BIO 250 Exam 4 V2 | BIO 250 Microbiology | Actual
Q&A with Rationale (BIO250 Exam 4) |
StraighterLine
1. Which of the following components are considered part of the human body’s first line of
defense against pathogens? (Select all that apply)
A. Intact skin, mucous membranes, and the ciliary escalator
B. Phagocytic white blood cells
C. The complement system activation
D. Inflammation and fever
E. Humoral immunity involving B-cells
F. Cell-mediated immunity involving T-cells
Correct Answer: A
Explanation: The first line of defense consists of physical and chemical barriers that
prevent entry of pathogens. Intact skin provides a tough keratinized layer, while mucous
membranes trap microbes in secretions. The ciliary escalator specifically functions in the
respiratory tract to move trapped debris away from the lungs.
2. Which period of an infectious disease is characterized by the appearance of the first mild,
non-specific signs and symptoms?
A. Incubation period
,B. Period of illness
C. Prodromal period
D. Period of decline
Correct Answer: C
Explanation: The prodromal period is the short stage following incubation where early
symptoms like malaise or aches appear. During this time, the pathogen is multiplying but
has not yet reached high enough levels to cause full-blown clinical symptoms. It is a critical
window for early detection and potential transmission.
3. A patient presents with a severe allergic reaction shortly after being stung by a bee. Which
type of hypersensitivity is being demonstrated?
A. Type II Hypersensitivity
B. Type I Hypersensitivity
C. Type III Hypersensitivity
D. Type IV Hypersensitivity
Correct Answer: B
Explanation: Type I hypersensitivity involves IgE antibodies binding to mast cells and
basophils. Upon re-exposure to the allergen, these cells degranulate and release histamine
and other mediators. This process leads to rapid symptoms ranging from hives to life-
threatening anaphylaxis.
, 4. Which antibody class is the most abundant in serum and is capable of crossing the placenta
to provide passive immunity to the fetus?
A. IgM
B. IgA
C. IgG
D. IgE
Correct Answer: C
Explanation: IgG is the primary antibody of the secondary immune response and makes
up about 80 percent of serum antibodies. It is unique among immunoglobulins for its
ability to traverse the placental barrier. This provides the newborn with essential
protection during the first few months of life while their own immune system matures.
5. The activation of the complement system results in which of the following outcomes?
A. Opsonization
B. All of the above
C. Cytolysis via the Membrane Attack Complex
D. Inflammation
Correct Answer: B
Explanation: Complement activation triggers a cascade of proteins that enhance the
immune response. Opsonization coats microbes to facilitate phagocytosis, while other
Q&A with Rationale (BIO250 Exam 4) |
StraighterLine
1. Which of the following components are considered part of the human body’s first line of
defense against pathogens? (Select all that apply)
A. Intact skin, mucous membranes, and the ciliary escalator
B. Phagocytic white blood cells
C. The complement system activation
D. Inflammation and fever
E. Humoral immunity involving B-cells
F. Cell-mediated immunity involving T-cells
Correct Answer: A
Explanation: The first line of defense consists of physical and chemical barriers that
prevent entry of pathogens. Intact skin provides a tough keratinized layer, while mucous
membranes trap microbes in secretions. The ciliary escalator specifically functions in the
respiratory tract to move trapped debris away from the lungs.
2. Which period of an infectious disease is characterized by the appearance of the first mild,
non-specific signs and symptoms?
A. Incubation period
,B. Period of illness
C. Prodromal period
D. Period of decline
Correct Answer: C
Explanation: The prodromal period is the short stage following incubation where early
symptoms like malaise or aches appear. During this time, the pathogen is multiplying but
has not yet reached high enough levels to cause full-blown clinical symptoms. It is a critical
window for early detection and potential transmission.
3. A patient presents with a severe allergic reaction shortly after being stung by a bee. Which
type of hypersensitivity is being demonstrated?
A. Type II Hypersensitivity
B. Type I Hypersensitivity
C. Type III Hypersensitivity
D. Type IV Hypersensitivity
Correct Answer: B
Explanation: Type I hypersensitivity involves IgE antibodies binding to mast cells and
basophils. Upon re-exposure to the allergen, these cells degranulate and release histamine
and other mediators. This process leads to rapid symptoms ranging from hives to life-
threatening anaphylaxis.
, 4. Which antibody class is the most abundant in serum and is capable of crossing the placenta
to provide passive immunity to the fetus?
A. IgM
B. IgA
C. IgG
D. IgE
Correct Answer: C
Explanation: IgG is the primary antibody of the secondary immune response and makes
up about 80 percent of serum antibodies. It is unique among immunoglobulins for its
ability to traverse the placental barrier. This provides the newborn with essential
protection during the first few months of life while their own immune system matures.
5. The activation of the complement system results in which of the following outcomes?
A. Opsonization
B. All of the above
C. Cytolysis via the Membrane Attack Complex
D. Inflammation
Correct Answer: B
Explanation: Complement activation triggers a cascade of proteins that enhance the
immune response. Opsonization coats microbes to facilitate phagocytosis, while other
