A plant can survive without water, but not for very long. Humans
can survive a day or two without water, but like all life, to have
a long life we need water.
Depends on the plant - some plants store water for when it is
not available then they can go months without water. A seed cannot
grow into a plant though without water or moisture.
Also, some plants can live in Salt water and other places where
you'd think it's impossible.