Q-1. Species identification is done by: (AIIMS May 2003)
a) Neutron activation analysis
b) Precipitin test
c) Benzidine test
d) Spectroscopy
Answer: Precipitin test
Explanation:
Presumptive tests are used at the scene, which will merely confirm that the substance in question is most likely blood, though the species is not established at this point.
Presumptive blood tests: Benzidine test, Luminol test, The Kastle-Meyer or phenolphthalein test, Leuco-malachite Green or LMG test, Hemastix (In the presence of blood, the strip will take on a green color) and Haemin crystal test (Teichmann’s test).
Important point:
The precipitin test is used to determine the species of the blood’s origin.
Q-2. Disputed maternity can be solved by using the following tests except
a) Blood grouping
b) HLA typing
c) Precipitin test
d) DNA fingerprinting
Answer: Precipitin test
Explanation:
Precipitin test is immunological method to determine whether the blood is derived from human being or from a lower animal.
Important points:
It is a specific protein test, and the reaction demonstrates the presence of aluminous substances obtained from ant part of human body.
The origin of skin, flesh, bone or even secretion such as saliva, milk and semen is determined by this test.
Q-3. Which of the following statements about blood grouping is not correct? (AIIMS NOV 2004)
a) It can be used to resolve confusion of identity in alleged exchange of babies in maternity unit
b) It is the method to conclusively fix the paternity
c) It can assist in matching fragmented human remains in mass disaster
d) It can help to show whether blood stain on the weapon belongs to the suspect or victim
Answer: It is the method to conclusively fix the paternity
Explanation:
Blood grouping may exclude a certain person as a possible father of the child but they cannot definitely establish paternity.
Q-4. What is the investigation of choice for blood grouping in old blood stain on cloth? (AIIMS May 2001)
a) Benzidine test
b) Acid dilution test
c) Haemin crystal test
d) Precipitin test
Answer: Acid dilution test
Explanation:
Presumptive tests are used at the scene, which will merely confirm that the substance in question is most likely blood, though the species is not established at this point.
Presumptive blood tests: Benzidine test, Luminol test, The Kastle-Meyer or phenolphthalein test, Leuco-malachite Green or LMG test, Hemastix (In the presence of blood, the strip will take on a green color) and Haemin crystal test (Teichmann’s test).
Important point:
The precipitin test is used to determine the species of the blood’s origin.
Q-5. Test used to detect blood group in old-blood stain from clothes is
a) Benzidine test
b) Hemin crystal test
c) Acid dilution test
d) Precipitin test
Answer: Acid dilution test
Explanation:
See above explanation.
Crack PGMEE
Q-6. Hydrogen peroxide is used in all of the following chemical tests for blood except
a) Benzidine test
b) Phenolphthalein test
c) Orthotolidine test
d) Teichmann’s test
Answer: Teichmann’s test
Explanation:
Chemical examination of blood stain:
The chemical test depends on the presence in the blood stains of an enzyme peroxidase, which in the presence of hydrogen peroxide, oxidizes the active ingredient of the reagent and produces the characteristic colored compound.
Benzidine test
Phenolphthalein test
Orthotolidine test
Leuco-malachite green test
Guaiacum test
Important point:
Haemin crystal test or Teichmann’s test: Microscopic examination
Principle of this test is to convert hemoglobin of stain into Haemin, which in presence of halogen is converted into salt and form rhombic crystals.
Q-7. Which of the following methods is used for demonstration old washed up blood- stains?
a) Infrared photography
b) Luminol stray
c) Ultraviolet light
d) Magnify lens
Answer: Luminol stray
Explanation:
Method used for demonstrating old washed-up blood stains is Luminol stray.
Luminol stray is used to locate and visualize suspected stains for presence of blood.
Q-8. For DNA testing, which tissue sample is taken in an autopsy? (AIIMS NOV 2011)
a) Liver
b) Spleen
c) Kidney
d) Brain
Answer: Spleen
Explanation:
Types of Samples Suitable for DNA Testing:
Samples collected from unidentified bodies can include: Blood, buccal swabs, hairs, bone, teeth, fingernail, tissues (Internal organs), muscle, and skin.
Important point:
Blood or splenic tissue is the best specimen for DNA analysis and should be frozen if there is likely to be any delay before the reaching laboratory.
Q-9. Blood samples for DNA finger printing are transported in
a) Saline
b) EDTA
c) NaF
d) Thymol
Answer: EDTA
Explanation:
Types of Samples Suitable for DNA Testing:
Samples collected from unidentified bodies can include: Blood, buccal swabs, hairs, bone, teeth, fingernail, tissues (Internal organs), muscle, and skin.
Blood samples for DNA finger printing:
Collected in sterile leak-proof preferably screw capped tubes containing heparin or EDTA as anticoagulant.
Important point:
Blood or splenic tissue is the best specimen for DNA analysis and should be frozen if there is likely to be any delay before the reaching laboratory.