Unicellular organisms, cells perform all the basic actions and functions required for living like nutrition, respiration, reproduction etc.
In multicellular organisms, cells divide their tasks on the basis of "DIVISION OF LABOUR" to specialize in certain functions besides respiration etc. Like conduction in neurons, excitation in muscles, RBC production by bone marrow etc.
What they have in common is that they both have the same number of atoms. Hope this helps. :)
Properties of a compound is completely different from their elements.
Water is composed by hydrogen and oxygen.
For example, the boiling point of oxygen is - 183 °C and hydrogen is - 253 °C, meanwhile, water has a boiling point of 100°C
Another example is when you put a burning wooden splint into oxygen, it burns more brightly. Put it in hydrogen, you may hear a "pop" sound, or even explode when large amount of hydrogen. But if u put a burning splint in water, it goes off.
