The answer to this would be D: physical components of the environment, such as rocks and sand. The word "biotic" mean all the living organisms within an ecosystem such as plants and animals.
Activators and repressors are transcription-control elements that are found in eukaryotic organisms. These elements function during the process of transcription, where a DNA molecule is coded onto a RNA molecule for it to be sent to ribosomes outside of the nucleus and then polypeptide chains are produced from it.
The activators and repressors control which proteins are made, which means that they can either hinder or promote certain functions in the cells of the body. Therefore, even though all of the cells have the same set of DNA, some are able to produce HCl, while others produce other substances such as insulin.
What sample are you talking about?
Effector, control center, receptor, and feedback are all involved in maintaining homeostasis. Lack of change is NOT involved in maintaining homeostasis.<span />
