1-Explain how homozygous and heterozygous genotypes are expressed in the phenotype of autosomal dominant and recessive traits or disorders. 2-Explain the chances an autosomal dominant and an autosomal recessive traits of being transmitted to the next generation as per pedigree or Punnett square 3-Explain how a pregnant woman should prevent congenital anomalies of the baby potentially caused by teratogenic agents. 4-State the etiologic and risk factors of chromosome numeric disorders, especially Down's syndrome .