Question 1
If the dilution is 1:100, and the average platelet count from both sides of the
hemacytometer counting chamber in 2 mm2 is 68, what is the calculated platelet count?
A. 680,000/mm3
B. 6,800/mm3
C. 68,000/mm3
D. 680/mm3
E. 34,000/mm3
CORRECT ANSWER
C;
A simple way to calculate platelet counts on the hemacytometer is to multiply the
average platelet count between the two sides of the chamber by 1,000. In this case 68 x
1,000 = 68,000 platelets. The longer derivation is as follows:
The standard dilution of blood for platelet counts is 1:100; therefore the dilution factor is
100. The volume of diluted blood used is based on the area and depth of the counting
area. The area counted is 1 mm2 per side (since we are using the average platelet count,
we only use the area of one side) and the depth factor is 10.
((Total number of cells counted x dilution factor x depth factor(mm)) / area in mm2) =
platelets per mm3
Question 2
Which branch of the immune system has an immediate response on first exposure to a
foreign antigenic stimulus?
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@THE STUDY VAULT
,A. Cell Mediated
B. Specific
C. Humoral
D. Innate
CORRECT ANSWER
D;
The innate immunity system is inherent and nonspecific; meaning that all pathogens are
attacked similarly. The skin, mucus in respiratory tracts, acid pH, and others are all
examples of the innate immunity system that the body has to prevent infection upon
first exposure.
Question 3
A two-year old male patient has the following hemogram results:
Hgb = 6.7gms/dl
Hct = 20%
Platelets = 355,000/ mm3
RBC = 3.0mil/cmm
WBC = 8750/cmm
Differential = 6 eos 20 segs 68 lymphs 6 monos
Which of the following is the MOST likely diagnosis?
A. Dietary iron deficiency
B. Idiopathic thrombocytopenia
C. Lymphocytic leukemia
D. Thalassemia minor
2
@THE STUDY VAULT
,E. Lead poisoning
CORRECT ANSWER
A;
We can rule out answer Idiopathic thrombocytopenia since the platelet count is normal. We
can also exclude lymphocytic leukemia because the WBC is normal. Thalassemia minor can
be excluded because thalassemia patients usually have only mild anemia. Finally, lead
poisoning cannot be the answer since this condition does not usually cause severe anemia.
The RBC, Hct, and Hgb are all very low, and this fits the picture of iron deficiency anemia.
Question 4
The purpose of C3a, C4a, C5a, the split-products of the complement cascade, is to:
The correct answer is highlighted below
bind with specific membrane receptors of lymphocytes and cause release of cytotoxic
substances.
cause increased vascular permeability, contraction of smooth muscle, and release of
histamine from basophils.
bind with membrane receptors of macrophages to facilitate phagocytosis and the
removal of debris and foreign substances.
regulate and degrade membrane cofactor protein after activation by C3 convertase.
CORRECT ANSWER
B;
The purpose of C3a, C4a, C5a, the split-products, of the complement cascade is to cause
increased vascular permeability, contraction of smooth muscle, and release of histamine
from basophils. C3a, C4a and C5a, bioactive fragments of the complement components
C3, C4 and C5, respectively play a key role in mediation of immunologically provoked
inflammatory responses. C4a production results from classical pathway activation while,
C3a and C5a are produced by the activation of the classical pathway and/or the
alternative pathway.
3
@THE STUDY VAULT
, Question 5
The protein component that surrounds the genome is called a:
A. Capsid
B. Spike
C. Co-receptor
D. Syncytia
CORRECT ANSWER
A;
The protein component that surrounds the genome is called a capsid.
Question 6
(True/False)
A centromere that is located at the point where two chromosome arms are roughly EQUAL
in length is called metacentric.
CORRECT ANSWER
True;
Metacentric centromeres are said to be near the middle of the chromosome so that the
two arms are approximately equal in length.
When the centromere is located where the two arms are not equal in length, it is
submetacentric. When the centromere is located close to one end of the chromosome
arm, it is acrocentric.
Question 7
Match the viruses below with their associated diseases.
4
@THE STUDY VAULT
If the dilution is 1:100, and the average platelet count from both sides of the
hemacytometer counting chamber in 2 mm2 is 68, what is the calculated platelet count?
A. 680,000/mm3
B. 6,800/mm3
C. 68,000/mm3
D. 680/mm3
E. 34,000/mm3
CORRECT ANSWER
C;
A simple way to calculate platelet counts on the hemacytometer is to multiply the
average platelet count between the two sides of the chamber by 1,000. In this case 68 x
1,000 = 68,000 platelets. The longer derivation is as follows:
The standard dilution of blood for platelet counts is 1:100; therefore the dilution factor is
100. The volume of diluted blood used is based on the area and depth of the counting
area. The area counted is 1 mm2 per side (since we are using the average platelet count,
we only use the area of one side) and the depth factor is 10.
((Total number of cells counted x dilution factor x depth factor(mm)) / area in mm2) =
platelets per mm3
Question 2
Which branch of the immune system has an immediate response on first exposure to a
foreign antigenic stimulus?
1
@THE STUDY VAULT
,A. Cell Mediated
B. Specific
C. Humoral
D. Innate
CORRECT ANSWER
D;
The innate immunity system is inherent and nonspecific; meaning that all pathogens are
attacked similarly. The skin, mucus in respiratory tracts, acid pH, and others are all
examples of the innate immunity system that the body has to prevent infection upon
first exposure.
Question 3
A two-year old male patient has the following hemogram results:
Hgb = 6.7gms/dl
Hct = 20%
Platelets = 355,000/ mm3
RBC = 3.0mil/cmm
WBC = 8750/cmm
Differential = 6 eos 20 segs 68 lymphs 6 monos
Which of the following is the MOST likely diagnosis?
A. Dietary iron deficiency
B. Idiopathic thrombocytopenia
C. Lymphocytic leukemia
D. Thalassemia minor
2
@THE STUDY VAULT
,E. Lead poisoning
CORRECT ANSWER
A;
We can rule out answer Idiopathic thrombocytopenia since the platelet count is normal. We
can also exclude lymphocytic leukemia because the WBC is normal. Thalassemia minor can
be excluded because thalassemia patients usually have only mild anemia. Finally, lead
poisoning cannot be the answer since this condition does not usually cause severe anemia.
The RBC, Hct, and Hgb are all very low, and this fits the picture of iron deficiency anemia.
Question 4
The purpose of C3a, C4a, C5a, the split-products of the complement cascade, is to:
The correct answer is highlighted below
bind with specific membrane receptors of lymphocytes and cause release of cytotoxic
substances.
cause increased vascular permeability, contraction of smooth muscle, and release of
histamine from basophils.
bind with membrane receptors of macrophages to facilitate phagocytosis and the
removal of debris and foreign substances.
regulate and degrade membrane cofactor protein after activation by C3 convertase.
CORRECT ANSWER
B;
The purpose of C3a, C4a, C5a, the split-products, of the complement cascade is to cause
increased vascular permeability, contraction of smooth muscle, and release of histamine
from basophils. C3a, C4a and C5a, bioactive fragments of the complement components
C3, C4 and C5, respectively play a key role in mediation of immunologically provoked
inflammatory responses. C4a production results from classical pathway activation while,
C3a and C5a are produced by the activation of the classical pathway and/or the
alternative pathway.
3
@THE STUDY VAULT
, Question 5
The protein component that surrounds the genome is called a:
A. Capsid
B. Spike
C. Co-receptor
D. Syncytia
CORRECT ANSWER
A;
The protein component that surrounds the genome is called a capsid.
Question 6
(True/False)
A centromere that is located at the point where two chromosome arms are roughly EQUAL
in length is called metacentric.
CORRECT ANSWER
True;
Metacentric centromeres are said to be near the middle of the chromosome so that the
two arms are approximately equal in length.
When the centromere is located where the two arms are not equal in length, it is
submetacentric. When the centromere is located close to one end of the chromosome
arm, it is acrocentric.
Question 7
Match the viruses below with their associated diseases.
4
@THE STUDY VAULT
