True. Epistasis describes a phenomenon in genetics where the effect of one gene's expression depends on the presence or absence of mutations in another gene. This means that one gene can "mask" or alter the expression of another, leading to complex interactions and non-Mendelian inheritance patterns.
While not all genes require another gene to be expressed (independent gene action), epistasis highlights the interconnectedness of genes and their influence on trait expression.
Therefore, the statement "Epistasis is when one gene depends on another gene for it to be expressed" is True.
