Emphysema is characterized by ______.

Correct Answer: A

Rationale: Rationale: A: Emphysema is characterized by the destruction of alveolar walls and loss of elasticity of the lungs, leading to air trapping and difficulty exhaling. This results in reduced gas exchange and airflow limitation. B: Bronchospasms are more commonly associated with conditions like asthma, not emphysema. C: Abnormal growth of epithelial cells is seen in conditions like lung cancer, not emphysema. D: Excessive mucus production is characteristic of conditions like chronic bronchitis, not emphysema. Summary: The correct answer is A because emphysema specifically involves the loss of elasticity of the lungs due to destruction of alveoli, leading to impaired airflow. Choices B, C, and D are incorrect as they describe features more indicative of other respiratory conditions.

Correct Answer: D

Rationale: The correct answer is D: Recombinant DNA. Recombinant DNA refers to the DNA molecule formed by combining DNA from different sources. In genetic engineering, this is created by inserting a foreign DNA fragment into a vector DNA, resulting in a new DNA molecule. Plasmid DNA (A) is a small, circular DNA found in bacteria. Vector DNA (B) is a carrier molecule used to transport foreign DNA into a host cell. Insert DNA (C) is the DNA fragment that is inserted into a vector. Therefore, choice D is the correct answer as it specifically refers to the combined DNA molecule formed in genetic engineering.

Correct Answer: D

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

Correct Answer: B

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

Correct Answer: B

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