The term catecholamine best describes drugs that are:

Correct Answer: D

Rationale: The correct answer is D because catecholamines are structurally similar to adrenaline and noradrenaline, sharing a catechol nucleus and amine group. This similarity allows them to exert similar pharmacologic effects such as increasing heart rate and blood pressure. Adrenergic receptor blockers (A) inhibit the action of catecholamines, atropine-like drugs (B) block muscarinic receptors, and neostigmine and physostigmine (C) are cholinesterase inhibitors, not catecholamines.

Correct Answer: C

Rationale: The correct answer is C, X and Z. Ionic compounds are formed when a metal (X) reacts with a nonmetal (Z) by transferring electrons to achieve a stable octet configuration. Metal atoms tend to lose electrons to form positively charged cations, while nonmetal atoms tend to gain electrons to form negatively charged anions. In this case, X (metal) and Z (nonmetal) will react to form an ionic compound through electron transfer. Choices A, B, and D are incorrect because they do not involve a metal-nonmetal combination, which is essential for the formation of an ionic compound.

Correct Answer: C

Rationale: The correct answer is C: 160 m. To calculate distance traveled, we use the formula: distance = speed x time. In this case, the speed of the car is 8 m/s (given in the graph) and the time is 20 s. Therefore, distance = 8 m/s x 20 s = 160 m. Choice A is incorrect as it is too low. Choice B is incorrect as it does not account for the full 20 s. Choice D is incorrect as it is too high based on the given speed and time.

Correct Answer: B

Rationale: The correct answer is B because steroid hormones bind to DNA and form a gene-hormone complex, which then regulates gene expression. This directly influences cellular activities at the genetic level. Choices A, C, and D are incorrect because steroid hormones do not activate cyclic AMP, G proteins, or use calcium ions as second messengers for their cellular actions. Steroid hormones act through genomic mechanisms, not via the signaling pathways associated with choices A, C, and D.

Correct Answer: A

Rationale: The correct answer is A because the binding of a steroid hormone to its receptor triggers a series of events that ultimately lead to the transcription of DNA for the gene that is 'turned on'. This process involves the hormone-receptor complex entering the nucleus, binding to specific DNA sequences, recruiting transcription factors, and initiating gene expression. Choice B is incorrect because steroid hormones do not typically use second messengers for signaling. Choice C is incorrect because while some hormones can activate enzymes indirectly, steroid hormones primarily act through gene transcription. Choice D is incorrect because cAMP is typically associated with signaling pathways involving non-steroid hormones like adrenaline.