Cross over is the first  way genes are shuffled to give rise to genetic diversity. Cross over takes place in sexual  reproduction.  The normal way that cross over occurs is chromosomes line up side by side and break off pieces of themselves, then trade those pieces with each other.
If they break the pieces at the same locus in the sequence of base pairs, the result is an exchange of genes called  genetic recombination and it ensures that the daughter cells produced  have a different genetic makeup from the parent cell and thus diversity occurs.
  
 
        
             
        
        
        
Answer: A group that closet matches characteristics
Explanation:
A representative sample is a group that closely matches the characteristics of its population as a whole. In other words, the sample is a fairly accurate reflection of the population from which the sample is drawn.
 
        
             
        
        
        
Answer:
 there are many.. 
Explanation:
wheel and axel are two type of forces in simple macine
 
        
                    
             
        
        
        
mid-oceanic ranges I believe. 
 
        
             
        
        
        
Multicellular organisms can be much larger and more complex. This is because the cells of the organism have specialised into many different types of cells such as nerve cells, blood cells, muscle cells all performing different functions.