What class of enzymes are involved in triggering events in the cell cycle?

Consider the last statement in the prompt: "people take such environmental factors into account in their choices when deciding where to live." do all people have a choice as to where they live? what factor plays a key role in this decision and may therefore play a large role in determining quality of life?

How can you approximate the number of calories required to keep you in energy balance?

Body systems are not completely independent they integrate and work together describe one example of the integration between body systems