7.1 inheritance

• Genotype – all of the alleles that an organism carries on its chromosomes.Phenotype – observable characteristics of an organism which the result of the genotype as well as environmental factors.
• Dominant - only one single allele is required for a characteristic to be expressed in the phenotype - if there is 1 dominant allele this is known as heterozygous dominant (Tt) if the organism has 2 dominant alleles this is known as homozygous dominant (TT)
• Recessive - characteristic will only be expressed if there is no dominant alleles present - so there must be 2 recessive alleles for phenotype to be expressed (homozygous recessive - tt) 
• Monohybrid inheritance -  when a phenotype or trait is controlled by a single gene 

  Dihybrid inheritance - when two characteristics are studied and is determined by two different genes that are present on two different chromosomes at the same time.