33% is the unknown concentration of the tube.
Explanation:
Concentration of stock of windex = 50%
concentration of bacteria = 500 microliter
nutrient broth = 1000 micro litre +500 microlitre of windex
concentration of bacteria is the volume of bacteria present in nutrient broth culture. 
total volume in the tube is 1000
50% is the concentration of tube of bacteria and broth before adding windex.
After adding windex of 50 % concentration and the volume is 500 microliter which is only 250 microliter of windex rest is water.
33% is the concentration of the tube, which means it has 33% of bacteria in 1500 ml of solution.
 
        
             
        
        
        
Answer:
the reproduce by putting the male representative organ in the female reproductive organ
 
        
             
        
        
        
Answer:A.) True
Explanation:
E.Coli would be a good model organism to study how the cell membrane controls movement of substances in and out of cells because  it a eubacteria .Eubacteria characteristics include the ability to allow the movement of molecules across its membrane once a proton gradient is established , The membrane also has permeability enhancing properties that allow for the easy movement of substances.
 
        
             
        
        
        
Answer:
option B) The oxygen end of the molecule has a partial negative charge and the hydrogen end has a partial positive charge.
Justification:
The electronegativity of an element accounts for its relative ability to attract electrons.
Being oxygen more electronegative than hdyrogen (the electronegativity of oxygen is 3.44 while the electronegativity of the hydrogen is 2.20), the electron density will be displaced toward the oxygen, letting it with a partial negative charge and the hydrogen with a partial positive charge.
Finally, since the charge is not symmetrical distributed around a center of the molecule, the molecule ends being polar.