Acquired immunity is the defence your body BUILDS after it meets a pathogen. It is not present at birth. It has two main features: it is pathogen-specific (it targets one specific germ) and it has memory (it remembers a germ so the next attack is faster and stronger). Memory hook: acquired = "A" for After exposure, and it is Specific + has Memory (S + M).
Acquired immunity remembers a pathogen. The first meeting gives a slow primary response; the second meeting with the same pathogen gives a fast, strong secondary (anamnestic) response because of memory.
Your doubts, answered
Is acquired immunity present at the time of birth?
No. This is the most common trap in NEET. Acquired immunity is NOT present at birth. It develops during your life, only after your body is exposed to a pathogen (a germ) or a vaccine. The immunity present at birth is INNATE immunity, not acquired. If a NEET option says 'acquired immunity is present at the time of birth', that statement is wrong.
What are the two main features of acquired immunity?
Acquired immunity has exactly two key features you must remember for NEET: (1) Specificity: it is pathogen-specific, meaning it makes a defence aimed at one particular germ. (2) Memory: it remembers a germ it met before, so the second time it responds much faster and stronger.
What is the difference between primary and secondary response?
When your body meets a pathogen for the FIRST time, it makes a slow, low-intensity reply called the primary response. When the SAME pathogen comes again, the body makes a fast, strong reply called the secondary response (also called the anamnestic response). The strong secondary response happens because of memory of the first encounter.
Is acquired immunity specific or non-specific?
Acquired immunity is SPECIFIC (pathogen-specific). It attacks one particular germ that it has learned to recognise. Innate immunity is the non-specific one that acts the same way against all germs. NEET often swaps these two words to trick you, so link acquired = specific, innate = non-specific.
Why is acquired immunity also called adaptive immunity?
It is called adaptive because it adapts, or changes, based on the germs your body meets. It builds a custom, specific defence for each new pathogen and keeps a memory of it. Because it is acquired (built) during life and adapts to each germ, the names 'acquired immunity' and 'adaptive immunity' mean the same thing.
⚠️ The NEET trap ✗ Acquired immunity is a non-specific type of defence present at the time of birth. ✓ Acquired immunity is pathogen-specific and is characterised by memory; it develops AFTER exposure and is NOT present at birth. The non-specific defence present at birth is innate immunity. 🧠 If the words 'non-specific' or 'present at birth' appear next to 'acquired immunity', the statement is WRONG. Those two words belong to INNATE immunity. This exact swap was the answer in NEET 2022.
Real NEET questions
2022
Select the incorrect statement with respect to acquired immunity:
A · Primary response is produced when our body encounters a pathogen for the first time.
B · Anamnestic response is elicited on subsequent encounters with the same pathogen.
C · Anamnestic response is due to memory of first encounter.
D · Acquired immunity is non-specific type of defence present at the time of birth. ✓
Solution: Option D is INCORRECT, so it is the answer. Acquired immunity is pathogen-SPECIFIC and has MEMORY; it develops after exposure. It is INNATE immunity that is non-specific and present at birth. Options A, B and C correctly describe the primary response (first encounter) and the anamnestic/secondary response (due to memory).
2016
In higher vertebrates, the immune system can distinguish self-cells and non-self. If this property is lost due to genetic abnormality and it attacks self-cells, then it leads to:
A · Allergic response
B · Graft rejection
C · Auto-immune disease ✓
D · Active immunity
Solution: Memory-based acquired immunity depends on the ability to tell self-cells from foreign (non-self) cells. If this ability is lost due to a genetic reason and the body attacks its own cells, it causes an auto-immune disease, for example rheumatoid arthritis.
Solved Human Health and Diseases NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is the defence your body builds during your life after it meets a germ or gets a vaccine. It is specific to that germ and remembers it for next time.
What are the two features of acquired immunity for NEET?
Specificity (it is pathogen-specific) and memory (it remembers a germ and reacts faster and stronger on the next attack).
Is acquired immunity the same as innate immunity?
No. Innate immunity is non-specific and present at birth. Acquired immunity is specific, has memory, and develops after exposure. Do not swap these in NEET.
What is the anamnestic response?
It is another name for the secondary response, the fast and strong reply the body gives when the same pathogen attacks again. It happens because of memory.
Why does the second infection cause less illness?
Because of memory cells from the first exposure, the secondary response is quick and strong. It clears the germ before it can make you very sick.
