40. Which one-letter symbol represents the amino acid lysine? (A) K (B) L (C) R (D) S

5. Which of the following statements is INCORRECT for retroviruses? (A) They are enveloped RNA virus. (B) They encode reverse transcriptase and replicate through a DNA intermediate. (C) Some of them produce tumors in the infected animals. (D) Retroviruses include human immunodeficiency virus (HIV) which primarily infects CD8 T cells.