For the inducible lac operon to be turned on, the

a. lactase (enzyme) must not be in excess.
b. substrate (lactose) must be absent.
c. substrate must be present and bind the repressor protein.
d. RNA polymerase must be blocked from transcribing the genes.


Answer: c. substrate must be present and bind the repressor protein.

Biology & Microbiology

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Fill in the blank(s) with the appropriate word(s).

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Indicate whether the statement is true or false

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Tightly curled hair is caused by a dominant autosomal gene in humans. If a heterozygous curly-haired person marries a person with straight hair, what phenotypes (and in what proportions) are expected in the offspring?

What will be an ideal response?

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Fermentation takes place in absence of carbon dioxide.

a. true b. false

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