Answer: C
Explanation:
For example, in trp-operon, an abundance of tryptophan. coli inhibits the expression trp-operon genes.
Trp operon is a negative repressible feedback mechanism
trpR gene is expressed continually at a low level
Characteristics should be in the blank
<span>Photochemical smog, created by the chemical reaction between sunlight, nitrogen oxides and volatile organic compounds is (e) generally worse during the winter months in part because of the increase in energy used to heat homes and other buildings.</span>
