Answer:
1) Founder effect and genetic drift: Small colonizing population did not represent the original gene pool of the source population and was more likely to undergo genetic drift.
2) Natural selection 
Explanation:
Evolution of the population of the finches with larger beaks might have occurred due to one of the following mechanisms:
a) Founder effect and genetic drift: Since the size of the colonizing population was small, it did not carry all the genes and their alleles present in the gene pool of the original population. The small population size made it more likely to evolve by any chance event.  
b) Natural selection: The availability of different food types in the new habitat led to the natural selection of the larger beaks as the finches with larger beaks might have been able to better exploit the available food resources.  
 
        
             
        
        
        
The pair of characteristics that one must use to classify a fish is the presence of jaw and skeleton type. Agnatha fishes are also called jawless fishes and they lack bony skeletons. Cartilaginous fishes are composed of cartilage skeletons. Bony fishes have bony skeleton structures.
        
             
        
        
        
Copernicus' model: "Sun-centered," or "heliocentric"
Copernicus thought that the planets orbited the Sun, and that the Moon orbited Earth. ... Copernicus was correct about some things, but wrong about others. The Sun is not in the center of the universe, and it does move, as do the stars.
        
             
        
        
        
 The mosaic nature is due to the numerous proteins that
are entrenched in the phospholipids bilayer, fluctuate in shape, size and
patterns in the same way as the stones or tiles of a mosaic. 
the flexibility is due to individual phospholipids molecules which can move virtual
to one another and gives the membrane a flexible structure that is constantly
changing shape
hope it helps