Question

the correct answers marked in bold black, can i know why the option correct and why other options is wrong. per question, write why this option is correct and explain other options are wrong. thanks

1) Which of the following is the best definition of epitope?

A) specific regions on antigens that interact with T-cell receptors (technically T-cell receptors recognize the epitope with MHC)

B) specific regions on antigens that interact with MHC class molecules**Most specific, however I will not expect you to know that much detail this semester**

C) specific regions on antigens that interact with haptens

D) specific regions on antigens that interact with antibodies

E) specific regions on antigens that interact with perforins

2) CD4 + T cells are activated by

A) interaction between CD4 + and MHC II.

B) interaction between TCRs and MHC II.

C) cytokines released by dendritic cells.

D) cytokines released by B cells.

E) complement.

3) The antibodies that can bind to large parasites are

A) IgG.

B) IgM.

C) IgA.

D) IgD.

E) IgE.

4) Which of the following statements concerning B cell receptors (BCRs) is FALSE?

A) They are formed in response to an encounter with an antigen.

B) They are complementary in shape to a specific antigenic determinant that they may or may not encounter.

C) They are bound to the surface of B lymphocytes and have two antigen-binding sites.

D) Each B lymphocyte is randomly generated with antibody variable regions that determine its BCR.

E) Scientists estimate that each person forms at least 10^11 different types of B lymphocytes with distinct BCRs.

5) The following events elicit an antibody response. What is the third step?

A) Antigen-digest goes to surface of APC.

B) APC phagocytizes antigen.

C) B cell is activated.

D) TH cell recognizes antigen-digest and MHC II.

E) TH cell produces cytokines.

Answer 1

1)Which of the following is the best definition of epitope?

In this case, you made a mistake. However is not a big deal, it can be confusing sometimes. An epitope is just a small part of an antigen. This epitopes are mostly peptide sequences. All the epitopes will be recognized by antibodies. The MHC is another type of receptor on antigen presenting cells which are going to degrade the antigen and present only the epitope to T-Cells or B-cells.

So, the correct answer is D) specific regions on antigens that interact with antibodies

2) CD4 + T cells are activated by

A) interaction between CD4 + and MHC II.

This time you are right, the MHC class II will present the exogenous antigen to the CD4 cells. On the other hand, MHC-I will present endogenous antigens to CD8 cells.

3) The antibodies that can bind to large parasites are

You are right, the correct answer is IgE. This antibody is related with allergic reactions and the immune response against pathogens such as parasites.

4) Which of the following statements concerning B cell receptors (BCRs) is FALSE?

You are right, They are formed in response to an encounter with an antigen. The BCR is formed in cells which originate in bone marrow from a common precursor.

5) The following events elicit an antibody response. What is the third step?

You are right TH cell recognizes antigen-digest and MHC II is the right answer. The first step is the recognition of the antigen by the antigen presenting cell, secondly the antigen is digested and third, it is presented.

Note: I would appreciate if you rate the question thank you.