In the pancreas, which are the cells that secrete insulin?

Correct Answer: B

Rationale: The correct answer is B: Beta cells. Beta cells in the pancreas are responsible for secreting insulin. Insulin helps regulate blood sugar levels. Alpha cells (A) secrete glucagon, Delta cells (C) secrete somatostatin, both involved in glucose metabolism, but not insulin secretion. Choice D is incorrect as the pancreas does contain cells that secrete insulin.

Correct Answer: B

Rationale: The correct answer is B: cellular mutations occur. Hormones typically act through binding to specific receptors on target cells to initiate a signaling cascade. This process does not involve inducing mutations in the cell's DNA. Plasma membrane permeability changes, enzyme activation/inactivation, and stimulation of mitosis are all well-established mechanisms of hormone action. Therefore, B is the correct answer as it does not align with the usual mechanisms by which hormones exert their effects.

Correct Answer: B

Rationale: The correct answer is B because the endocrine system releases hormones into the bloodstream, allowing them to reach all parts of the body simultaneously and produce widespread responses. In contrast, the nervous system sends signals through nerve cells, which can only target a small number of specific cells. This difference in distribution and reach of signals is a key distinction between the endocrine and nervous systems. Choice A is incorrect because a single hormone can indeed target multiple responses in different parts of the body, similar to how a nerve signal can affect multiple cells along its path. Choice C is incorrect as nerve cells and the endocrine system can interact and influence each other's functions, such as in the case of stress response involving both systems. Choice D is incorrect because endocrine hormones can have broad effects on various organs and tissues, not limited to a small number of precise responses.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Dopamine and homovanillic acid are neurotransmitters. 2. Neuroblastoma is a type of cancer that originates in neuroblasts, which are immature nerve cells. 3. Neuroblastoma can produce neurotransmitters like dopamine and homovanillic acid. 4. Therefore, dopamine and homovanillic acid are secreted in neuroblastoma. Summary: - Choice A is correct as neuroblastoma can secrete dopamine and homovanillic acid. - Choices B and C are incorrect as they are unrelated to the secretion of these neurotransmitters.

Correct Answer: C

Rationale: The correct answer is C, glucagon and epinephrine. Glucagon stimulates the liver to release glucose into the bloodstream, increasing blood sugar levels. Epinephrine, also known as adrenaline, has a similar effect by promoting the breakdown of glycogen into glucose. Insulin (choice A) decreases blood sugar by promoting glucose uptake into cells. Growth hormone (choice B) mainly affects growth and metabolism but doesn't directly increase blood sugar. Antidiuretic hormone (choice D) regulates water balance and has no direct effect on blood sugar levels.