The Cambrian period I think
A water molecule consists of three atoms; an oxygen atom and two hydrogen atoms, which are bond together like little magnets.
An iron pot is made up of only one substance, iron. Iron is an element classified as a transition metal
Iron. Elementsare pure substances that are made up of one kind of atom. Pizza is not an element because it is a mixture of many substances. Water is a pure substance, but it contains two kindsof atom: oxygen and hydrogen.
Answer:
The answer is B an open system allows energy and mass to move in and out of it
Hope it helps
Each enzyme's active site is suitable for one specific type of substrate – just like a lock that has the right shape for only one specific key. Changing the shape of the active site of an enzyme will cause its reaction to slow down until the shape has changed so much that the substrate no longer fits.