What are clouds of dust and gas from which a star first forms. they are pulled together by gravity into a spinning disc. the center of the disc becomes a star while the rest can be come a system of planets

The Nebula would be your answer, it is a cloud of dust and gas in outer space :)

chordata is the answer

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.