Question

10. Identify the false statement regarding antigens.

A. antigens are pattern associated molecular patterns such as peptidoglycan and LPS

B. The adaptive immune system directly interacts with epitopes on an antigen

C. Can result in enhanced killing by NK cells and recognition by phagocytes

D. Only proteins can be recognized as antigens

E. A and B

F. B and C

11. Which is the correct statement regarding the complement cascade?

A. The complement cascade is considered adaptive immunity because it requires antibodies for activation

B. The classical, lectin and alternative activation pathways involve the hydrolysis of the C3 protein

C. The complement cascade promotes inflammation through the formation of the membrane attack complex

D. C5a protein is recruited and opsonizes pathogens

E. All of the above

F. None of the above

12. Which of the following is the correct association of MHC molecule recognition

A. A.CD4 recognizes MCH I on macrophages

B. CD4 recognizes MCH II on dendritic cells

C. CD8 recognizes MCH I on erythrocytes

D. CD8 recognizes MCH II on epithelial cells

13. Which of the following is true regarding phagocytosis?

A. phagocytic cells recognize antigens found on pathogens through Toll-like receptors

B. phagocytic cells completely degrade pathogens and all expel waste through exocytic vacuoles

C. Phagocytosis is an important process that allows communication between innate and adaptive immune systems

D. Monocytes and Natural Killer cells are both phagocytic cells

E. A, B and C

F. All of the above

14. Which of the following is true regarding inflammation?

A. Immediately after injury, during acute inflammation, vasodilation occurs to deliver leukocytes to the site

B. Pus is generally produced during inflammation by macrophages

C. Granulomas are pockets of infected tissue that are walled off by WBCs in acute inflammation

D. Bradykinin and histamine are cellular defenses that allow entry of WBCs and fluid into site of infection

15. Which of the following is true regarding artificial immunity?

A. Artificial immunity can only be obtained through vaccination

B. Herd immunity protects only those who can receive a vaccination

C. Live attenuated vaccines are the best because they stimulate the strongest immune response

D. Adjuvants help stimulate a stronger immune response to an antigen

16.Which of the following is true?

A. The severity of disease depends only on the activity of the pathogen

B. Primary pathogens always have higher virulence than opportunistic pathogens

C. A pathogen’s virulence is determined by it’s unique set of virulence factors

D. All of the above

E. None of the above

17. Why are Pseudomonas aeruginosa infections difficult to treat?

A. Because they are gram-positive bacteria, which are harder to treat.

B. Because they form biofilms, which are difficult for antibiotics to penetrate.

C. Because they have a special endotoxin that degrades many antibiotics.

D. Because we do not have any antibiotics that target P. aeruginosa.

18. Which of the following virulence factors are associated with invasion?

A. Biofilms

B. Glycohydrolases

C. Alpha-toxin

D. Coagulase

E. B and C

F. C and D

Answer 1

10. Antigen is any substance which when introduced parenterally into the body stimulates the production of an antibody with which it reacts specifically and in an observable manner. It can be any substance. Most naturally occurring antigens are proteins and polysaccharides like peptidoglycan and lipopolysaccharide. Lipids and nucleic acids are less Antigenic. Not all proteins are antigens. Example gelatin is non antigenic. The smallest unit of antigenicity is called epitope. Epitope can directly bind to the specific epitope receptor present on the Lymphocytes in adaptive immune response. Antigen can be directly attacked by Natural Killer cells (a class of lymphocytes) which provide a non specific defence. Antigens are also recognised by macrophages. Answer to the question is option d.

11. Classical pathway is a type of specific active immunity (adaptive immunity) whereas lectin pathway and alternative pathway are types of non specific innate immunity.

All the three pathways involve C3 hydrolysis. Membrane attack complex lyse the infected cells and promotes inflammation. C5a is not an opsonin. it is an anaphylatoxin. Options a and d are wrong whereas options b and c are correct.

12. Major histocompatibility complex (MHC) has three classes CLASS I, II, III. Class I is present on all nucleated cells (RBCs are non nucleated) and present their antigens to CD8 cells. Class II is present on only the cells of immune system like dendritic cells, macrophages, activated T cells and B cells. They present their antigens to CD4 cells. Class III is heterogeneous. Do the correct option will be option b.

13. The phagocytes recognise the antigens through Toll like receptors. This is a part of Innate immune system. There are total 13 different types of toll like receptors. Phagocytes complete destroy the cell and expel the exocytic vacuole. It is an important part in initiating the adaptive immune system. Examples of phagocytes are monocytes, macrophages, natural killer cells, histiocytes, etc. Therefore answer is all of the above.