Answer:
alle and the daphina cell 
 
        
             
        
        
        
Answer:
1.) Why does menstruation begin?
A.) Period happens because of changes in hormones in the body. 
2.) How long does the menstrual cycle usually last?
A.) the menstrual cycle lasts 21 to 35 days while bleeding between 2 to 7 days
<u>-TheUnknownScientist</u>
 
        
             
        
        
        
One long, single molecule of double stranded, helical, supercoiled DNA. In most bacteria, the two ends of the double-stranded DNA covalently bond together to form both a physical and genetic circle