▶️ Answer/Explanation
In this process, component $1$ represents the antigen (or weakened pathogen) introduced by the vaccine. This triggers an immune response where the body produces both antibodies (component $2$) and memory cells (component $3$). Antibodies provide immediate defense and can be transferred to others (e.g., via breast milk) to provide passive immunity. Memory cells, however, remain in the body for a long duration to recognize the pathogen if it enters again, thus providing long-term immunity. Since component $3$ is specifically linked to long-term protection, it represents the memory cells.
✅ Answer: (D) $3$ only
✅ Answer: (D) $3$ only
▶️ Answer/Explanation
Cholera is caused by the bacterium Vibrio cholerae, which releases a toxin in the digestive system. This toxin triggers the active secretion of chloride ions ($Cl^-$) from the blood into the small intestine. As the concentration of chloride ions in the intestinal lumen rises, it decreases the water potential of the intestinal contents. Consequently, water moves out of the surrounding tissues and blood into the intestine via osmosis. This massive influx of water results in watery diarrhea, leading to a significant increase in the volume of water leaving the body through the anus.
✅ Answer: (C)
✅ Answer: (C)
▶️ Answer/Explanation
Statement $1$ is correct because passive immunity involves receiving ready-made antibodies, such as those passed through breast milk. Statement $2$ is incorrect because passive immunity is short-term; since the body does not produce the antibodies itself, no memory cells are created. Statement $3$ is correct as active immunity occurs when the immune system is triggered by antigens (via infection or vaccination) to produce its own antibodies and memory cells. Therefore, only statements $1$ and $3$ are accurate.
✅ Answer: (C)