Propranolol can produce the following EXCEPT:

Correct Answer: A

Rationale: The correct answer is A: Stimulation of beta adrenergic receptors. Propranolol is a beta-blocker that works by blocking beta adrenergic receptors, not stimulating them. Blocking these receptors leads to decreased heart rate, reduced cardiac contractility, and lowered blood pressure. Choices B, C, and D are incorrect because propranolol actually blocks beta adrenergic receptors, depresses cardiac contractility, and decreases blood pressure, respectively.

Correct Answer: D

Rationale: The correct answer is D: "Inhibits breakdown of acetylcholine, thereby improving activation of skeletal muscle by acetylcholine." Rationale: 1. Pyridostigmine is an acetylcholinesterase inhibitor, which means it blocks the breakdown of acetylcholine. 2. In myasthenia gravis, there is a decrease in acetylcholine receptor sites, leading to muscle weakness. 3. By inhibiting the breakdown of acetylcholine, pyridostigmine increases the availability of acetylcholine at the neuromuscular junction, improving muscle activation. 4. This mechanism helps alleviate muscle weakness in myasthenia gravis patients. Summary: A: Incorrect. Pyridostigmine does not block muscarinic receptors or change the preference of acetylcholine stimulation. B: Incorrect. Pyridostigmine does not inhibit reuptake of acetylcholine; it acts by inhibiting its breakdown

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.