Gram-positive bacteria turn dark purple when a crystal violet stain is applied and then rinsed with the appropriate chemicals. Gram-negative bacteria have an outer membrane that doesn't absorb the violet color, so they turn pink instead.

A student wants to determine whether two bacteria strains in a petri dish are gram-negative or gram-positive. The teacher provides the appropriate chemicals. Which additional tools would be most useful?

A electron microscope, dropper, and computer monitor
B water, magnifying glass, petri dish, pencil and paper
C

Question

Gram-positive bacteria turn dark purple when a crystal violet stain is applied and then rinsed with the appropriate chemicals. Gram-negative bacteria have an outer membrane that doesn't absorb the violet color, so they turn pink instead. 

  

A student wants to determine whether two bacteria strains in a petri dish are gram-negative or gram-positive. The teacher provides the appropriate chemicals. Which additional tools would be most useful? 
 
 
    A     electron microscope, dropper, and computer monitor  
    B     water, magnifying glass, petri dish, pencil and paper  
    C