Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Ex Input:
Insulin is made up of two polypeptide chains.

Ex Output:
Insulin is made up of how many polypeptide chains?


Ex Input:
Terrestrial biomes are associated with land, while aquatic ones are associated with water.

Ex Output:
Terrestrial biomes are associated with land, while aquatic ones are associated with what?


Ex Input:
Vertebrata are characterized by the presence of backbone.

Ex Output:
Vertebrata are characterized by the presence of what?