What makes a theory change over a period of time

Une théorie change avec les avancées scientifiques, les avancements culturels et les changements de point de vue de la société.

A theory is simply something that is approved by a large amount of people with research. A theory theoretically can never become a law because in order to become a law, It would have to be proven without a doubt. Meaning that in order to change over time, the only thing that could possibly change is the amount of evidence and people that support it. For example, Thermodynamic Laws are proven and can be researched without a doubt. However, Darwin's Theory of Evolution will likely never be a law because it can not be hunkered down and completely proven.

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the water molecules are transferred from the roots to the stem or top parts of the tall tree because of important properties of water which are adhesion, cohesion and capillary action. cohesion is the property of water molecules keeps water molecules in a combined state by sharing of bonds between them at the atomic level. adhesion allows the interaction of water molecules with other substances or substrate. adhesion will cause the attachment of water molecules to the wall of the vessel (xylem) of the plant. capillary action occurs when the adhesive force to the vessel wall is stronger than the cohesive force between water molecules. capillary action mimics the transfer of water from a tube or pipe. in this way water utilizes its property to transfer water from down to top level of the plant.  

where in your body is there an enzyme that does function at a high or low ph? what is the name of that enzyme and its function?