Its called a microscope slide
        
             
        
        
        
Answer:
genes
Explanation:
The DNA that is present in every cell's nucleus is like a long double-stranded thread.
This long DNA contains various genes. Genes are DNA sequences that encode proteins to bring out the characteristic change in a body.
 
        
             
        
        
        
It is the disulphide bond. 
        
             
        
        
        
<u>arteries carry oxygenated blood and veins carry de-oxygenated blood.</u>
 
        
                    
             
        
        
        
Genetic variation can be caused by mutation ( which can create entirely new alleles in a population), random mating, random fertilization, and recombination between <span>homologous chromosomes during meiosis ( which reshuffles alleles whitin an organism's offspring). </span>