When amino acid tryptophan is readily available on the growth media, bacteria do not have to synthesize this molecule. Genes controlling this mechanism are under control of
A. A reproducible operon
B. An inducible operon
C. Catabolic repression
D. Global regulation
E. A repressible operon
Ans: E. A repressible operon
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Which one of the following ribosomal subunits has three different pieces of rRNA in it?
A. 30S B. 40S C. 50S D. 60S
Heavy metals in contaminated soils can be taken up by hyper-accumulating plants. Lead and cadmium taken up this way are often accumulated in the plants'
A. rhizomes. B. trichomes. C. stomates. D. sclerenchyma. E. root nodules.
Which of the following is a true statement about glycogen?
a. Glycogen is made and stored in the liver and muscle. b. Glycogen is a long-term energy storage molecule. c. Glycogen helps cell membranes stay flexible. d. Glycogen is a precursor of steroid hormones.
Cytochromes contain a heme group similar to that in hemoglobin. The iron atom (Fe) in the center of the group can be oxidized and reduced. If someone was suffering from iron deficiency anemia, what stage of cellular respiration would be most affected?
A. glycolysis B. the electron transport chain C. fermentation D. the Krebs cycle