"tryptophan self-controls its synthesis." justify this statement.
a. if a lesser amount of tryptophan is present in a cell, tryptophan acts as an inducer and binds to a repressor, leading to the synthesis of enzymes required for its production and thus its synthesis.
b. if an excess amount of tryptophan is present in a cell, tryptophan acts as a promoter, preventing the further synthesis of necessary enzymes for its production and thus its synthesis.
c. if an excess amount of tryptophan is present in a cell, tryptophan acts as a co-repressor, preventing the further synthesis of necessary enzymes for its production and thus its synthesis.

Option C, If an excess amount of Tryptophan is present in a cell, Tryptophan acts as a co-repressor, preventing the further synthesis of nessary enzymes for its production and thus its synthesis.

Explanation:

When level of tryptophan is high it attache to the trp repressor  and this duo together act as a repressor. Binding of tryptophan changes the shape of the repressor and thus convert it into the active DNA binding form. This duo of tryptophan and trp repressor attaches with the operator and block binding of RNA polymerase to the promoter. In this way further transcription of the operon is prevented.

Hence, option C is correct

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

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a researcher conducts an experiment on the secretion of a particular hormone in mice. scientists inject mice with a substance that stimulates the production of the hormone. the scientists then test the levels of hormones produced by the mice. the tool used to measure the hormones consistently detects the levels at 10 points lower than the actual hormone levels in the mice. this tool makes measurements, but the measurements aren't .

explanation:

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