Identify explanatory and response variables

Identify the independent and dependent variables in each source situation:

1. Investigate whether increased calcium intake would help prevent osteoporosis.
2. Investigate how the concentration of an injected drug in the bloodstream varies with time.
3. Investigate the time taken to complete a chemical reaction when different amounts of catalyst are used.
4. Record air temperature and altitude at noon on a particular day at eight mountainous locations.
5. Tabulate the distances of seven cities from the capital and the corresponding railway fares.