1. Herd immunity reduces risk for all but which of the following kinds of diseas

Question

1. Herd immunity reduces risk for all but which of the following kinds of disease?
Choose one:

A. Diseases spread accidentally

B. Diseases spread by indirect transmission

C. Diseases that do not require person to person contact

D. Sexually transmitted diseases

2.

Part 1: T cells never bind to free-floating antigen. This statement is  

a. True

b. False

Part 2: T cells are activated only by antigen bound to another cell’s surface. This statement is  

True

False

Part 3: More than one type of major histocompatibility complex proteins is integral to T-cell physiology. This statement is  

True

False

3. Which of the following is true of the adaptive immune response?
Choose one:

A. B cells mostly mediate cellular immunity and T cells mostly mediate humoral immunity.

B. T cells can differentiate into antibody-secreting plasma cells.

C. A clonal population of plasma cells can produce antibodies to many different epitopes.

D. T cells can directly kill infected host cells but B cells cannot directly kill cells.

4. Which type(s) of immunity include(s) cells that are involved in the immune response to a specific antigenic epitope? Choose one or more:

A.cell-mediated

B.humoral

C.adaptive

D.innate

Explanation / Answer

1) Answer : D. Sexually transmitted diseases

Herd immunity is only for contagious diseases.

2)Answer : Part 1: true. T cells recognize only antigens which are presented.

Part 2 : True. Recognize antigen on antigen presenting cells.

Part 3 : False. It includes only APC cells like B cells

3) Answer : D. T cells can directly kill infected host cells but B cells cannot directly kill cells.

MHC class I molecules with antigen are recognized by CD8+ TC (cytotoxic) cells. Cytotoxic T cells can directly kill the infected host cell.

MHC class II molecules with antigen peptide are recognized by CD4+ TH (helper) cells. After antigen presentation, TH cells are activated to produce cytokines and in turn activates other B cells and T cells. Activated B cells differentiate to plasma cells . Plasma cells produce specific antibodies that circulate freely in the blood. Thus, the antibodies (specific) are memory antibodies which can encounter the same antigen when it enters the body again.

4) Answer : B.humoral

B-cells are involved in humoral mediated immune response in order to produce specific antibodies for specific antigen.

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