Antigens and Antibody

Question 1

What is an antigen?
a) A substance that binds to an antibody
b) A substance that always induces an immune response
c) A type of antibody
d) A T-cell receptor

Answer 1

Answer: a) A substance that binds to an antibody

Question 2

Which of the following is always an immunogen?
a) All antigens
b) All proteins
c) All immunogens
d) Only blood antigens

Answer 2

Answer: c) All immunogens

Question 3

What is the main function of histocompatibility antigens (HLA)?
a) Cause allergic reactions
b) Identify self-cells
c) Destroy pathogens
d) Activate neutrophils

Answer 3

Answer: b) Identify self-cells

Question 4

Which blood type has no antigens?
a) A
b) B
c) AB
d) O

Answer 4

Answer: d) O

Question 5

Which blood type is the universal recipient?
a) A
b) B
c) AB
d) O

Answer 5

Answer: c) AB

Question 6

Which factor does NOT affect antigen influence?
a) Age
b) Dose
c) Route of inoculation
d) Blood pressure

Answer 6

Answer: d) Blood pressure

Question 7

Which route is NOT a mode of antigen transmission?
a) Oral transfusion
b) Organ transplant
c) Injection
d) Skin contact

Answer 7

Answer: d) Skin contact

Question 8

Which factor increases immunogenicity?
a) Low molecular weight
b) High complexity
c) Poor degradability
d) Self-recognition

Answer 8

Answer: b) High complexity

Question 9

Which of the following is the strongest immunogen?
a) Carbohydrates
b) Proteins
c) Lipids
d) Nucleic acids

Answer 9

Answer: b) Proteins

Question 10

What is the minimum molecular weight for immunogenicity?
a) 1,000 daltons
b) 10,000 daltons
c) 50,000 daltons
d) 100,000 daltons

Answer 10

Answer: b) 10,000 daltons

Question 11

Which term refers to self-antigens recognized as foreign?
a) Autoantigens
b) Alloantigens
c) Heteroantigens
d) Immunogens

Answer 11

Answer: a) Autoantigens

Question 12

Which antigen is from a different species?
a) Autoantigen
b) Alloantigen
c) Heteroantigen
d) Isoantigen

Answer 12

Answer: c) Heteroantigen

Question 13

What is the role of haptens?
a) Trigger antibody formation alone
b) Require a carrier for immunogenicity
c) Destroy pathogens
d) Act as antibodies

Answer 13

Answer: b) Require a carrier for immunogenicity

Question 14

Which of the following is an adjuvant function?
a) Suppress the immune response
b) Enhance immunogenicity
c) Prevent antibody formation
d) Block antigen presentation

Answer 14

Answer: b) Enhance immunogenicity

Question 15

Which is the most widely used adjuvant in humans?
a) Freund’s adjuvant
b) BCG
c) Alum precipitate
d) Squalene

Answer 15

Answer: c) Alum precipitate

Question 16

Which immunoglobulin is the most abundant in serum?
a) IgA
b) IgG
c) IgM
d) IgE

Answer 16

Answer: b) IgG

Question 17

Which immunoglobulin is the first produced during infection?
a) IgA
b) IgG
c) IgM
d) IgE

Answer 17

Answer: c) IgM

Question 18

Which immunoglobulin is primarily found in secretions?
a) IgA
b) IgG
c) IgM
d) IgE

Answer 18

Answer: a) IgA

Question 19

Which immunoglobulin is associated with allergies?
a) IgG
b) IgA
c) IgM
d) IgE

Answer 19

Answer: d) IgE

Question 20

Which antibody can cross the placenta?
a) IgA
b) IgG
c) IgM
d) IgE

Answer 20

Answer: b) IgG

Question 21

Which immunoglobulin has a pentameric structure?
a) IgA
b) IgG
c) IgM
d) IgE

Answer 21

Answer: c) IgM

Question 22

Which immunoglobulin has no known function in the immune response?
a) IgG
b) IgA
c) IgD
d) IgE

Answer 22

Answer: c) IgD

Question 23

Which immunoglobulin has subclasses?
a) IgD
b) IgG
c) IgE
d) None

Answer 23

Answer: b) IgG

Question 24

Which antibody has a dimeric form in secretions?
a) IgA
b) IgG
c) IgM
d) IgE

Answer 24

Answer: a) IgA

Question 25

Which immunoglobulin binds to mast cells and basophils? a) IgA b) IgG c) IgM d) IgE

Answer 25

Answer: d) IgE

Question 26

Which immunoglobulin is heat-labile at 56°C? a) IgA b) IgG c) IgM d) IgE

Answer 26

Answer: d) IgE

Question 27

What is the basic structural unit of an antibody? a) Dimer b) Monomer c) Pentamer d) Tetramer

Answer 27

Answer: b) Monomer

Question 28

Which antibody region determines antigen specificity? a) Fab b) Fc c) Hinge d) Constant

Answer 28

Answer: a) Fab

Question 29

Which enzyme cleaves antibodies into two Fab and one Fc fragment? a) Trypsin b) Pepsin c) Papain d) Lysozyme

Answer 29

Answer: c) Papain

Question 30

Which Ig structure contains the variable region? a) Fab b) Fc c) Hinge d) Heavy chain only

Answer 30

Answer: a) Fab

Question 31

Which immunoglobulin is most effective at complement fixation? a) IgA b) IgG c) IgM d) IgE

Answer 31

Answer: c) IgM

Question 32

Which bonds hold antibody chains together? a) Hydrogen b) Disulfide c) Ionic d) Peptide

Answer 32

Answer: b) Disulfide

Question 33

Which immunoglobulin is mainly involved in mucosal immunity? a) IgG b) IgA c) IgM d) IgD

Answer 33

Answer: b) IgA

Question 34

Which region of an antibody determines its class? a) Variable region b) Heavy chain constant region c) Light chain variable region d) Fab region

Answer 34

Answer: b) Heavy chain constant region

Question 35

What is the function of the Fc region? a) Antigen binding b) Crystallization c) Activation of immune responses d) Structural support only

Answer 35

Answer: c) Activation of immune responses

Question 36

Which immunoglobulin is produced in the spleen, tonsils, and respiratory tract? a) IgA b) IgG c) IgM d) IgE

Answer 36

Answer: d) IgE

Question 37

Which immunoglobulin is most effective in agglutination? a) IgA b) IgG c) IgM d) IgE

Answer 37

Answer: c) IgM

Question 38

What is the role of opsonization in immunity? a) Neutralizing bacterial toxins b) Marking pathogens for phagocytosis c) Destroying host cells d) Preventing antigen binding

Answer 38

Answer: b) Marking pathogens for phagocytosis

Question 39

Which immunoglobulin is least abundant in serum? a) IgA b) IgG c) IgM d) IgE

Answer 39

Answer: d) IgE

Question 40

Which immunoglobulin is responsible for immediate hypersensitivity reactions? a) IgA b) IgG c) IgM d) IgE

Answer 40

Answer: d) IgE

Question 41

What is the main function of complement fixation? a) Clot formation b) Enhancing phagocytosis and cell lysis c) Producing antibodies d) Breaking down proteins

Answer 41

Answer: b) Enhancing phagocytosis and cell lysis

Question 42

What are the two main functions of antibodies? a) Transport oxygen and store nutrients b) Bind to antigens and activate immune responses c) Replicate and undergo mitosis d) Digest proteins and break down carbohydrates

Answer 42

Answer: b) Bind to antigens and activate immune responses

Question 43

What is the importance of the hinge region in an antibody? a) It determines antibody specificity b) It allows flexibility in antigen binding c) It binds to the Fc receptor d) It is responsible for antigen degradation

Answer 43

Answer: b) It allows flexibility in antigen binding

Question 44

What is the purpose of class switching in antibodies? a) Change antigen specificity b) Alter the Fc region for different immune functions c) Prevent antigen binding d) Enhance immune suppression

Answer 44

Answer: b) Alter the Fc region for different immune functions

Question 45

Which enzyme is responsible for cleaving IgG below the hinge region? a) Trypsin b) Pepsin c) Papain d) Amylase

Answer 45

Answer: b) Pepsin

Question 46

What is an epitope? a) The entire antigen molecule b) The portion of an antigen that binds to an antibody c) The constant region of an antibody d) A type of immune cell

Answer 46

Answer: b) The portion of an antigen that binds to an antibody

Question 47

What is the role of T-helper cells in antibody production? a) Directly kill pathogens b) Activate B cells to produce antibodies c) Suppress the immune response d) Destroy red blood cells

Answer 47

Answer: b) Activate B cells to produce antibodies

Question 48

What is herd immunity? a) Immunity only in vaccinated individuals b) Protection of an entire population due to widespread immunity c) Immunity developed after infection d) Only genetic immunity

Answer 48

Answer: b) Protection of an entire population due to widespread immunity

Question 49

What is the role of an adjuvant in vaccines? a) Reduce antigen immunogenicity b) Enhance the immune response c) Destroy antibodies d) Weaken the immune system

Answer 49

Answer: b) Enhance the immune response