Answer:
a combination of large groups of people, and they are all travelling- which increases the spread.
Answer:
You have not consumed lactose from dairy recently
Explanation:
According to the diagram, there is a represssor element in the regulatory region of the operon. This repressor is blocking the RNA polymerase, that is bound to its promoter region upstream of the genes, from transcription. The repressor is mostly the lac repressor that switches of the operon in the absence of lactose.
External Stimulus is the answer
Cells get nutrients from their environment, but where do those nutrients come from? Virtually all organic material on Earth has been produced by cells that convert energy from the Sun into energy-containing macromolecules. This process, called photosynthesis, is essential to the global carbon cycle and organisms that conduct photosynthesis represent the lowest level in most food chains (Figure 1).