Correct Answer: D

Rationale: The correct answer is D: 4 weeks. Low-risk pregnant patients typically have prenatal visits every 4 weeks until 28 weeks of gestation. This frequency allows for adequate monitoring of the pregnancy without being overly burdensome on the patient. Choices A, B, and C are incorrect as they do not align with the standard prenatal care schedule for low-risk pregnancies. Visits that are too frequent may cause unnecessary anxiety for the patient, while visits that are too infrequent may miss important opportunities for monitoring and intervention.

Correct Answer: D

Rationale: After mitosis, the genetic code is typically preserved and remains identical in the new cells. However, mutations can occur due to radiation or environmental influences, leading to changes in the DNA sequence and potentially altering the genetic code. Therefore, the correct answer is 'mutations.' Choices A, B, and C are incorrect because reductions, expulsions, and conceptions do not accurately describe the changes in the genetic code that can result from external factors. Mutations are the only option that reflects the alteration in the genetic code caused by external influences, making it the correct choice in this context.

Correct Answer: A

Rationale: Chromosomes are rod-shaped structures that carry genetic information in the form of DNA. They are typically seen as elongated structures when visualized under a microscope. Choice B, circular, is incorrect as chromosomes do not have a circular shape; they are linear. Choice C, cone-shaped, is not accurate as chromosomes do not resemble cones in any way. Choice D, octagonal, is also incorrect as chromosomes do not have an octagonal appearance. Therefore, the correct answer is A, rod-shaped, which accurately describes the shape of chromosomes.

Correct Answer: B

Rationale: The correct answer is B. Cystic fibrosis is a genetic disorder that causes the body to produce thick, sticky mucus. This mucus can clog the airways in the lungs and obstruct the pancreas, leading to severe respiratory and digestive problems. Choice A is incorrect because uncontrollable muscle movements and personality changes are not typical symptoms of cystic fibrosis. Choice C is incorrect because cystic fibrosis does not directly cause red blood cells to clump together and obstruct small blood vessels. Choice D is incorrect because cystic fibrosis primarily affects the respiratory and digestive systems, not the central nervous system.

Correct Answer: B

Rationale: The correct answer is B: Performing a newborn's initial bath. Gloves should be worn during this procedure to protect against exposure to body fluids, such as amniotic fluid or blood. Assisting a mother with breastfeeding (Choice A) does not typically require gloves unless there are specific reasons for infection control. Administering vaccines (Choice C) and performing umbilical cord care (Choice D) are procedures that may require hand hygiene but not necessarily gloves, unless there is active bleeding or potential exposure to body fluids. The initial bath involves direct contact with body fluids, making it crucial to wear gloves for protection.