| Actually, yes, many scientists believe that a sentient species requires to be bipedal, and have binocular vision in order to adapt best to its enviroment. It's all about tools and depth perception. |
Being bi-pedal (or any-pedal) is only useful for an organism that lives at a solid-gas boundary, like we do at the surface of the Earth. An organism that lives in a thicker fluid environment, such as a liquid ocean or denser gaseous layer such as those found on gas giants, has wildly different locomotional needs. Furthermore, being bipedal has absolutely nothing to do with the operation of tools. Neither do hands. Don't forget, tools are evolved to suit the physiology of the users, not the other way around.
Binocular vision, though, is likely to be more fundamental than any limb configuration. An intelligent species that evolved without the ability to accurately estimate distance in real time would be remarkable. Such a species would fail to be a successful predator and would instead be spectacularly successful prey. That said, the use of the word 'vision' reveals an assumption that eye-like organs would evolve spontaneously in extraterrestrial environments. It also implies that environments opaque to photons or devoid of light would not support life, an assumption that we don't need to look past Earth to disprove (though no such life forms on Earth ever evolved intelligence, as far as we know). It also assumes that triangulation by vision is the most efficient and effective way to estimate distance, which makes one wonder why echolocation evolved in bats and radar is used in the military. However, triangulation through binocularity has the distinct advantage of being passive.
Finally, gross distinctions like 'plant' and 'animal' are highly terracentric. With our sample size of one (1) ecosystem for extrapolation, the assumption that there is anything else in the universe that meets our definition of a 'plant' is hugely defeasible.
