Question

how would one interpret a petri dish with a single bacterial species that has small bacterial colonies growing near some contaminating mold and large bacterial colonies far away from the mold?
the mold is secreting a substance that destroys nearby bacterial cells.
the mold is secreting a substance that is slowing down the growth of nearby bacteria, but not causing them to burst.
the mold is supplying nutrients that encourage a wide range of bacteria to grow.
this is not a surprising observation that requires any kind of interpretation.

Explanation:

The observation shows small bacterial colonies near the mold and large colonies far from it. If the mold destroyed bacteria (option A), there would be no colonies near it. Option C is incorrect because only one bacterial species is present, and nutrients would not cause size differences by distance. Option D is wrong as the size difference requires interpretation. The size difference indicates growth inhibition (smaller colonies near mold) without complete destruction, matching option B.

Answer:

B. The mold is secreting a substance that is slowing down the growth of nearby bacteria, but not causing them to burst.