The cell produced by fertilization is called

Correct Answer: D

Rationale: The correct answer is D: zygote. After fertilization, the sperm and egg fuse to form a zygote, which is the first cell of a new organism with a full set of chromosomes. A. Gamete refers to the sex cells (sperm and egg) before fusion. B. Embryo is the developmental stage after the zygote undergoes multiple cell divisions. C. Fetus is the term used for the developing organism after the embryo stage. Therefore, the correct term for the cell produced by fertilization is zygote as it represents the initial stage of the new organism's development.

Correct Answer: A

Rationale: Step-by-step rationale for why A (oxytocin) is the correct answer: 1. Oxytocin is known as the "love hormone" and is primarily responsible for stimulating uterine contractions during labor. 2. It is produced by the hypothalamus and released by the pituitary gland. 3. Oxytocin plays a crucial role in childbirth, breastfeeding, and bonding between mother and child. Summary: B: Estrogen is a female sex hormone that regulates the menstrual cycle and development of female secondary sexual characteristics. C: Granular cell carcinoma is a type of cancer that does not have any relation to uterine contractions. D: Progesterone is another female sex hormone that helps maintain pregnancy and prepare the body for childbirth, but it does not directly stimulate uterine contractions like oxytocin does.

Correct Answer: B

Rationale: The correct answer is B: Phenobarbital. Phenobarbital was the first agent introduced for the treatment of epilepsy in the early 1900s. It was discovered to have anticonvulsant properties and became a mainstay in epilepsy treatment. Phenytoin (A), Carbamazepine (C), and Valproic acid (D) were introduced later than Phenobarbital and are not the first agents used for epilepsy treatment. Therefore, the correct answer is Phenobarbital as it was the first agent specifically developed and used for epilepsy treatment.

Correct Answer: B

Rationale: The correct answer is B: D2. Atypical antipsychotics primarily target dopamine D2 receptors, reducing dopamine activity. This helps alleviate symptoms of psychosis with fewer extrapyramidal side effects compared to typical antipsychotics that target D1 receptors. Choice A: D1 receptors are not the primary target for atypical antipsychotics. Choice C: D3 receptors are not the main target, although some atypical antipsychotics may have activity at D3 receptors. Choice D: D4 receptors are not the main target for atypical antipsychotics.

Correct Answer: A

Rationale: The correct answer is A because buprenorphine is a partial agonist at the Mu receptor. This means it can activate the receptor but with less efficacy compared to a full agonist, resulting in a ceiling effect and lower risk of respiratory depression. Choice B is incorrect because buprenorphine is not a full agonist at the Mu receptor. Choices C and D are incorrect as buprenorphine primarily acts on the Mu receptor, not the K receptor.