The phrase "are apparently necessary" is correct and usable in written English.
It can be used when discussing something that seems to be required or essential based on available information or observations.
Example: "The changes to the policy are apparently necessary to ensure compliance with new regulations."
Alternatives: "seem to be essential" or "appear to be required."
But, while some institutions are apparently necessary for the smooth functioning of the market, others are an impediment.
Thus, the movements of the eye are apparently necessary to allow the contours of the image to fall on a new set of rods and cones at repeated intervals; if this does not occur, the retina adapts to their stimulus and ceases to send messages to the central nervous system.
Since transcription activation was not observed when BoxA was inactivated by mutations (PhilD*), half-saturating Fur·Mn2+ concentrations are apparently necessary for transcription activation of the hilD promoter in vitro.
(The apostrophe was apparently necessary to "avoid a simple pun", although what that pun was has never been explained).
As for Simenon's compulsive sexual activity, it was apparently necessary to overcome his mother's coldness to him.
The function of vitamin A remains to be clarified, but it is apparently necessary for proliferation of cartilage and bone growth.
Well, a little hype is apparently necessary to justify an hourlong report on the networks these days, and this one offers interesting insights and asides on how uncivilly the abortion war is being fought in this voting season.
"It is apparently necessary for me to state once again — not what kind of church I believe in, for that should be important only to me, but what kind of America I believe in," he said that day.
There would always be functional justifications for what often seem like purely visual features; in the case of the Pompidou Centre, it was apparently necessary to have the lifts, tanks, pipes and other services outside of the building to create the space for large, flexible rooms that could hold wide varieties of artworks.
But as yet another brace of TV documentaries is screened featuring intrepid Englishmen trawling Scotland and prodding its inhabitants in search of referendum data, it becomes difficult not to feel like a lab rat – a common enough species about whose neurological functions more information is apparently necessary, to understand why it might want to alter the boundaries of its natural habitat.
Such an expansion of the term opera was apparently necessary to accommodate the unfortunate dearth of musical documents to support their thesis.
