Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Regulation of transcription in prokaryotes typically involves operons. An operon is a region of DNA that consists of one or more genes that encode the proteins needed for a specific function. The operon also includes a promoter and an operator. The operator is a region of the operon where regulatory proteins bind. It is located near the promoter and helps regulate transcription of the operon genes. Answer: operon

Answer: Which region of dna consists of one or more genes that encode the proteins needed for a specific function?

Question: Passage: A variable is a factor that can change over the course of an experiment. Independent variables are factors whose values are controlled by the experimenter to determine its relationship to an observed phenomenon (the dependent variable). Dependent variables change in response to the independent variable. Answer: independent variables

Answer: The values of which factors are controlled by the experimenter over the course of an experiment?

Question: Passage: You can see an example of a negative feedback loop in Figure below . It shows how levels of thyroid hormones regulate the thyroid gland. This loop involves the hypothalamus and pituitary gland as well as the thyroid gland. Low levels of thyroid hormones in the blood cause the release of hormones by the hypothalamus and pituitary gland. These hormones stimulate the thyroid gland to secrete more hormones. The opposite happens with high levels of thyroid hormones in the blood. The hypothalamus and pituitary gland stop releasing hormones that stimulate the thyroid. Answer: hormones

Answer:
Low levels of thyroid hormones in the blood cause the release of what by the hypothalamus and pituitary gland?