Which of the following is an example of passive immunity?
A.
The body’s response to a vaccine
B.
The transfer of antibodies from a mother to her baby during breastfeeding
C.
The activation of T cells in response to an infection
D.
The production of memory cells after exposure to a pathogen
The Correct answer and Explanation is:
The correct answer is B. The transfer of antibodies from a mother to her baby during breastfeeding.
Explanation:
Immunity refers to the body’s ability to defend against pathogens and diseases. There are two primary types of immunity: active and passive immunity. Understanding the distinction between these two types is crucial for comprehending how the body fights off infections.
Active immunity occurs when the body’s immune system is directly involved in producing a response to a pathogen. This can happen naturally, as when a person contracts a disease and the immune system responds, or artificially, through vaccination. In active immunity, the body is exposed to an antigen (a substance that the immune system recognizes as foreign) and responds by producing antibodies and memory cells. These memory cells “remember” the pathogen, providing long-term protection against future infections.
Examples of active immunity include:
- The body’s response to a vaccine (Option A): Vaccines introduce a harmless part of the pathogen (or a weakened or dead version) into the body, prompting the immune system to produce antibodies and memory cells without causing the disease.
- The production of memory cells after exposure to a pathogen (Option D): After encountering a pathogen, the immune system creates memory cells that provide long-lasting immunity.
Passive immunity, on the other hand, involves the transfer of antibodies from one individual to another, rather than the body producing its own immune response. This type of immunity provides immediate, but temporary, protection. Since the body does not produce memory cells in passive immunity, the protection lasts only as long as the antibodies remain in the bloodstream.
The most common examples of passive immunity include:
- Transfer of antibodies from a mother to her baby during breastfeeding (Option B): During breastfeeding, a mother passes antibodies, particularly Immunoglobulin A (IgA), to her baby. These antibodies help protect the baby from infections in the early months of life when the baby’s immune system is still developing.
- Receiving an injection of antibodies (e.g., antivenom): In cases where immediate protection is needed, such as after a snakebite, antivenom (which contains antibodies) is administered to neutralize the toxin.
Activation of T cells in response to an infection (Option C) is another example of active immunity, where the body’s immune system is actively responding to a pathogen.
In summary, Option B is the correct example of passive immunity, where antibodies are transferred from the mother to the baby during breastfeeding, providing the baby with immediate, short-term protection against pathogens.