The E. coli lac operon encodes three genes. These genes ____
a. cleave lactose into glucose and galactose, produce transacetylase, and actively transport lactose into the cell
b. encode an enzyme that cleaves glucose, a transport protein for active transport, and a transacetylase enzyme
for solubilizing lactose in the cytosol
c. encode an enzyme that cleaves lactose, a transport protein for active transport of lactose, and a transacetylase
enzyme whose function is unknown
d. catalyze the synthesis of lactose from glucose and galactose, produce transacetylase, and actively export
lactose from the cell
e. directly interact with the Lac repressor and initiate their own transcription
ANSWER: c
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Erwin Chargaff discovered that DNA contains equal numbers of adenine and thymine bases and equal numbers of cytosine and guanine bases. Which hypothesis would this have most likely led to?
A.) DNA might be in the form of a helix. B.) There might be some kind of symmetry in the DNA molecule. C.) DNA is not the only molecule involved in the passing on of hereditary traits. D.) Guanine and cytosine have very different structures than adenine and thymine.
Transposons may leave a cell by incorporating themselves into a plasmid
Indicate whether this statement is true or false.
In the Gulf of Mexico, red tides caused by the dinoflagellate Karenia brevis cause massive fish kills as well as respiratory problems in humans. As an environmental scientist, what would you suggest concerned citizens do to help prevent these red tides?
A. Encourage sustainable fishing B. Participate in beach cleanup efforts C. Purchase fuel-efficient vehicles D. Reduce fertilizer use on lawns and gardens E. Decrease the amount of artificial light in coastal areas
In 1938, scientists found a population of coelacanths in the Indian Ocean. This fish species is considered a "living fossil" and appears not to have changed morphologically for 80 million years. This discovery supports the ________ model of evolution.
A. punctuated equilibrium B. gradualism C. common descent D. adaptation E. natural selection