A collection of ideas and beliefs that sound like science but not supported by evidence, such as bigfoot, is known as... theory
fact
pseudoscience
law

pseudoscience

Explanation:

In nature, some ideas, beliefs or knowledge are mistaken to be scientific but in actual sense they are not supported by evidence using scientific method. These sorts of ideas are called PSEUDOSCIENCE. They do not follow the scientific method principles, hence, cannot be tested scientifically.

Pseudoscience is termed "fake science" as the name implies because they are brought forth as science in order to justify their claim but they are not in consistency with the scientific method. They lack the ability to be tested as false via experimentation. An example of pseudoscience as stated in the question is Bigfoot

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.