Cross between "Homozygous Dominant" & "Homozygous recessive" would result in offspring of phenotype 1:1:1:1. When linkage is not occurs!
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Answer:
true
Explanation:
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1. Testing only one variable
A controlled variable means its the one that stays the same. In a controlled experiment, it means there is only one manipulated, (changed) variable. 
        
                    
             
        
        
        
Very powerful microscopes were needed before cells could be observed in detail