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1. Most screening tests for blood depend on the peroxidase activity of
- Haem
- Antibody
- Urine
- Protein
Answer and Explanation
Answer: (1) Haem
Explanation: Haem is an iron-containing compound that forms the non-protein part of hemoglobin and some other biological molecules.
2. A forensic scientist is supposed to answer the question when examining dried blood:
- Is it blood?
- Is it human blood?
- Which group does it belong to?
- All of the above
Answer and Explanation
Answer: (4) All of the above
Explanation: Some test that helps the forensic examiner to interpret the individuality of the person from the blood sample:
-> Luminol Test: Detection of blood samples in crime science.
-> Precipitin test: Confirmatory test for human blood.
-> Crystal test (Takayama and Teichmann): Confirmatory test for blood.
-> Protein enzyme estimation: Blood Grouping.
-> DNA Analysis: Individualization of a person with DNA fingerprinting.
Check all tests for:
-> Is it blood? (presumptive test for blood)
-> Is it human blood? (confirmatory test for blood)
3. The sequence of examination of bloodstain in chronological order is
- Benzidine test, haemin crystal test, immunological test, and elution test
- Immunological test, benzidine test, haemin crystal test, and elution test
- Elution test, immunological test, haemin crystal test, and benzidine test
- Benzidine test, elution test, haemin crystal test, and immunological test
Answer and Explanation
Answer: (1) Benzidine test, haemin crystal test, immunological test, and elution test
Explanation:
-> Benzidine— Preliminary test like luminol test
-> Haemin Crystal —Test whether the fluid is Blood or not
-> Immunological — Test to detect the presence of Antigen/Antibody
-> Elution Test — To identify the specificity of these antibodies
4. Arrange the examination method of blood in the proper sequence:
(i) Benzidine Test (ii) Teichmon Test (iii) Precipitein Test (iv) Blood grouping
- (iv), (i), (ii), (iii)
- (iv), (iii), (i), (ii)
- (i), (ii), (iii), (iv)
- (i), (ii), (iv), (iii)
Answer and Explanation
Answer: (3) (i), (ii), (iii), (iv)
Explanation:
-> Benzidine Test: preliminary test for blood
-> Teichman Test: Confirmatory test for blood
-> Precipitein Test: Confirmatory test for human blood
-> Blood Grouping: To which blood group the blood sample belongs.
5. Leucomalochite Green test is done for the examination of the following
- Urine
- Sweat
- Saliva
- Blood
Answer and Explanation
Answer: (4) Blood
Explanation: Leucomalochite Green is a presumptive test for blood that is based on the action of peroxidase activity by Hb. Hb molecules react and cleave the oxygen molecules from H2O2 (hydrogen peroxide) which catalyzes the reduced form of leucomalochite green to the oxidized form of blue-green color product.
6. Assertion (A): Luminol reacts with H2O2 to locate blood samples.
Reason (R): Because H2O2 is catalyzed by heme, though heme does not take part in the reaction
- Both (A) and (R) are correct
- Both (A) and (R) are incorrect
- (A) is correct and (R) is incorrect
- (A) is incorrect and (R) is correct
Answer
Answer: (1) Both (A) and (R) are correct
7. Gel electrophoresis is useful in the identification of the following:
- Blood
- Alkaloids
- Insecticides
- All the above
Answer and Explanation
Answer: (1) Blood
Explanation: Gel Electrophoresis is a technique that is used to isolate, identify, and characterize the properties of DNA fragments in many different situations. That’s why the correct option is blood because (in the options) blood is the only component that is used to isolate the DNA.
8. The most suitable solvent system for chromatography of blood samples is:
- Chloroform: Ethanol (40: 60)
- Methanol: Water (70: 30)
- Methanol: Acetic acid: Water (90: 3: 7)
- Ethanol: Acetic acid: Water (92: 1: 7)
Answer and Explanation
Answer: (3) Methanol: Acetic acid: Water (90: 3: 7)
9. Arrange the test methods of blood in the proper sequence:
(i) Benzidine (ii) Absorption elution (iii) Visual examination (iv) Takayama Crystal Test
- (i), (ii), (lii), (iv)
- (ii), (iii), (iv), (i)
- (iii), (i), (iv), (ii)
- (iv), (iii), (ii), (i)
Answer and Explanation
Answer: (3) (iii), (i), (iv), (ii)
Explanation:
-> Visual Examination: red color fluid
-> Benzidine Test: Preliminary blood test
-> Takayama Crystal Test: Blood confirmatory test
-> Absortion Elution: Identifies the type of Blood (ABO)
10. Assertion (A): Benzidine test is positive in blood.
Reason (R): Because of the presence of the peroxidase enzyme in the red cells.
- (A) is false but (R) is true
- (R) is false but (A) is true
- Both (A) and (R) are false
- Both (A) and (R) are true
Answer
Answer: (4) Both (A) and (R) are true
11. The following tests are used to identify blood:
(i) Florence (ii) Kastle Meyer (iii) Ptyalin test (iv) Takayama
- (i), (iii), (iv) are correct
- (ii), (iii) are correct
- (ii), (iv) are correct
- (iii), (iv) are correct
Answer and Explanation
Answer: (3) (ii), (iv) are correct
Explanation:
-> Kastle Meyer test is a presumptive blood test that is used to detect the presence of Hb in blood on reaction with phenolphthalein. Moreover, it was first described in 1903.
-> Takayama test is another blood detection test that uses pyridine to form haemo chromogen microcrystals.
12. The phenolphthalein test is used for screening of the following:
- Sweat
- Urine
- Blood
- Both Urine and Blood
Answer and Explanation
Answer: (3) Blood
Explanation: Phenolphthalein is a blood presumptive test that is based on the reaction of heme molecules of blood with phenolphthalein to impart a pink color. Phenophathelin has higher sensitivity than specificity and that’s why they can give false-positive results in the case when the sample has iron content.
13. Confirmatory tests for blood are
(i) Luminal test (ii) Hemin crystal test (iii) Wagenaar test (iv) Spectroscopic examination
- (ii), (iii) and (iv) are correct
- (i) and (iv) are correct
- (ii) and (iv) are correct
- (i) and (iii) are correct
Answer and Explanation
Answer: (1) (ii), (iii) and (iv) are correct
Explanation:
-> Wagenaar Test: also called acetone-chlor-hemin test developed in 1935.
-> Procedure: Suspected bloodstain + few drops of acetone + one drop of dil. HCl.
-> Observation: Characteristics crystals form as an indication of hemoglobin.
14. Takayama reagent consists of:
- Sodium Hydroxide, Pyridine, and Glucose
- Sodium Hydroxide, Glycerine, and Glucose
- Pyridine, Glucose and Sodium Chloride
- Sodium Chloride, Glucose, and Sucrose
Answer and Explanation
Answer: (1) Sodium Hydroxide, Pyridine, and Glucose
Explanation: In general, the Takayama reagent consists of (in 100 ml solution),
-> 65ml of distilled water
-> 20ml pyridine
-> 10ml 10% NaOH
-> 5ml 10% glucose.
Check Sensitivity, Principle, and Specificity of Takayama test
15. The preliminary examination of blood can be done by:
(i) Phenolphthalein test (ii) Precepitin test (iii) Takayama Crystal test (iv) Luminal test
- (i) and (ii) are correct
- (i) and (iv) are correct
- (ii) and (iii) are correct
- (i), (ii) and (iii) are correct
Answer and Explanation
Answer: (2) (i) and (iv) are correct
Explanation:
Phenolphthalein test and Luminal test are preliminary tests for the blood.
-> Phenolphthalein test: reacts with the heme molecule present in blood and imparts pink color
-> Luminol Test: detect trace amounts of blood as it reacts with the iron in hemoglobin up to 2 to 3 weeks.
-> Takayama Crystal test: Forms pink feathery crystals of pyridine-hemochromogen.
-> Precipitin test: To detect the presence of a specific antigen (human blood or not).
16. Arrange the following methods of blood examination in the decreasing order:
(i) Protein enzyme estimation (ii) Percipitin test (iii) Crystal test (iv) DNA analysis
- (i) (ii) (iii) (iv)
- (ii) (i) (iv) (iii)
- (iii) (ii) (iv) (i)
- (iv) (i) (ii) (iii)
Answer and Explanation
Answer: (4) (iv) (i) (ii) (iii)
Explanation:
-> DNA Analysis: Individualization of a person with DNA fingerprinting.
-> Protein enzyme estimation: Blood Grouping.
-> Percipitin test: Confirmatory test for human blood.
-> Crystal test (Takayama and Teichmann): Confirmatory test for blood.
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