The plateau phase of an action potential in cardiac muscle cells is due to the ________.
A. efflux of K+ through K+ channels
B. efflux of Ca2+ through fast Ca2+ channels
C. influx of Ca2+ through slow Ca2+ channels
D. influx of Na+ through fast Na+ channels
Ans: C. influx of Ca2+ through slow Ca2+ channels
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Intracellular Gram-negative diplococci found in a urethral sample from a male is indicative of
A. E. coli. B. Pseudomonas. C. Streptococcus pneumoniae. D. Neisseria gonorrhoeae.
Cork ___
A. represents the major dermal tissue in bark B. helps transport nutrients and fluid. C. serves a protective function. D. both represents the major dermal tissue in bark and helps transport nutrients and fluid. E. both represents the major dermal tissue in bark and serves a protective function.
Which of the following information led scientists to believe that archaeans belong to their own distinct
domain?
a. They have a cell wall synthesized from a unique carbohydrate. b. The genetic material of archaeans is RNA, not DNA. c. Many archaeans live in extreme environments tolerated by no other organisms. d. Archaeans do not utilize ATP to do cellular work. e. Archaeans have unique cellular structures not found in either eukaryotic or prokaryotic cells.
Adult stem cells are found only in adults. Indicate whether the statement is true or false