Question

The Ames II test uses auxotrophic strains of bacteria to detect base pair substitutions and frameshift mutations. The test identifies a chemical as a mutagen when:

A) The bacteria fail to grow.
B) Reversion to prototrophy occurs.
C) The frameshift mutations become permanent.
D) Base pair substitutions are repaired.

Answer 1

The Ames II test uses auxotrophic bacteria to detect mutations and identifies a chemical as a mutagen when reversion to prototrophy occurs.

Step-by-step explanation:

The Ames II test uses auxotrophic strains of bacteria to detect base pair substitutions and frameshift mutations. It identifies a chemical as a mutagen when reversion to prototrophy occurs. In this test, the bacteria are plated on a medium lacking a specific nutrient (histidine) which the auxotrophic bacteria cannot produce on their own. So, any mutation that restores the ability to synthesize histidine indicates that a mutagenic chemical is present.