Which group is incorrectly paired with its description?
diatoms - important producers in aquatic communities
red algae - acquired plastids by secondary endosymbiosis
apicomplexans - parasites with intricate life cycles
diplomonads - protists with modified mitochondria

Red algae - acquired plastids by secondary endosymbiosis

Explanation:

Red algae are believed to have undergo a primary endosymbiosis event. Then a second endosymbiosis event created a large group known as heterokonts.  During the primary endosymbiosis event red algae acquire their plastids.

"griffith's experiment discovering the "transforming principle" in pneumococcus bacteria. griffith's experiment, reported in 1928 by frederick griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation." - griffith's experiment.