Question: What is evidence that the phrase form follows function applies to biology? Need Assignment Help? The covalent bonds that connect the two strands of deoxyribonucleic acid (DNA) keep the double helix in its shape. A protein must be folded correctly to be able to perform its biological job. Proteins are constructed so that they can change their shape as needed to perform more jobs. A protein is folded into a required shape no matter what order the amino acids are assembled.