A calico cat exhibits both the characters for orange fur and black fur. What kind of expression is this?

The correct answer is:

Co-dominance

• When the alleles of a gene do not follow the law of dominance, the case of codominance occurs.
• In the case of a calico cat both the alleles for black and orange fur express themselves without any blending.
• Other examples of codominance is the ABO blood grouping system.