Narrow annual rings in a tree indicate what environmental event?
a. Mild temperatures
b. Abundance of sunlight
c. Excessive flooding
d. Fire went through the community
e. Severe drought
e
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Water absorption depends primarily on
a. abscisic acid. b. cohesion-tension. c. the concentration gradient between soil and root. d. active transport. e. the potassium pump.
In essentially all organisms, the AUG codon codes for:a
the initiation of translation. b. the termination of transcription. c. the termination of chain elongation. d. the amino acid valine. e. a termination tRNA molecule
Some mutagens cause genetic changes that can be "corrected" by reexposing cells to the same mutagen. Other mutagens do not behave in this way. Provide one example of each of these two types of agents and describe the mutational changes caused in
Explain why some mutagens behave in one way, whereas others do not.
Beta-N-Methylamino-L-Alanine, or BMAA, is a glutamate receptor agonist produced by cyanobacteria. Since glutamate is an excitatory neurotransmitter, it is not surprising that BMAA is associated with neurological damage. Buildup of BMAA in fruit bats was hypothesized to cause neurodegenerative disease in islanders that fed on the bats. A recent study found high levels of BMAA in sharks, suggesting that consumption of shark fin soup is also dangerous. The researchers suggested that a secondary effect of BMAA may actually make these hazardous foods surprisingly desirable. What might this be?
A. Since BMAA contains alanine, it improves protein synthesis by providing this rare nutrient. B. Since BMAA is derived from cyanobacteria, it provides unique nutrients not found in the animal or plant kingdom. C. Since BMAA is a Glu receptor agonist, it promotes incorporation of Glu into proteins, and has health-promoting effects. D. Since BMAA is a Glu receptor agonist, it imparts a strong umami flavor that makes food more delicious.