Relative dating best helps determine fossil age. It's where layers of sedimentary rock and fossils pile up on top of each other; the oldest fossils being in the bottom layer and the youngest in the top.
        
             
        
        
        
I think protonion is a subatimic particle
        
             
        
        
        
I remember the secondary structure by visualizing it. Understand that primary structure is just the order of the amino acids. The tertiary structure is the 3dimensional configuration of the whole protein molecule with multiple interactions guiding its fold (disulfide bonds, ionic interactions, hydrogen bonds, van der walls). Secondary structure is a step towards the conformation of the protein where it is made up of either alpha-helices or beta-pleated sheets. The alpha helices look like a spiraling staircase while the beta-pleated sheets look like a repetition of long loops. These two structures hold itself by hydrogen bonds.
        
             
        
        
        
The answer would be : <span>It is a well supported explanation which cannot become a law.
A law and a theory are different you know. In fact, the law is universel. This applies for everything unlike a theory which explains in particular why something is happening.
Any doubts ?
Hope this helps !
Photon</span>
        
             
        
        
        
 V₍t₎ = 2πr/t  
time is taken