ATI RN
Human Reproductive System pdf NCERT Questions
Question 1 of 5
RU486 causes abortion if it is administered before or soon after implantation. What is the specific effect of RU486?
Correct Answer: B
Rationale: The correct answer is B, as RU486 blocks progesterone receptors, preventing progesterone from exerting its effects. Progesterone is crucial for maintaining the uterine lining to support a pregnancy. By blocking progesterone receptors, RU486 causes the uterine lining to break down, leading to the expulsion of the embryo and ultimately causing abortion. Choice A is incorrect because RU486 does not bind to luteinizing hormone receptors or stimulate progesterone secretion. Choice C is incorrect because RU486 does not block the secretion of follicle-stimulating hormone; its mechanism of action is specific to progesterone receptors. Choice D is incorrect because RU486 does not block the effects of oxytocin receptors in the uterine muscle; its primary action is on progesterone receptors.
Question 2 of 5
A man who has been exposed to high levels of gamma radiation is sterile due to destruction of the germinal epithelium of the seminiferous tubules, although he has normal levels of testosterone. Which of the following would be found in this patient?
Correct Answer: A
Rationale: Step 1: High levels of gamma radiation cause destruction of germinal epithelium, leading to infertility. Step 2: Normal testosterone levels indicate intact Leydig cells, responsible for testosterone production. Step 3: Normal secretory pattern of gonadotropin-releasing hormone (GnRH) is expected as it regulates pituitary hormone secretion. Step 4: Inhibin is produced by Sertoli cells (part of germinal epithelium) and would be decreased due to destruction. Step 5: Follicle-stimulating hormone (FSH) levels would be elevated, not suppressed, due to lack of inhibin feedback. Step 6: Leydig cells are intact, so Leydig cells are not absent in this scenario.
Question 3 of 5
At what point in life does a female begin her monthly ovarian cycle?
Correct Answer: B
Rationale: The correct answer is B: At puberty. The monthly ovarian cycle, also known as the menstrual cycle, begins at puberty when a female's body matures and starts ovulating. This is typically around the age of 11-14. At birth (A), females already have all their eggs but do not start ovulating until puberty. Middle age (C) refers to the period around 40-65, which is not when the cycle begins. Menopause (D) is the cessation of the menstrual cycle, marking the end of reproductive years, typically around the age of 45-55.
Question 4 of 5
What excess cellular component do spermatids shed to become sperm during spermiogenesis?
Correct Answer: B
Rationale: During spermiogenesis, spermatids shed excess cytoplasm to become mature sperm. This process helps streamline the sperm structure for efficient motility and fertilization. DNA (choice A) is essential for sperm function and remains within the sperm. The flagellum (choice C) is actually a necessary structure for sperm motility. Mitochondria (choice D) play a crucial role in providing energy for sperm movement. Shedding excess cytoplasm ensures that the mature sperm is streamlined and optimized for its specific functions.
Question 5 of 5
Which of the following is responsible for secondary sex characteristics in females?
Correct Answer: A
Rationale: Estrogens are responsible for secondary sex characteristics in females as they promote breast development, regulate the menstrual cycle, and contribute to the distribution of body fat. Progesterone mainly prepares the uterus for pregnancy. Follicle-stimulating hormone (FSH) plays a role in the development of ovarian follicles and the maturation of eggs but does not directly influence female secondary sex characteristics.