Question

Georgia O'Keefe was an American painter from Wisconsin. Whose detailed close-ups of flowers brought her world renown.

Answer 1

There should be a comma between the words 'Wisconsin' and 'whose'

because since there is a peiod, the senences read
georgia o'kefe was an american painter from wisconson, meaning: georga o'keef, american, from wisconson

second one

whose detailed  close-ups of flowers brought her world renown
this is a clause, the two sentances should be joined with a comma because theh though continues

the sentances should read:
"Georgia O'Keefe was an American painter from Wisconsin, whose detailed close-ups of flowers brought her world renown."