Question

Given below are two statements: one is labelled as Assertion (A) and the other as Reason (R). Assertion (A): When readymade antibodies are directly given to protect the body against foreign agents, it is called passive immunity. Reason (R): The yellowish fluid colostrum secreted by mother contains antibodies (IgA) to protect the infant. Choose the correct answer from the options given below:

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Types of immunity: \[ \text{Active Immunity} = \text{Body produces its own antibodies} \] \[ \text{Passive Immunity} = \text{Ready-made antibodies are received} \] Examples of passive immunity: \[ \text{Colostrum (IgA)} \] \[ \text{Maternal antibodies through placenta} \] \[ \text{Antiserum injections} \]

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Immunity is the body's ability to defend itself against pathogens. It can be broadly classified into Active Immunity and Passive Immunity: - Active Immunity: Developed when the host's own body cells produce antibodies in response to an infection or vaccine. It is slow but long-lasting. - Passive Immunity: Acquired when pre-synthesized, readymade antibodies are introduced directly into the body from an external source. It provides immediate protection but does not create long-term immunological memory.
Step 2: Detailed Explanation:
Let's evaluate each statement independently: 1. Evaluate Assertion (A): "When readymade antibodies are directly given to protect the body against foreign agents, it is called passive immunity." - This statement perfectly defines passive immunity. Examples include injecting anti-tetanus serum (ATS) or anti-venom when someone is bitten by a snake. Thus, Assertion (A) is True. 2. Evaluate Reason (R): "The yellowish fluid colostrum secreted by mother contains antibodies (IgA) to protect the infant." - Colostrum is the initial milk produced by a mother during the first few days after giving birth. It is highly concentrated with Immunoglobulin A ($\text{IgA}$) antibodies that pass directly to the newborn baby to shield its fragile digestive and respiratory tracts. Thus, Reason (R) is also factually True. 3. Evaluate the Logical Connection: - Now, we check if R explains A. Let's join them using the word because: "When readymade antibodies are given directly to protect the body, it is called passive immunity because colostrum contains IgA antibodies." - This sentence does not flow logically. While colostrum is an excellent example of natural passive immunity, its presence is not the biological reason why the entire concept is defined as passive immunity. The definition of passive immunity (Assertion) rests on the fact that the host's body is passive and receives ready-to-fight molecules instead of producing them. Therefore, both statements are independently true, but R is not the correct explanation of A. This matches option (B).
Step 3: Final Answer:
Both A and R are true but R is not the correct explanation of A.