A monohybrid cross involves the inheritance of a single trait, whereas a dihybrid cross involves the inheritance of two traits at the same time.

Quick Scoop

  • In a monohybrid cross, organisms differ in one character only (for example, seed color in peas). The classic F₂ phenotypic ratio for a simple Mendelian monohybrid cross is 3:1.
  • In a dihybrid cross, organisms differ in two characters simultaneously (for example, seed color and seed shape). The classic F₂ phenotypic ratio for a simple Mendelian dihybrid cross is 9:3:3:1.

So, the correct description is:

A monohybrid cross tracks a single trait, while a dihybrid cross tracks two traits at the same time.

TL;DR: One trait = monohybrid; two traits = dihybrid. Information gathered from public forums or data available on the internet and portrayed here.