2025 BIO 251 Exam 3 New Latest Version Best
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Correct Answers
Which of the following statements is FALSE?
A. The Fc region determines the class of an antibody
B. Helper T-cells secrete cytokines to support B-cell production
C. Once activated, a person will continue to produce IgG for the rest of their life
D. The goal of vaccination is to prime you to have a secondary response when exposed to the
pathogen ------------ Correct Answer ------------- C. Once activated, a person will continue to
produce IgG for the rest of their life
Which of the following would display antigens on an MHC I but not an MHC II?
A. Macrophage
B. Monocyte
C. Red Blood Cell
D. Neutrophil ------------ Correct Answer ------------- D. Neutrophil
Which component of an ECG represents the AV nodal conduction time?
A) QRS complex
B) P-R interval
C) Q-T interval
D) T wave
E) T-Q segment ------------ Correct Answer ----------- B
In what phase is the cardiac cycle when all four valves are closed and pressure in the ventricle is
decreasing?
A) atrial contraction
B) ventricular filling
C) isovolumetric contraction
D) isovolumetric relaxation
E) ventricular ejection ------------ Correct Answer ----------- D
In what phase of the cardiac cycle does ventricular pressure exceed aortic pressure?
A) atrial contraction
B) ventricular filling
C) isovolumetric contraction
D) isovolumetric relaxation
E) ventricular ejection ------------ Correct Answer ----------- E
In what phase is the cardiac cycle when the A V valves are open and semilunar valves are
closed?
A) atrial contraction
,B) ventricular filling
C) isovolumetric contraction
D) isovolumetric relaxation
E) ventricular ejection ------------ Correct Answer ----------- B
In what phase is the cardiac cycle when the semilunar valves are open and A V valves are
closed?
A) atrial contraction
B) ventricular filling
C) isovolumetric contraction
D) isovolumetric relaxation
E) ventricular ejection ------------ Correct Answer ----------- E
An HIV positive individual with low CD4 T-cell count is infected with a normally non-fatal
virus and later dies. What likely occurred?
A. They were unable to generate antibodies through the T-dependent pathway due to lack of
helper T-cells
B. Their immune system became hyper-active through the T-independent pathway and they died
due to a cytokine storm
C. Their macrophages were unable to stimulate Helper T-cells due to insufficient MHCII
D. They were unable to release histamine and could not mount an inflammatory response ---------
--- Correct Answer ------------- A. They were unable to generate antibodies through the T-
dependent pathway due to lack of helper T-cells
Suppose you are observing a patient who has a bacterial infection that begins to subside fairly
quickly after becoming symptomatic. An analysis of their blood shows high levels of IgM
specific to the bacteria, but undetectable levels of IgG and IgD. Two months after being
discharged, the patient returns with another infection by the same bacteria. What would be
reasonable to conclude?
A. The patient's immune response was coordinated via cell-mediated toxicity
B. The patient is immunocompromised
C. The patient's immune reaction happened through the T-independent pathway
D. The patient did not produce sufficient antibodies to fight off the first infection ------------
Correct Answer ------------- C. The patient's immune reaction happened through the T-
independent pathway
Suppose that an antibody binds to a toxin molecule and prevents the toxin from binding to a
receptor where it would have a negative effect. This is an example of:
Immobilization
Opsonization
Neutralization
Cross-linking ------------ Correct Answer ------------- Neutralization
Which of the following is NOT a way that antibodies assist the immune system in getting rid of
pathogens?
A. Binding to viral coat proteins and preventing them from being able to enter cells
, B. Labeling pathogens for phagocytosis
C. Binding to flagella and fimbrae and preventing movement and adherence.
D. Poking holes in the cell membrane and lysing bacteria directly ------------ Correct Answer -----
-------- D. Poking holes in the cell membrane and lysing bacteria directly
Which of the following would be an example of a PAMP?
Correct answer:
A. Peptidoglycan
B. Tissue factor
C. GaGs on the surface of eukaryotic cells
D. C3b bound to bacteria ------------ Correct Answer ------------- A. Peptidoglycan
Match the antibody with the correct description
Antibody involved in allergic reactions
Antibody found abundantly in mucous secretions
First antibody produced in response to an infection
Antibody with poorly understood function
Antibody that penetrates the placenta
IgG
IgE
IgA
IgM
IgD ------------ Correct Answer ------------- Antibody involved in allergic reactions
Correct match:
IgE
Antibody found abundantly in mucous secretions
Correct match:
IgA
First antibody produced in response to an infection
Correct match:
IgM
Antibody with poorly understood function
Correct match:
IgD
Antibody that penetrates the placenta
Correct match:
IgG
What event during inflammation is responsible for swelling?
A. Vasodilation
B. Diapedesis
C. Increased sensitivity of nociceptors
D. Increasing vascular permeability ------------ Correct Answer ------------- D. Increasing vascular
permeability
Can't add this question for quizlet but know the names of the parts of phagocytosis. ------------
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