Which of the following are not examples of a terminal electron acceptor in anaerobic respiration?

Correct Answer: D

Rationale: The correct answer is D: H₂. In anaerobic respiration, H₂ can act as a terminal electron acceptor, so it is not an incorrect example. Nitrate, hydrogen sulfate, and iron hydroxide are all examples of terminal electron acceptors in anaerobic respiration. H₂ is commonly used in microbial processes as an electron donor, not as a terminal electron acceptor. This is because H₂ is typically oxidized to produce energy, rather than accepting electrons.

Correct Answer: A

Rationale: The correct answer is A: DNA polymerase I. DNA polymerase I has both 5' to 3' polymerase activity and 5' to 3' exonuclease activity, allowing it to cleave DNA in the 5' to 3' direction. This enzyme can remove RNA primers during DNA replication by cleaving them in the 5' to 3' direction and replace them with DNA nucleotides. DNA polymerase II, III, and IV do not have the same exonuclease activity as DNA polymerase I, so they are not capable of cleaving DNA sequences in the 5' to 3' direction like DNA polymerase I.

Correct Answer: E

Rationale: I'm sorry, but it seems like there was a mistake in the question as there is no option E provided. However, the correct enzyme that excises incorrect nucleotides on the newly synthesized DNA is DNA polymerase III. DNA polymerase III has a 3' to 5' exonuclease activity that allows it to proofread and remove incorrect nucleotides during DNA replication. DNA gyrase is involved in DNA supercoiling, RNA primase synthesizes RNA primers, and DNA ligase seals nicks in the DNA backbone. DNA polymerase II is involved in DNA repair.

Correct Answer: A

Rationale: The correct answer is A: Calf intestinal phosphatase. This enzyme removes 5' phosphate groups from DNA molecules, preventing self-ligation of restricted plasmid vectors. This step is crucial in generating linearized vectors for downstream applications. Pyrophosphatase (B) hydrolyzes pyrophosphate bonds, not 5' phosphate groups. Phosphohydrolase (C) is a general term for enzymes that hydrolyze phosphoester bonds, not specific to 5' phosphate removal. Phosphate exonuclease (D) degrades nucleic acids by removing nucleotides from the 3' end, not the 5' phosphate group.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.