Permeability of which ion is affected by a positive feedback mechanism once threshold is reached?
a. sodium.
b. potassium.
c. calcium.
d. chloride.
e. protein.
A
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Connie recently celebrated her 45th birthday. She feels okay most of the day, but in the morning, for about a half hour after she gets out of bed, all of her joints feel stiff. This is due to
A. sprains. B. torn ligaments. C. nerve damage. D. changes in collagen structure.
The ossicular system transmits the vibrations of the tympanic membrane to the oval window, movement of which first sets up pressure waves in the endolymph
Indicate whether the statement is true or false
A reduction in the secretion of ____ may serve as the trigger for the onset of puberty
a. inhibin b. melatonin c. adrenal androgens d. gonadotropin-releasing hormone e. pituitary gonadotropic hormones
Which of the following statements is not a tenet of modern cell theory?
A) All organisms are composed of cells and cell products. B) An organism's structure and all of its functions are ultimately due to the activities of its cells. C) All cells occupy space. D) The cell is the basic structural and functional unit of life. E) All cells come only from preexisting cells.