The highest elevation at which trees can grow is
A. the Arctic tree line.
B. usually determined by salt spray.
C. determined by temperature.
D. the Antarctic tree line.
E. usually determined by oxygen concentration in the atmosphere.
Answer: C. determined by temperature.
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Post-translational regulation of an enzyme's activity, such as glutamine synthetase, can be finely controlled at varied levels due to
A) the varied strengths metabolite-regulating compounds can have with the enzyme such as hydrogen bonding, covalent bonding, and van der Waals attractions. B) having multiple independently functional subunits. C) the structural strength enzymes have once properly folded compared to short-lived and easily degradable transcripts during translational regulation. D) weak chemical modifications of the enzyme rather than harsh protein-protein or protein-DNA interactions.
What is the purpose of the cilia and flagella of cells?
a. They generate the cell’s metabolism. b. They provide movement for the cell. c. They help maintain homeostasis. d. They generate cell signaling. e. They contract muscles
RNA is ____ and contains the nitrogenous base ____, which is absent in DNA
a. single-stranded; thymine b. double-stranded; uracil c. single-stranded; uracil d. double-stranded; thymine e. single-stranded; cytosine
The first step in the formation of urine is the
A) secretion of hydrogen ions into the kidney tubules. B) formation of filtrate that enters Bowman's capsule. C) secretion of urea into the renal pelvis. D) reabsorption of nutrients by Bowman's capsule.