Peptide hormones function by binding to receptor proteins within the ________. Once the hormone binds to a receptor, it activates ______.

Correct Answer: C

Rationale: The correct answer is C because peptide hormones typically bind to receptor proteins on the plasma membrane. This is because peptide hormones are not able to pass through the cell membrane due to their size and polarity. Once the hormone binds to the receptor on the plasma membrane, it activates a second messenger system within the cell, leading to various cellular responses. Choice A is incorrect because peptide hormones do not bind directly to intracellular components like second messengers inside the cell. Choice B is incorrect because peptide hormones do not directly activate particular genes within the cell. Choice D is incorrect because peptide hormones do not bind directly to genes on the plasma membrane.

Correct Answer: A

Rationale: The correct answer is A: thyroid hormone. The thyroid hormone plays a crucial role in regulating metabolism by increasing the body's metabolic rate. It accomplishes this by stimulating the production of proteins that control the rate at which cells use energy. Calcitonin (B) is involved in regulating calcium levels in the blood, not metabolic rate. Aldosterone (C) is a hormone that regulates electrolyte balance and blood pressure. Parathyroid hormone (D) regulates calcium and phosphorus levels in the blood, not metabolic rate. Thus, the correct choice is thyroid hormone as it directly affects metabolic rate.

Correct Answer: A

Rationale: The correct answer is A: atrial natriuretic hormone (ANH). ANH opposes the actions of aldosterone by promoting salt and water excretion, thus reducing blood volume and blood pressure. ANH is released in response to high blood pressure or high blood volume. B: antidiuretic hormone (ADH) is not the antagonistic hormone to aldosterone; it acts on the kidneys to regulate water balance. C: cortisol is a stress hormone and is not directly involved in regulating sodium and water balance. D: glucagon is a hormone that increases blood sugar levels and is not related to the regulation of aldosterone.

Correct Answer: B

Rationale: Leptin is the correct answer because it is a hormone produced by adipose tissue that signals satiety to the brain, helping regulate energy balance and food intake. Melatonin is a hormone that regulates sleep-wake cycles, not hunger. Thymosins are involved in immune function. Glucagon is a hormone that increases blood sugar levels, not related to satiety.

Correct Answer: C

Rationale: Step-by-step rationale for why choice C (Insulin) is correct: 1. A banana split is high in carbohydrates and sugar. 2. Consuming carbohydrates and sugar triggers an increase in blood glucose levels. 3. Insulin is released by the pancreas in response to high blood glucose levels to facilitate the uptake of glucose into cells for energy. 4. Therefore, after consuming a banana split, insulin levels in the body are expected to increase to regulate blood glucose levels. Summary of why other choices are incorrect: - A: Prolactin is a hormone involved in lactation and is not directly related to consuming a banana split. - B: Glucagon is released in response to low blood glucose levels to increase blood sugar, opposite of what is expected after consuming a banana split. - D: Thyroid hormone regulates metabolism and is not directly influenced by consuming a banana split.