Which of the following is an example of an oviparous animal?

Correct Answer: A

Rationale: The correct answer is A: Pigeon. Oviparous animals are those that lay eggs, and pigeons fall under this category. Choice B, Elephant, is incorrect because elephants are viviparous, giving birth to live young. Choice C, Sheep, is also incorrect as sheep are viviparous animals. Choice D, None of the above, is not the correct answer as a pigeon is indeed an example of an oviparous animal.

Correct Answer: B

Rationale: In patients with Polycystic Ovary Syndrome (PCOS), the LH/FSH ratio is most likely to be increased. This hormonal imbalance is a key characteristic of PCOS, where elevated LH levels relative to FSH contribute to the pathophysiology of the condition. Choice A, progesterone/estrogen ratio, is not typically a defining feature of PCOS. Choice C, FSH/LH ratio, is the reverse of what is commonly observed in PCOS. Choice D, glucagon/insulin ratio, is not directly related to the hormonal imbalances seen in PCOS.

Correct Answer: C

Rationale: Estrogen is the hormone responsible for promoting endometrial growth. Estrogen helps thicken the endometrium during the menstrual cycle in preparation for implantation. LH (Choice A) and FSH (Choice B) are involved in regulating the menstrual cycle but do not directly promote endometrial growth. Progesterone (Choice D) is important for maintaining the endometrium after ovulation but is not the primary hormone responsible for promoting its growth.

Correct Answer: B

Rationale: The correct answer is B. The placenta serves as a crucial organ during pregnancy, facilitating the exchange of gases (oxygen and carbon dioxide) and nutrients (such as glucose and amino acids) between the mother and the developing fetus. This exchange is vital for the fetus's growth and development. Choices A, C, and D are incorrect. The placenta does not secrete insulin; insulin is produced by the pancreas. While the placenta provides some immune support to the fetus, its main role is not immunological protection. Additionally, storing fat-soluble vitamins is not a primary function of the placenta.

Correct Answer: A

Rationale: The correct answer is Prolactin. Prolactin is the hormone responsible for regulating the production of milk after childbirth. It stimulates the mammary glands in the breasts to produce milk. Oxytocin, on the other hand, is responsible for the ejection of milk from the breasts. Estrogen and progesterone play roles in the menstrual cycle and pregnancy but are not directly involved in milk production. Therefore, choices B, C, and D are incorrect.