no growth at 37°C and 50°C, slight growth out on the bench top and abundant growth at refrigeration. What term could be used for this species?
A. Psychrophile B. Mesophile C. Halophile D. Capnophile E. Anaerobe
Why might a large number of competing microorganisms in a food sample result in lack of sensitivity of culture methods for detecting pathogens?
A. Many microbes secrete compounds that can be toxic for their competitors. If you need a pathogenic microbe to grow in a culture in order to detect it, these toxic compounds might inhibit the growth of the pathogen and impede the test. B. You can't obtain a pure culture from a food sample that has a large number of microbes present. It would be impossible to detect only one from within the sample. C. Culture methods often rely on biochemical changes taking place in medium for identification. With multiple microbes present, you may not be sure that the biochemical change observed is from the presence of a pathogen or from some other non-dangerous bacterium that also induces the biochemical change. D. The sheer number of microbes present might shut down the growth/replication of a pathogenic microbe in a food sample due to a 'starving out' effect. If it can't grow/replicate, it won't be detectable by a culturing method test. E. Many microbes secrete compounds that can be toxic for their competitors. If you need a pathogenic microbe to grow in a culture in order to detect it, these toxic compounds might inhibit the growth of the pathogen and impede the test AND culture methods often rely on biochemical changes taking place in medium for identification. With multiple microbes present, you may not be sure that the biochemical change observed is from the presence of a pathogen or from some other non-dangerous bacterium that also induces the biochemical change.