Cells may need to respond to changes that occur rapidly in their environment. Which of the following is the most rapid response that cells can use to change the activities of gene products?
A. covalent modification of proteins
B. alter the transcription levels of genes
C. change the rate of protein transport
D. modify the chromatin structure around genes
A
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Insects such as mosquitoes and beetles can beat their wings at tremendous speeds. This can be accomplished because
A. their wing muscle contractions causes another set of muscles to stretch which in turn produces another contraction without waiting for the arrival of a nerve impulse. B. their wing muscle contractions cause another set of muscles to relax which in turn produces another wing movement. C. their wing muscle contractions are stimulated by the continuous nerve signal impulses which produce a continuous contraction of their wing muscles. D. their wing muscle contractions are capable of producing more ATP which allows these insects to have much faster and sustained wing movements. E. their wing muscle contractions produce nerve impulses which lead to more contraction of the wing muscles which in turn permits faster motion of the wings.
Studying the Sepia apama cuttlefish, Hanlon, Naud, and their colleagues observed that most success in producing fertilized eggs was attributed to the males guarding mated females from subsequent mating attempts by other males. What additional behavior contributed to successful production of fertilized eggs?
A. As opportunistic hermaphrodites, smaller males were able to mate and reproduce as females. B. Smaller males distracted larger males for more than 40 minutes, past the viability of their sperm, and then the smaller males mated with the females. C. The sparse population density of Sepia apama cuttlefish results in lower but equal reproductive successes among smaller and less aggressive males. D. Smaller, less aggressive males used mimicry of females to approach guarded females repeatedly to mate. E. All of the answer choices are correct.
___ are a type of internal signal molecule used in controlling the cell cycle.
Fill in the blank(s) with the appropriate word(s).
The first land vertebrates were the ________
Fill in the blank(s) with correct word