Answer: The lac operon is an inducible operon that is activated in the presence of lactose.
An operon is a unit of genes which are controlled by the single promoter and operator sequence. It consists of a regulatory gene, promoter, operator, and structural genes.
Lac (lactose) operon consists of three structural genes namely lacZ, lacY, and lacA. These genes are transcribed and translated to produce specific enzymes used for lactose metabolism.
It is called as inducible operon because lactose acts like an inducer as its presence induces the transcription process. The lactose is first converted into allolactose which then binds to repressor (synthesized by regulatory gene). In this way, it makes the repressor inactive and therefore allows the transcription of structural genes.
Answer:
False
Explanation:
Viscosity is a property of liquid that has resistance between liquid molecules. Those liquids having strong force of attraction between their particles has a viscosity whereas those liquid substances have weak intermolecular force of attraction between the particles has low viscosity. For example, water has low viscosity as compared to honey.
Most fish (especially the "Bony fish") achieve neutral buoyancy through a sac called the swim bladder in there body of which is filled with air, not much but it'a just enough to keep then a float. The fish can control this organ, and using that they can fill or release air to allow them to rise or sink.
Cartilaginous fish however, do not have a swim bladder.
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This process is called photosynthesis.