The transcription of a gene is controlled by a transcription factor binding either glucose or lactose. When there is 0.2 mM of either glucose or lactose in the cell, the gene is transcribed at about 10% of the maximum. When there is more than 2 mM glucose in the cell, the gene is fully induced. However, when there is 2 mM lactose in the cell, the amount of transcription is approximately half of the maximum. At 40 mM of either glucose or lactose in the cell, the gene is fully induced. The transcriptional regulation is likely:

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.