Answer:
B
Explanation:
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Answer: Osmosis is the movement of water or other solvent through a plasma membrane from a region of low solute concentration to a region of high solute concentration, tending to equalise the concentrations of the solutes. Osmosis is passive transport, meaning it does not require energy to be applied.
Examples of osmosis in daily life include plant cells soaking up water, skin soaking up water, and slugs reacting to salt.
Exploring the city with trolley cars and many hills. This city is San Francisco, CA.
Trolley cars or cable cars were introduced in 1873 to enable locals to contend with many hills the city is built on. Now, tourists ride the cable cars and will be given a tour of the city.
Answer: A
Explanation:The Trp operon is responsible for synthesis of the amino acid trytophan when it is not available in the cellular environment.
When the tryptophan is plentiful, a repressor protein binds to two molecules of tryptophan.
Thiss repressor-tryptophan complex binds to the trp operator. This binding prevents the binding of RNA polymerase, so the operon is not transcribed, and no new trptophan is produce.
On the other hand, when tryptophan levels are reduced, the inactive repressor will not bind the tryptophan operator so the operon is transcribed.
Regulation of the trp operon is determined by the concentration of tryptophan; when adequate tryptophan is present in the growth medium, there is no need for tryptophan biosynthesis.
Transcription is turned off when a high concentration of tryptophan is present, and is turned on when tryptophan is absent. The regulatory signal is the concentration of tryptophan itself.
Therefore in the absence of tryptophan, the inactive repressor cannot bind trpO, so operon gene transcription occurs.
