It is an indicator of poor air quality from air pollution. This pollution is most often ozone or particulates. Typically it indicates that the air is unhealthy for children, the elderly, and sensitive groups.
I believe a biotic factor because i was taught it was alive it still counts and also houses other organisms
Answer : Passive transport mechanism
Explanation: Passive and Active transport mechanisms are the two types of transport mechanisms by which molecules move in and out of the cell membranes. Passive Transport mechanisms do not require energy from cells. The movement of the molecules from High to Low concentration requires no energy. E.g. Osmosis, simple and facilitated diffusion.
RAS is a very important protein that belongs to a class of protein referred to as GTPases and plays a crucial role in switching on pathways that control cell growth, proliferation, apoptosis and differentiation and migration. For RAS to become inactive it must hydrolyze GTP to GDP which slows down the process of cell proliferation. Mutation in one copies of RAS will result to cancer because the mutated copy will permanently attach to GTP and remain in activated form which will lead to uncontrollable cell division and hence development of cancer.