Question

which of the three plates seen in the image would represent a successful quadrant streak method?

a. plate a
b. plate b
c. plate c

Explanation:

Analyze the purpose of a quadrant streak

The goal of a quadrant streak plate is to progressively dilute a bacterial sample across four quadrants to obtain well-isolated, distinct individual colonies (Colony Forming Units) in the final quadrants.

Evaluate each plate

• Plate A: Shows heavy, confluent growth in all streaked areas with no isolated single colonies.
• Plate B: Shows extremely dense growth covering almost the entire plate, with no distinct, isolated colonies.
• Plate C: Shows a clear dilution gradient, transitioning from dense growth in the initial quadrants to clearly separated, isolated individual red colonies in the central/final quadrant.

Answer:

• Plate A
• Plate B
• Plate C (Correct answer)