Compare and contrast the structure and function of the saccule and utricle with that of the semicircular
canals with regard to maintaining equilibrium. What will be an ideal response?
In mammals, the utricle, saccule, and semicircular canals function in approximately the same way in
that the deformation of hair cells in the proper direction ultimately results in an action potential being
sent to the brain. Depending on which hair cells are deformed (and in which direction), these signals
are used by the brain to determine the position of the head (utricle and saccule) and the rotation of the
head (semicircular canals). In the utricle and saccule the hair cells are covered by a gelatinous cupula
in which otoliths are embedded; gravity causes the otoliths to move within the cupula, and this
movement results in the generation of a nerve impulse. In the three semicircular canals, there are no
otoliths; instead, the canals are filled with endolymph. Rotation of the head causes movement of the
endolymph, and this movement deforms the hair cells resulting in the generation of an action potential.
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If a flower has sepals, petals, and stamens but lacks carpels, then that flower is:
a. complete and imperfect. b. complete and perfect. c. incomplete and perfect. d. incomplete and imperfect. e. almost complete and almost perfect.
Amphibians evolved directly from what ancestral organisms?
a. reptiles b. shelled invertebrates c. fishes d. soft-bodied animals e. marine invertebrates
Enumerating the viable and total cell concentration of a population of a microbial isolate can be a really laborious task for a microbiologist
Especially when a microbiologist studies the same isolate for several years, it often becomes practical to determine the relationship between optical density (OD) and cell concentration. Once this relationship (determined by a standard curve) is determined, the OD of an isolate in a broth can be routinely used to determine the population's concentration. Why must a standard curve be prepared for each isolate when using OD measurements to determine cell concentration? Also describe an experiment that would generate this type of standard curve. What will be an ideal response?
What is the function of adenylyl cyclase?
A. to form protein kinase A B. to phosphorylate protein kinase A C. to form cyclic AMP D. to phosphorylate cyclic AMP