Which of the following is NOT found in every nucleic acid?
a. ribose
b. phosphate group
c. purine
d. pyrimidine
e. uracil
E
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Anaerobic fermentation often provides CO2, which can be used by ________ as an electron acceptor for energy
A) acetogens B) methanotrophs C) methanogens D) acetogens and methanogens
Acclimatization is the process by which animals adjust to seasonal changes. Which example is least characteristic of
acclimatization? a. An endotherm entering torpor b. A horse’s coat thickening in winter c. A fish’s metabolic rate slowing d. A bear entering hibernation e. A lizard basking in the sun
It is possible for a repressor to negatively regulate the expression of an operon because:
A. the repressor-binding site on the DNA overlaps with the translation start site, thereby preventing the transcription. B. the repressor physically blocks where the activator should be binding on the operator region. C. one of the structural genes expressed in the operon negatively regulates the repressor. D. the repressor-binding site overlaps the promoter site of the operon, allowing it to physically block the binding of RNA polymerase. E. the repressor induces the expression of the inducer by binding to the promoter that comes before the inducer gene.
In 2012, scientists discovered that colonies of single-celled organisms can be found in high numbers in the human gut. Scientists are particularly concerned with the colonies that produce methane, as methane in the human gut can be linked to constipation
and irritable bowel syndrome (IBS). The scientists can classify these colonies as belonging to the domain A) Archaea. B) Bacteria. C) Eukarya. D) Protista.