Plaques are:

Correct Answer: A

Rationale: Plaques are clear areas caused by virus infection in a lawn of cultured cells. This is because viruses infect cells, causing cell death and lysis, which results in clear areas. Choice B is incorrect because stained areas are not typically associated with plaques. Choices C and D are also incorrect as they refer to virus and bacterial colonies, respectively, not plaques.

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.

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.