Primary (spontaneous and externally induces) damages to genetic material frequently lead to heritable changes (gene mutations, chromosome aberrations and nondisjunction), which may cause cancer inherent and inborn diseases. It is suggested that primary damages may affect a phenotype until they are repaired or become mutations during inaccurate repair The alpha-test on the yeast Saccharomyces cerevisiae can answer the fundamental questions as the nature of primary damages that can be phenotypically manifested, their occurrence, conversion to each other and repair or conversion to heritable changes in genetic material.