The membrane of gas vesicles is composed of:

Correct Answer: C

Rationale: The correct answer is C: proteins. Gas vesicles are gas-filled structures found in certain bacteria and archaea to provide buoyancy. The membrane of gas vesicles is predominantly composed of proteins that form a semi-permeable barrier to trap gas. Proteins are essential for the structure and function of gas vesicles. Triglycerides (A) are not typically found in membrane structures, phospholipids (B) are more common in cell membranes, and lipopolysaccharides (D) are typically found in the outer membrane of Gram-negative bacteria, not in gas vesicle membranes.

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: B

Rationale: Step-by-step rationale: 1. Bronchitis is characterized by inflammation of the bronchi, leading to coughing and mucus production. 2. Asthma involves inflammation and narrowing of the airways but is not specific to bronchi. 3. Emphysema is a lung disease involving damage to the air sacs, not specifically inflammation of bronchi. 4. Tuberculosis is a bacterial infection affecting the lungs, not primarily characterized by bronchial inflammation. Summary: Bronchitis is the correct answer as it specifically involves inflammation of the bronchi, while asthma, emphysema, and tuberculosis do not primarily exhibit this characteristic.

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.