Which of the following situations might cause normal microbiota to become opportunistic pathogens?
A. growth of microbes on the surface of intact skin
B. growth of microorganisms on the excreted cellular wastes and dead cells in the large intestine
C. treatment of a cancer patient with radiation
D. growth of Lactobacillus on the surface of teeth
E. presence of Entamoeba in the lumen of the colon
Answer: C
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An Etest ® is a clinical tool used for the determination of
A) enteric presence. B) Escherichia coli O157:H7 presence. C) the minimum inhibitory concentration (MIC) value of an antimicrobial agent. D) pathogenic enzyme activity.
Match each of the following cellular processes to the stage of meiosis in which it occurs. (Select all correct processes for each meiotic stage. Each cellular process may be used more than once.)
Stage Cellular processes prophase I a. Microtubules search for and attach to kinetochores at the centromere of each chromosome. metaphase I b. Microtubules from both sides of the spindle tether each chromosome and move them to the center of the cell. anaphase I c. Microtubules from both sides of the spindle tether each bivalent and move them to the center of the cell. telophase I d. Chromosomes condense to thickened structures that are visible under the microscope. prophase II e. The centromere divides and the sister chromatids separate. metaphase II f. The nuclear envelope reforms around the segregated chromosomes. anaphase II g. Two new chromosomes form from each original chromosome. telophase II h. The nuclear envelope disappears. i. Microtubules pull chromosomes toward opposite poles. j. The spindle assembles from tubulin dimers as the centrosomes migrate to opposite poles k. Chromosomes arrive at opposite poles of the cell. l. Chromosomes decondense. m. The spindle disappears. n. The bivalents separate and the homologous chromosomes move apart. What will be an ideal response?
The molecular fragment on an antigen molecule that a lymphocyte recognizes and responds to is called a(n) ________.
A. hapten B. epitope C. variable region D. antigen binding site
Cells of a ____ organism live together, but remain self-sufficient
a. single-cell b. multicellular c. colonial d. eukaryotic e. protist