Which one of the following is a cardio selective β1-blocker:

Correct Answer: B

Rationale: The correct answer is B: Metoprolol. Metoprolol is a cardioselective beta-1 blocker, meaning it primarily blocks beta-1 receptors in the heart, leading to a decrease in heart rate and contractility. This selectivity reduces the risk of bronchoconstriction compared to non-selective beta blockers like Timolol (Choice A), Nadolol (Choice C), and Sotalol (Choice D), which can also block beta-2 receptors in the lungs, potentially causing respiratory issues in patients with asthma or COPD. Therefore, Metoprolol is the best choice for patients with cardiovascular conditions who also have respiratory concerns.

Correct Answer: A

Rationale: The correct answer is A because the cuticle is the waxy layer on the leaf surface, palisade mesophyll is the layer of elongated cells where photosynthesis occurs, and stoma is the opening for gas exchange. Epidermis is the outer layer, not the cuticle. Spongy mesophyll is below palisade mesophyll, not above it. Guard cells surround stomata, not spongy mesophyll.

Correct Answer: B

Rationale: To find the mass of hydrogen chloride that reacts with 5.1g of ammonia, we need to use the stoichiometry of the balanced chemical equation. The balanced equation for the reaction between ammonia (NH3) and hydrogen chloride (HCl) is: NH3 + HCl → NH4Cl From the equation, we can see that 1 mole of NH3 reacts with 1 mole of HCl to form 1 mole of NH4Cl. Therefore, the molar ratio of NH3 to HCl is 1:1. First, we need to convert the given mass of ammonia (5.1g) to moles using the molar mass of ammonia (17g/mol): 5.1g NH3 * (1 mol NH3 / 17g NH3) = 0.3 mol NH3 Since the molar ratio of NH3 to HCl is 1:1, the moles of HCl that react with

Correct Answer: C

Rationale: The correct equation for calculating power is P = ΔE / t. Power is defined as the rate at which work is done or energy is transferred. In this equation, ΔE represents the change in energy and t represents the time taken for that change. Dividing the change in energy by the time gives us the power. This equation aligns with the fundamental definition of power. Choice A (P = ΔE × t) is incorrect because it implies that power is directly proportional to both the change in energy and time, which is not always the case. Choice B (P = W × t) is incorrect because it incorrectly uses work (W) in the equation for power, while power is specifically related to the rate at which work is done, not the work itself. Choice D (P = W / ΔE) is incorrect because it suggests power is inversely proportional to the change in energy, which is not a characteristic of power.

Correct Answer: B

Rationale: The correct answer is B: humoral stimuli. Parathyroid hormone secretion is regulated by the concentration of calcium in the blood, which is an example of humoral stimuli. When blood calcium levels decrease, parathyroid hormone is released to increase calcium levels. Pituitary gland stimuli (A), neural stimuli (C), and hormonal stimuli (D) are not directly involved in the regulation of parathyroid hormone secretion.