Neither!
Do not italicize:
Scientific names for phylum, class, order, and family, but use initial caps.
Scientific names are composed of the GENUS name, which is capitalized, and the species name, which is always lower case. The entire scientific name is ALWAYS underlined or italicized.
No it should not be italicized. If you are referring to a specific train then it should be capitalized. If the name of the train appears in a title of an article, book etc then it should be italicized in that case.
Not usually, but their initial letters are capitalized as for any title, such as American Centennial World Exposition.
It is not recommend that the title of a PowerPoint be italicized. It is recommended that the author or originator of the presentation be italicized.
No, it is not necessary to italicize airplane names. Proper names for specific models of planes such a the Boeing 787 and the Airbus A380, or an airline name such a Southwest Airlines and Jet Blue Airways are proper nouns and should be capitalized.
Yes, journal names should be italicized in academic writing to indicate that they are titles of publications.
No, website names are not italicized in APA format.
Yes, article names are italicized in APA format.
No, organizations are not required to have their names italicized in official documents.
By convention the binomial Latin names are always italicized.
Yes, in APA style, organization names are not italicized.
Yes, gene names are typically italicized in scientific papers to distinguish them from regular text.
Yes, journal names are typically italicized in academic writing to distinguish them from the rest of the text.
No, McDonald's does not need to be italicized.
Yes, article names should be italicized in academic writing to indicate that they are titles of works.
Yes, orders do not need to be italicized. Orders can be written in regular font.
In APA format, website titles do not need to be italicized.