An individual who has had chicken pox rarely gets the disease again. This situation is an example of

Correct Answer: C

Rationale: Step-by-step rationale: 1. Active immunity is when the body produces its antibodies after being exposed to a specific pathogen. 2. When someone has chicken pox, their immune system creates memory cells that recognize the virus. 3. If exposed to the virus again, the memory cells quickly respond, preventing re-infection. 4. This demonstrates active immunity as the individual's immune system actively defends against the pathogen. Summary: A: Biological control does not apply as it refers to natural predators controlling pest populations. B: Negative feedback is a regulatory mechanism in the body, not related to immunity. D: Passive immunity involves receiving pre-formed antibodies, not the body's own immune response like in the case of chicken pox.

Correct Answer: B

Rationale: The correct answer is B because bringing the sexual partner in for treatment is a key aspect of preventing the spread of genital warts. By ensuring that the partner is screened and treated, it helps to prevent reinfection and further transmission. Choice A is incorrect as resuming sexual activity before the lesions are healed can lead to the spread of infection. Choice C is incorrect because condom use should continue even after treatment to prevent the transmission of STIs. Choice D is incorrect as proper hygiene, including washing the affected area, is important in managing genital warts and preventing complications.

Correct Answer: B

Rationale: The correct answer is B: Rheumatoid factor. An increase in rheumatoid factor can indicate arthritis, specifically rheumatoid arthritis, as it is an autoantibody that targets healthy tissue in the joints. This is a key diagnostic marker for rheumatoid arthritis. A: Direct Coomb's test is used to detect antibodies on the surface of red blood cells, not specific to arthritis. C: Blood urea nitrogen (BUN) is a measure of kidney function and not typically associated with arthritis. D: Platelet count is unrelated to arthritis and is more indicative of clotting disorders or other conditions.

Correct Answer: C

Rationale: The correct answer is C: Acquired immunity develops after birth. This statement is correct because acquired immunity refers to the immunity that develops after exposure to antigens, such as through infection or vaccination. It involves the immune system recognizing and remembering specific pathogens to provide protection in the future. This shows the mother understands the difference between natural (innate) immunity, which is present at birth, and acquired immunity, which develops over time. Incorrect choices: A: Natural immunity develops when my baby receives immunizations - This is incorrect as immunizations are a form of acquired immunity. B: Natural immunity is only present before the baby is born - This is incorrect as natural immunity is present at birth and acquired immunity develops after birth. D: Acquired immunity develops only after exposure to an illness - This is incorrect as acquired immunity can also develop through vaccinations, not just exposure to illnesses.

Correct Answer: D

Rationale: Iron is primarily absorbed in the duodenum, the first part of the small intestine. The duodenum is where iron is released from food and converted into a form that can be absorbed by the body. The acidic environment in the stomach helps to break down iron-containing compounds, but actual absorption occurs in the duodenum. The ileum and jejunum are also parts of the small intestine, but they are not the primary sites of iron absorption. The stomach is involved in initial digestion but not in the absorption of iron. Therefore, the correct answer is D, the duodenum.