Which component of a negative feedback mechanism is responsible for producing the result that counteracts the original environmental change away from homeostasis?
a. an integrator
b. a sensor
c. an effector
d. a stimulus
Ans: c. an effector
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DNA transfer by conjugation is more efficient in a liquid medium setting, subjected to very mild agitation (stirring), rather than on an agar plate format. Why?
A. Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the plate format than in the fluid format (especially for relatively non-motile types of bacteria). B. Direct cell-to-cell contact isn't required for this process, so the ability to secrete the DNA into the surrounding fluid medium makes the process more efficient than the dry surface of an agar plate. C. Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the fluid liquid format than on an agar plate (especially for relatively non-motile types of bacteria). D. Trick question-it can take place with the same degree of efficiency on either format. It doesn't matter!
All of the following would be appropriate for handling routine patient specimens (urines, sputums, wound swabs) for microscopy and culture EXCEPT
A. lab coat. B. gloves. C. biological safety cabinet. D. full-body positive pressure suit with air supply. E. appropriate waste decontamination.
Which of the following is NOT a true
statement about the evolution of immunity?
a. immunity evolved before there were multicelled eukaryotes b. nonself recognition evolved about 1 billion years ago c. innate immunity evolved out of adaptive immunity d. ways of indentifying “self” evolved after multicelled eukaryotes evolved e. more than one of these statements is NOT true about the evolution of immunity
For a cell to take up sugar from the bloodstream,
a. sugars must bind to receptors on cells of the pancreas. b. a person must have had a meal with sugar within the last twenty-four hours. c. homeostatic mechanisms must activate the blood-brain barrier. d. glycogen must be broken down to provide a supply of glucose. e. the pancreas must supply the appropriate enzymes to make sugar available.