One method of identifying specific chunks of DNA involves chopping up an entire strand of DNA and then inserting each chunk into a different bacterial cell. The bacterial cells divide into small colonies. Each of these colonies contains a different segment of the original DNA strand, so together they are known as a

select answer
DNA library
nucleic acid hybrid
polymerase chain reaction

he geneticist takes samples from these colonies and then exposes those samples to radioactively labeled fragments of DNA or RNA known as

select answer
probes
DNA libraries
primers

The correct answer is 4th option.

Negative feedback will stop the release of this hormone.

Negative feedback loop is responsible for down regulating the expression of a hormone in our body. Negative feedback loop is required to restrict the unnecessary wastage of our body's energy in producing a hormone when it is not even required. Once we have maintained the water balance in our body with the help of that hormone we don't require it anymore so we need a negative feedback loop to stop the synthesis of this hormone. Our body has to dedicate some energy in the production of any hormone (protein).  If negative feedback loop will not act once the water balance has been maintained, it will cause excessive hormone release unnecessarily which is not at all required.