For E. coli cells, the sugar lactose acts as an inducer. In general, an inducer:
A: binds to the promoter and prevents the repressor from binding to the operator.
B: stimulates the synthesis of the needed enzyme(s).
C: binds to the operator and prevents the repressor from binding at this site.
D: inhibits the synthesis of the needed enzyme(s).
E: is the same as a promoter.
Answer: B: stimulates the synthesis of the needed enzyme(s).
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Indicate whether the statement is true or false
Which is not true about enzymes?
A. Enzymes are found in all cells. B. Enzymes can be denatured by heat and other agents. C. Enzymes participate in the cell's chemical reactions. D. Enzymes are catalysts. E. Enzymes have high-energy bonds between phosphates.
Which of the following series is arranged in the correct sequence for nitrogen fixation and its subsequent use?
A. atmospheric nitrogen; production of ammonia; use of bacterial nitrogenase; synthesis of proteins; conversion by plants or algae B. atmospheric nitrogen; use of bacterial nitrogenase; production of ammonia; conversion by plants or algae; synthesis of proteins C. atmospheric nitrogen; production of ammonia; use of bacterial nitrogenase; conversion by plants or algae; synthesis of proteins D. ammonia; conversion by plants and algae; production of atmospheric nitrogen; use of bacterial nitrogenase; synthesis of proteins E. atmospheric nitrogen; use of bacterial nitrogenase; conversion by plants or algae; production of ammonia; synthesis of proteins