In autocrine signaling, _________.
a) the messenger molecules reach their target cells via passage through bloodstream
b) the messenger molecules travel only short distances through the extracellular space to cells that are in close proximity to the cell that is generating the message
c) the messenger molecules are usually limited in their ability to travel around the body because they are inherently unstable or they are degraded by enzymes or they bind to extracellular matrix
d) the cell producing the messenger expresses receptors on its surface that can respond to that messenger
Ans: d) the cell producing the messenger expresses receptors on its surface that can respond to that messenger
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The reduction of atmospheric nitrogen to ammonia is called ________.
A. nitrification B. denitrification C. nitrogen fixation D. ammonification
Transcription begins near a site in the DNA called the ________, while the terminator specifies the end of transcription.
A. promoter B. enhancer C. response element D. transcription unit E. regulatory sequence
Which of the following statements is not true of the TCA cycle?
A) Oxidation occurs at three steps in the TCA cycle. B) Decarboxylation occurs at two steps in the TCA cycle. C) ATP/GTP is generated at one point by substrate-level phosphorylation. D) Acetate enters the TCA cycle and joins a four-carbon acceptor molecule to form citrate. E) FAD is an electron acceptor in the cycle.
Discarded or lost drift nets will have a large impact on:
a. schooling fishes. b. marine mammals. c. benthic invertebrates. d. zooplankton. e. both a and b