Question

every ____ gene typically contributes something to phenotype.
○ additive
○ nonadditive
○ recessive
○ x - linked

Explanation:

Additive genes are those where each allele contributes a small, additive effect to the phenotype. Nonadditive genes involve interactions like dominance or epistasis, so not every nonadditive gene contributes independently. Recessive genes only show their effect when homozygous, so not every recessive gene contributes to the phenotype in all cases. X - linked genes are related to sex - linkage and don't have the property of every such gene contributing to the phenotype in the same additive way. So the correct answer is the option with "additive".

Answer:

A. additive