I can't really give you two paragraphs but one (and probably the biggest) thing was democracy. Democracy is the 'everyone gets a fair vote' and the Romans had originally started that system. After the Roman empire fell apart, the system was completely forgotten until the USA became its own country.
Another thing that we took from the Romans is archetecture. (<-- spelled wrong). Before buildings were built with steel, American's had to rely on the Roman columns, domes, and arches. Arches are great for distributing weight so that the building wouldn't collapse in on itself and so are domes. They spread the weight evenly so that you don't have to use massive pillars to hold the building up. But when steel began to be produced, the Roman architechture became more of a decorative thing because steel is a lot stronger and can support more weight.
Plasticity is an organisms ability to change physiologically depending on the environmental circumstances, it is the ability of an organism to change in response to an external stimuli by applying an appropriate physiological adaptive response.
