Why is it important to feed newborn infants every few hours?

Correct Answer: A

Rationale: Step 1: Newborn infants have limited hepatic capacity to store and synthesize glycogen and glucose. Step 2: This limited capacity results in the plasma glucose concentration not being maintained in a normal range for more than a few hours after feeding. Step 3: Feeding every few hours ensures a constant supply of glucose to maintain plasma glucose levels. Step 4: Thus, it is important to feed newborn infants every few hours to prevent hypoglycemia. Summary: A: Correct - Maintaining plasma glucose levels due to limited hepatic capacity. B: Incorrect - Protein concentration is not the primary concern for feeding frequency. C: Incorrect - Keeping food in the stomach constantly does not improve gastrointestinal function. D: Incorrect - Hypoproteinemic edema is not the primary reason for feeding frequency.

Correct Answer: D

Rationale: Step 1: The trophoblast cells of the blastocyst invade the endometrial lining during implantation. Step 2: The trophoblast cells secrete enzymes to digest the nutrient-rich endometrial cells. Step 3: The digested nutrients are absorbed by the trophoblast cells. Step 4: These nutrients are then utilized by the blastocyst for its growth and development. Step 5: This process ensures that the blastocyst receives the necessary nutrition for the first week after implantation. Summary: A: Incorrect. Endometrial secretions are no longer the source of nutrition after implantation. B: Incorrect. While the blastocyst may contain some stored nutrients, they are not sufficient for the first week post-implantation. C: Incorrect. The placenta is not fully functional until later in pregnancy, so it does not provide nutrition in the first week.

Correct Answer: B

Rationale: The correct answer is B, after ovulation in a female. After ovulation, the ruptured follicle transforms into a corpus luteum, which secretes progesterone to support the uterine lining. Prior to ovulation (choice A) there is a mature follicle, not a corpus luteum. Choice C is incorrect as the corpus luteum is a structure in the female reproductive system, not present in semen. Choice D is incorrect as the corpus luteum persists for about 14 days after ovulation, not just on the day of ovulation.

Correct Answer: C

Rationale: The correct answer is C: Head. The head of the sperm contains the nucleus, which houses the DNA. The nucleus carries the genetic information required for fertilization. The midpiece contains mitochondria for energy production, the flagellum provides motility, and the tail is a part of the flagellum. Therefore, the head is the only part of the sperm that houses the nucleus and DNA, making it the correct answer.

Correct Answer: C

Rationale: The correct answer is C: Secondary oocyte. After meiosis I, the primary oocyte forms a secondary oocyte. The secondary oocyte is the cell that can be fertilized by a sperm to form a zygote. Polar bodies are products of oogenesis that do not participate in fertilization. Oogonium is a primordial germ cell in the ovary that undergoes mitosis to form primary oocytes. Therefore, the secondary oocyte is the only viable option for fertilization among the choices provided.