Advanced Placement (AP) Biology Practice Exam

What is the role of local regulators in cellular processes?

1. They influence cells far away

2. They affect nearby cells

3. They act only on the hormone-producing cells

4. They are involved in signal transduction across the body

The correct answer is: They affect nearby cells

Local regulators play a critical role in cellular communication by affecting nearby cells. These are often signaling molecules that act within a localized area, meaning they generally diffuse over short distances to reach target cells. This is particularly important in processes like tissue repair, inflammation, and development, where precise and localized signaling is necessary for coordination among cells that are in close proximity. For instance, local regulators can include substances like neurotransmitters, growth factors, and cytokines, which are released by one cell and can specifically influence the behavior of adjacent cells. This direct communication allows for rapid responses within tissues without sending signals throughout the entire body, as would be the case with systemic hormones. In contrast, options that imply influencing cells far away or a broad range of cells throughout the body mischaracterize the primary function of local regulators, which is focused and region-specific. Other options, such as those involving only hormone-producing cells or general signal transduction across the body, do not accurately represent the role of local regulators, as they operate in more constrained and specific contexts.