Which of the following is not a barrier method of birth control?

Correct Answer: C

Rationale: The correct answer is C, Sterilization. Sterilization is a permanent form of birth control that involves surgical procedures to prevent pregnancy by blocking the fallopian tubes or vas deferens. Barrier methods physically prevent sperm from reaching the egg, such as vaults, diaphragms, and cervical caps. These devices create a barrier to sperm, unlike sterilization. Therefore, choices A, B, and D are all considered barrier methods of birth control.

Correct Answer: A

Rationale: Hyaluronidase is the correct answer. It is a lytic enzyme released by the sperm to help penetrate the egg's protective layer. Trypsin is a digestive enzyme produced in the pancreas, not released by sperm. Helicase is an enzyme involved in DNA replication, not released by sperm. 'None of the above' is incorrect as hyaluronidase fits the description provided in the question.

Correct Answer: B

Rationale: The correct answer is B: Cord blood stem cells. The umbilical cord contains stem cells that are found in cord blood, known as cord blood stem cells. These stem cells have the potential to develop into various types of cells and are used in medical treatments. Pluripotent stem cells are typically found in embryos and have the ability to develop into any type of cell in the body, not specifically in the umbilical cord. Choice C, blood stem cells, is a vague term that does not specifically refer to the stem cells found in the umbilical cord. Choice D is incorrect as the umbilical cord does contain cord blood stem cells.

Correct Answer: C

Rationale: The correct answer is testosterone. Testosterone is the primary male sex hormone produced in the testes. Progesterone is a female sex hormone primarily produced in the ovaries, not in the testes. Vasopressin is a hormone released by the pituitary gland to regulate water balance in the body, not produced by the testes. Therefore, choices A, B, and D are incorrect.

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.