Sister chromatids have different alleles although carry same genes on same loci. So if it doesn't happen so, like if there are same alleles on sister chromatids then there is a problem in its formation. i.e., male and female alleles haven't contributed equally ( may be an error during their segregation process ). And obviously it doesn't happen in a real cell so we must understand this point. Because normally whenever it happens there's one half from the male and one half  from the female. (i.e. maternal and paternal alleles contribute equally).
 I hope you get the answer!!!
 
        
             
        
        
        
Answer:
DIFFUSION 
Explanation:
Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.
 
        
             
        
        
        
It is regulated by a <span>metabolic rate b serum glucose levels</span>
        
             
        
        
        
Answer: Rocky debris, primarily from the impactor and some of Earth's outer layer, was hurled out into orbit around Earth. 
Hopefully this helps