Multiple choice

Which of the following is produced by the alpha-hemolytic colonies on blood agar?

  1. Zone of complete clearing

  2. No zone

  3. Zone of partial clearing (green)

  4. Brown colored zone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Alpha-hemolytic colonies produce zone of partial clearing on blood agar. Alpha hemolysis is caused by hydrogen peroxide produced by the bacterium, oxidising hemoglobin to green methemoglobin.

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