1On a polypeptide, which amino acid cannot be phosphorylated?(A) serine (B) valine(C) threonine (D) tyrosine

11. Which description is false?(A) X-rays are hazardous because they cause DNA double-strand breaks, which are hard to repair.(B) an A to.G mutation is called a point mutation.(C) Human cells are used in the Ames test to determine the carcinogenic effects of chemicals.(D) Non-homologous end joining usually results in DNA mutations.