The longest-living trees in the world are a species of
a. angiosperm
b. cycad
c. gymnosperm
d. fern

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.

this protocol provides a detailed procedure for co-immunoprecipitation (co-ip) to identify protein–protein interactions.