What item ( food, plant, or disease ) do you think had the most impact as a result of the columbian exchange and why. -use complete sentences-

Disease had the most impact as the result of Columbian exchange because due to this exchange deadly diseases spread across all over the world with the travel and migration of people.

Columbian exchange was as exchange of plants, animals, humans, culture, disease, technology and other things to the Africa, America and many other countries. The Columbian exchange had negative as well as positive impact on both the continents.  

Impact on Europe:

This exchange benefited the old world with the introduction of "new world crops" such as corn and potatoes. This exchange had negative impact as well. The transmission of epidemics and African people into slavery were some of negative impacts of Columbian exchange.

Impact on America:

The technology helped in advancement in agriculture and food cultivation while the exchange of disease increased the mortality rate among the Americans.