<span>The correct answers are zygote and fetus. This is correct because the initial joining of the sperm and the egg is called the zygote. The zygote is the first step in prenatal development that grows and transforms over months into the final form, a fetus. The fetus is the last form of the zygote prior to birth.</span>
        
             
        
        
        
Cell membrane is a thin line.it controls the movement of materials into and out of the cell. it is partially permeable,that is,it allows only certain materials to pass through.
        
             
        
        
        
As viruses cannot reproduce by themselves, they depend on the host cells that they infect to reproduce
        
                    
             
        
        
        
A population that has been isolated, especially a smaller one, could have a high level of homozygosity and therefore not a lot of genetic variation. Gene flow between such populations can increase the level of heterozygosity, and therefore up genetic variation.
        
             
        
        
        
Meiosis is used to to make sex cells.
Mitosis is used to make regular cells for you body.