Prostaglandins are ____
a. protein molecules that act either by paracrine or autocrine mechanisms.
b. fatty acid derivatives that act either by paracrine or autocrine mechanisms.
c. neurotransmitters that act by paracrine mechanisms.
d. amine molecules that act by neuroendocrine mechanisms.
e. steroid molecules that are lipid soluble.
ANSWER: b
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A mechanism for penicillin resistance in bacteria is
A) acetylation of the antibiotic. B) phosphorylation of the antibiotic. C) confirmation change of the antibiotic. D) splitting the ?-lactam ring of the antibiotic.
The owner of a plant nursery is introducing the new night janitor to his duties. “Behind this door are the poinsettias,” she said, “Please don’t clean this room, and leave the door closed.” Why might the owner say this?
A. Poinsettias are short-day plants that require a long uninterrupted period of darkness to flower. Even a short flash of light at night could prevent flowering. B. Poinsettias are very sensitive to the chemicals used in cleaning, which can interfere with the gibberellin-dependent pathway and disrupt flowering. C. Poinsettias are tropical plants and require constant warm temperatures for flower formation. D. Poinsettias are long-day plants that require a long period of light for flower formation, and this light might disrupt the day-night cycles of other plants outside the room. Clarify Question What is the key concept addressed by the question? What type of thinking is required? Gather Content What do you already know about short-day and long-day plants? What other information is related to the question? Choose Answer Given what you now know, what information is most likely to produce the correct answer? Reflect on Process Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
A crucial step in the regulation of most bacterial genes occurs
A) at transcription initiation. B) during RNA splicing. C) during nuclear export of mRNA. D) when nonsense suppressors translate mRNAs.
The most common source of DNA mutation is
a. cigarette smoke b. UV light c. errors in DNA replication d. errors in protein synthesis e. pesticides on the food we eat