Twins resulting from the fertilization of separate ova by separate sperm cell are called:

Correct Answer: C

Rationale: The correct answer is C: Fraternal twins. Fraternal twins result from the fertilization of separate ova by separate sperm cells, leading to siblings who share 50% of their genetic material. This is different from identical twins (choice D), which result from the fertilization of a single egg by a single sperm cell, leading to siblings who share 100% of their genetic material. Choices A and B are incorrect as they do not accurately describe the process of fraternal twinning. Paternal twins (choice A) and maternal twins (choice B) are not commonly used terms in genetics to describe types of twinning.

Correct Answer: D

Rationale: The correct answer is D: Vomer. The vomer is a thin, single flat bone that forms the lower portion of the nasal septum. It articulates with the sphenoid, ethmoid, and maxillary bones. The lacrimal bones (A) are small bones forming part of the eye socket. Nasal bones (B) are two small bones that form the bridge of the nose. The inferior nasal concha (C) is a separate bone located in the nasal cavity, not part of the nasal septum. Therefore, the vomer is the correct answer as it specifically fits the description given in the question.

Correct Answer: D

Rationale: The correct answer is D: Reduction. In medical terminology, reduction refers to the process of restoring a dislocated or fractured bone to its normal position. In this context, the patient was likely taken to the operating room for a reduction procedure to realign the affected bone. A: Open - Incorrect because it does not specify the specific procedure being performed. B: Open deduction - Incorrect because "deduction" is not a term commonly used in medical procedures and does not make sense in this context. C: Deduction - Incorrect for the same reasons as B, as deduction is not a relevant medical term in this scenario.

Correct Answer: A

Rationale: The correct answer is A: Patella. The patella, also known as the kneecap, is a flat bone located in the front of the knee joint. It serves to protect the knee joint and improve the leverage of the quadriceps muscles during movement. The other choices, such as the shoulder blade (B), hand bone (C), and thigh bone (D), are not flat bones. The shoulder blade is a scapula, a flat and triangular bone. The hand bone refers to the metacarpal and phalanges, which are long bones. The thigh bone is the femur, a long bone in the upper leg. The patella's unique flat shape and location make it the correct choice.

Correct Answer: A

Rationale: The correct answer is A: Syncytiotrophoblast. This layer of the placenta secretes human chorionic gonadotropin (HCG), a hormone crucial for maintaining pregnancy by supporting the corpus luteum to produce progesterone. Syncytiotrophoblast is a multinucleated layer formed from the fusion of cytotrophoblast cells and is responsible for hormone secretion. B: Cytotrophoblast is the inner layer of the trophoblast but does not secrete HCG. C: Endometrium is the lining of the uterus and is not part of the placenta. D: Chorion is a membrane that contributes to the formation of the placenta but does not secrete HCG.