The ability to roll the tongue (r) is determined by a dominant gene while the recessive gene results in the inability to roll the tongue (r). a man and his wife can both roll their tongues and are surprised to find that their son cannot. explain this by showing the genotypes of all three persons.

the truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey.

it would lead to upper respiratory infections and pneumonia.