9.1 Inheritance

• The trait is always expressed in the phenotype if a dominant allele is present.
• The trait is only expressed in the phenotype if both alleles are recessive.
• Type O blood produces A and B antibodies.
• Type A blood produces B antibodies.
• Type B blood produces A antibodies.
• Type AB blood produces no antibodies.
• Type AB is the universal recipient as it will not trigger an immune response as it does not produce any antibodies.
• Why does each individual not have all of the alleles for blood group?

  Humans are diploid, so only express two alleles.
• Autosomal chromosomes are pairs 1 - 22.
• Sex chromosomes are pair 23, and they determine biological sex.