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Blood Serology Questions

The document outlines various aspects of blood serology, including the principles of tests like Seratec HemDirect and KM test, as well as definitions of presumptive and confirmatory tests. It discusses the composition of plasma, the high dose hook effect, and the role of forensic serology in crime scene investigations. Additionally, it highlights the limitations of the KM test and important information needed during evidence processing.

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Naveed Irshad
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128 views2 pages

Blood Serology Questions

The document outlines various aspects of blood serology, including the principles of tests like Seratec HemDirect and KM test, as well as definitions of presumptive and confirmatory tests. It discusses the composition of plasma, the high dose hook effect, and the role of forensic serology in crime scene investigations. Additionally, it highlights the limitations of the KM test and important information needed during evidence processing.

Uploaded by

Naveed Irshad
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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BLOOD SEROLOGY:

Q1. Principle of Seratec HemDirect

ANS: Add 150ul of sample added into the sample well “S”, containing mobile antibodies with bindes
to the sample having antigen and makes mobile antibody-antigen complex. This comples moves through
the absorbant card and reached at test area “T’ where it makes an antibody-antigen-antibody sandwich.
Test area T will show a pink line when haemoglobin conc. Reaches at 0.05ug/ml.

Q2. Confirmatory and presumptive test definitions

ANS: Presumptive Test: It’s a screening test used for the detection of a specific substance. Ins not a
conclusive test. Chances of false positive are always there.

Confirmatory Test: It is used to detect the presence of a specific substance in a particular


sample. It confirms the presence of a substance in sample. Less chances of false positive. More
accurate and more expensive than presumptive testing.

Q3. What is plasma?

ANS: It’s a yellowish water, major part of blood containing blood cells, proteins, sugar, fats and many
other components. It makes up 55% of the whole blood volume. Helps in maintaining blood
pressure and regulate body temp.

Q5 High Dose Hook Effect

ANS: False negative reactions can occur if the sample is too concentrated. This causes the antigen
to saturate the antibody and prevent the “antibody-antigen-antibody” sandwich formation
required for positive color detection. This is referred as the “high dose hook effect”.

Q6. What is forensic serology

ANS: It’s the detection, classification and study of various bodily fluids including, blood, semen and
saliva and their relationship to the crime scene.

Q7. Why zinc is used in KM reagent?

ANS: Zinc is used in the stock solution to keep it in reduced form.

Q8. Principle of KM test

ANS: It’s a presumptive test for blood used for the detection of blood on evidence. It’s a
phenolphthalein based test which is a clear dye, reacts with blood hemoglobin in the presence of
hydrogen peroxide and immediately turns pink.

Q9. Limitations of KM test


1. 1 in 1000 sensitivity on dried stains.
2. Eliminate the possibility of false positive in step 2 and 3
3. Does not differentiate between human and animal blood.
4. May react with chemical oxidants and vegetable peroxidases.

Q10. What information is important during processing evidence?

ANS: i. Incident Date & MLC/PMR No. and Date

ii. FIR No. & Date

iii. Description of evidence

iv. Evidence sealed or unsealed

v. Any other marking

vi. Mathing quantity of items with MLC request form.

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