Which app has NEET PG PYQs from 2012 to 2025?

MedicoApps provides authentic NEET PG previous year questions from 2012 to 2025 with detailed explanations, clinical coverage, and offline access.

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MedicoApps includes over 10,000 meticulously crafted clinical and image-based questions, each with a detailed explanation covering NEET PG, NeXT PG, INI CET, and FMGE exams.

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Yes, MedicoApps is fully offline. You can study and practice previous year questions without an internet connection.

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Yes, MedicoApps includes clinical and image-based questions with complete explanations and references, covering subjects tested in NEET PG.

Does MedicoApps focus on repeated concepts and high-yield topics?

Yes, MedicoApps follows an 80/20 high-yield preparation approach, emphasising repeated concepts since 60-75% of NEET PG questions come from concepts tested in past exams.

Is there an update frequency for new questions in MedicoApps?

The app is regularly updated to align with the latest NEET PG exam patterns and includes new questions as per evolving trends in medical entrance exams.

Do the questions in MedicoApps come with detailed explanations?

Yes, each question is accompanied by an explanatory note that clarifies the concept behind the answer and references relevant sources.

Which previous year exams are included in MedicoApps?

MedicoApps includes authentic previous year questions from NEET PG, NeXT PG, INI CET, and FMGE exams, spanning from 2012 to 2025.

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Yes, MedicoApps is suitable for both beginners and advanced students. It offers a wide range of questions to support preparation at all stages.

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Yes, MedicoApps offers a no-questions-asked 30-day money-back guarantee on all premium plans.

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A good NEET PG QBank should include PYQs, clinical MCQs, image-based questions, and grand tests. MedicoApps provides all these features along with offline access and explanations in one platform.

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You can practice NEET PG previous year questions on MedicoApps, which includes 10,000+ questions from 2012 to 2025 with detailed explanations and offline support.

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You can reach the MedicoApps customer support team through the app or the official website at medicoapps.org.

ANTIGEN ANTIBODY REACTION AND PRECIPITATION REACTION

Antigen antibody reaction

Are reversible specific non-covalent biochemical reactions
It is a specific chemical interaction between antibodies produced by B cells of the white blood cells and antigens during immune reaction.
Precipitation reactions are based on the interaction of antibodies and antigens.
They are based on two soluble reactants that come together to make one insoluble product, the precipitate
Form basis for
- Humoral immunity or antibody mediated immunity
- Detection of infectious disease causing organism

Ag-Ab reaction occurs in three stages

Primary Stage
- Formation of Ag-Ab complex
- Ag-Ab combined by weaker intermolecular forces
- van der Waals,
- ionic bond
- H₂ binding
Secondary stage
- leads precipitation
- agglutination
- lysis of cells etc.
Tertiary stage (reaction):

Leads to tissue damage

Destruction of Ag or its Neutralization

Types of Antigen-antibody reactions

Types of antigen- antibody reactions in vivo:

Agglutination
Precipitation
Complement fixation
Neutralization
Antibody dependent cell mediated cytotoxicity (ADCC)
Immobilization

Types of antigen antibody reactions used in vitro:

Agglutination
Precipitation
Neutralization
Complement fixation
Fluorescent Fluorescent-antibody technique antibody technique
ELISA- Enzyme-linked immunosorbent assay
Radioimmunoassay
Immunochromatography (ICT)

Precipitation reaction

Sensitive in detection of antigens
As little as 1 g of protein can be detected by precipitation tests.
Precipitation is relatively less sensitive for the detection qf antibodies.

Mechanism of precipitation.

Marrack (1934) proposed the lattice hypothesis
Based on the interaction of antibodies and antigens.
Two soluble reactants that come together to make one insoluble product, the precipitate .
When antigen and antibody exist in optimal proportions formation of lattices (cross-links).

Method

Soluble antigen combines with its antibody in the presence of electrolytes (NaCI)
At a suitable temperature and pH
Antigen antibody complex forms an isoluble precipitate.

The amount of precipitate formed is greatly influenced by the:

Relative proportions of antigens and antibodies
The Ab avidity

Plot in a curve

Three zones are detected ,If
- Varying amounts of Ag are mixed and incubated with Constant volume of antisera

Zone of Ag excess :
- insufficient Ab
- Too small complexes to precipitate
Equivalence zone :
- Large lattice is formed
- Visible precipitates
Zone of Ab excess :
- not enough Ag
- Too small complexes to precipitate.

Types

Ring test
- Simplest type
- e.g. Ascoli’s thermoprecipitin test and streptococcal lancefield grouping.
Slide test
- VDRL test of syphilis
- When the heat inactivated (to destroy complement) serum of patient is reacted with freshly prepared non-treponemal antigen, flocculation reaction (antigen and antibody complex are suspended) occurs.
- The flocculation can be observed by using microscope
Tube test
- Kahn test of syphilis
Immunodiffusion/Counter Current immunoelectrophoresis
- ppt in gel
- e.g. Elek test for toxigenicity in diphtheria (double diffusion).
Electroimmunodiffusion
- e.g. rocket electrophoresis for quantitative estimation of antigen.

Exam Important