Correct Answer: B

Rationale: The correct statement regarding menstruation is that during this time, an unfertilized egg is discharged along with the shedding of the uterine lining. Choice A is incorrect because the endometrium is shed during menstruation. Choice C is incorrect as menstruation does not prevent a female from engaging in sexual activity with her partner. Choice D is incorrect as a fertilized egg does not undergo mitosis during menstruation but rather implants in the uterine lining for further development.

Correct Answer: C

Rationale: Sickle-cell anemia is a genetic disorder caused by inheriting two copies of a recessive gene, one from each parent. The correct answer is C. Choice A is incorrect because sickle-cell anemia is not primarily caused by a chromosomal abnormality. Choice B is incorrect as the condition is not linked to a single segment found only on the Y chromosome. Choice D is unrelated as it mentions a decrease in estrogen levels, which is not a cause of sickle-cell anemia.

Correct Answer: B

Rationale: The correct answer is B: 'FALSE.' Monozygotic (MZ) twins are identical twins, not fraternal. Fraternal twins are dizygotic (DZ). The statement in the question is incorrect as MZ twins are genetically identical, while fraternal twins actually refer to dizygotic twins who develop from two separate fertilized eggs. Therefore, monozygotic twins are not known as fraternal twins, making option B the correct choice. Options A, C, and D are incorrect as they do not accurately describe the relationship between monozygotic and fraternal twins.

Correct Answer: C

Rationale: The endoderm is the correct answer. It is the innermost layer of the embryo that gives rise to organs such as the lungs, digestive system, liver, and pancreas. The neural tube (Choice A) forms the brain and spinal cord, not the lungs or digestive system. Mesoderm (Choice B) develops into structures like muscles, bones, and circulatory system, not the lungs or digestive system. The umbilical cord (Choice D) serves as a connection between the embryo and the placenta, providing nutrients and oxygen, but it is not the layer from which lungs and digestive system develop.

Correct Answer: D

Rationale: Upon admission to the nursery, a healthcare provider should expect the newborn's chest circumference to be slightly smaller than the head circumference. This is a normal finding in newborns due to their physiological development. Bulging fontanels (Choice A) can indicate increased intracranial pressure, which is abnormal. Nasal flaring (Choice B) is a sign of respiratory distress and is also an abnormal finding. While a length from head to heel of 40 cm (15.7 in) (Choice C) falls within the normal range for newborns, it is not a specific expectation upon admission to the nursery. Therefore, the correct expectation for a newborn upon admission is for the chest circumference to be slightly smaller than the head circumference.