Organophosphate insecticides and nerve gases exert their lethal effects by:

Correct Answer: D

Rationale: The correct answer is D because organophosphate insecticides and nerve gases inhibit acetylcholine metabolism by irreversibly binding to acetylcholinesterase enzyme, leading to accumulation of acetylcholine at synapses. This results in overstimulation of cholinergic receptors, causing symptoms of cholinergic toxicity. Choice A is incorrect because alpha and beta-adrenergic receptors are not the targets of organophosphates. Choice B is incorrect because organophosphates do not block all muscarinic receptors. Choice C is incorrect because organophosphates do not specifically target nicotinic receptors in the brain.

Correct Answer: D

Rationale: The correct answer is D because lead is the product at the cathode (negative electrode) during electrolysis, while bromine is the product at the anode (positive electrode). Lead is reduced at the cathode to form lead metal, and bromine is oxidized at the anode to form bromine gas. This is in line with the general rule that cations are attracted to the cathode and are reduced, while anions are attracted to the anode and are oxidized. Choice A is incorrect as bromide ions are reduced at the cathode, not lead ions. Choice B is incorrect because bromine is produced at the anode, not lead. Choice C is incorrect because lead ions are reduced at the cathode, not bromide ions.

Correct Answer: D

Rationale: The correct answer is D: solidification. Solidification is the process in which a substance changes from a liquid state to a solid state by losing heat energy. In this process, the particles slow down and come closer together, forming a solid structure. Explanation for why the other choices are incorrect: A: Condensation is the change of state from gas to liquid, not from liquid to solid. B: Evaporation is the change of state from liquid to gas, not from liquid to solid. C: Melting is the change of state from solid to liquid, not from liquid to solid. In summary, the process described in the question, changing from a liquid state to a solid state, is known as solidification, making it the correct answer.

Correct Answer: D

Rationale: The correct answer is D: high blood glucose concentration. Insulin is released by the pancreas in response to increased blood glucose levels. High blood glucose signals the body to lower it by facilitating the uptake of glucose into cells. Low blood amino acid, fatty acid, or glucose concentrations would not stimulate insulin release as they do not directly regulate blood sugar levels.

Correct Answer: A

Rationale: Rationale: POMC is processed into various peptide hormones, including adrenocorticotropic hormone (ACTH). ACTH is produced by the pituitary gland and stimulates the adrenal glands to release cortisol. This is why option A is correct. Growth hormone, thyroxin, and insulin are not derived from POMC, making options B, C, and D incorrect.