Forensic Serology Questions and Answers

Q: The modified version of the organic extraction method that separates epithelial and sperm cells from vaginal swab is :

The method is differential extraction.Sperm heads are protected by disulphide-rich protein, so they resist lysis. In differential extraction the swab is first digested with proteinase K and detergent without a reducing agent: the vaginal epithelial cells burst, and their DNA goes into the female fraction. The intact sperm are then spun down and lysed with dithiothreitol (DTT) added, giving a male fraction. This separates the victim's and the assailant's DNA.Microwave-assisted, reflux and Soxhlet extraction are chemical extraction methods for organic compounds, not ways of separating cell types.

Q: The polymorphic markers on mitochondrial DNA can be useful in :

mtDNA markers are useful for identifying a victim by comparing samples of maternal relative DNA.Mitochondrial DNA is inherited only from the mother, without recombination, so a person shares the same mtDNA sequence (in the hypervariable regions HV1 and HV2) with the mother, siblings and other maternal relatives. When no direct reference sample of a missing person exists, mtDNA from a maternal relative can be compared with remains, which also preserve mtDNA well because each cell holds many copies.Paternity testing needs inheritance from the father, which mtDNA cannot show. 'Race recognition' is not a forensic use of these markers, and species identification relies on conserved mitochondrial genes rather than the human polymorphic markers the question describes.

Q: FUT3 gene name belongs to which of the following blood group system ?

FUT3 belongs to the Lewis blood group system.The FUT3 gene encodes a fucosyltransferase (the Lewis enzyme) that adds fucose to precursor chains, producing the Lea and Leb antigens. The antigens are made in secretions and adsorbed onto red cells from plasma, which is unusual among blood groups.The other systems have different genes: Kell is encoded by KEL, Duffy by ACKR1 (formerly DARC), and MNS by GYPA and GYPB.

Q: What do you mean by the term Teratospermia ?

Teratospermia means sperm with abnormal morphology.The prefix comes from the Greek teras, a monster or malformation. In a semen analysis it describes a sample in which the proportion of normally shaped sperm falls below the reference value (abnormal heads, midpieces or tails).The other terms are separate conditions: a low sperm count is oligospermia, no sperm in the ejaculate is azoospermia, and immobile sperm is asthenospermia (with dead sperm, necrospermia).

71.

The modified version of the organic extraction method that separates epithelial and sperm cells from vaginal swab is :

A.Differential extraction
B.Microwave assisted extraction
C.Reflux extraction
D.Soxhet extraction

Exam Year(s)

MH SET - 2025, SET Exam - 2025,

Answer: A

The method is differential extraction.

Sperm heads are protected by disulphide-rich protein, so they resist lysis. In differential extraction the swab is first digested with proteinase K and detergent without a reducing agent: the vaginal epithelial cells burst, and their DNA goes into the female fraction. The intact sperm are then spun down and lysed with dithiothreitol (DTT) added, giving a male fraction. This separates the victim's and the assailant's DNA.

Microwave-assisted, reflux and Soxhlet extraction are chemical extraction methods for organic compounds, not ways of separating cell types.

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72.

The polymorphic markers on mitochondrial DNA can be useful in :

A.Species identification
B.Race recognition
C.Paternity testing
D.Identifying a victim by comparing samples of maternal relative DNA

Exam Year(s)

MH SET - 2025, SET Exam - 2025,

Answer: D

mtDNA markers are useful for identifying a victim by comparing samples of maternal relative DNA.

Mitochondrial DNA is inherited only from the mother, without recombination, so a person shares the same mtDNA sequence (in the hypervariable regions HV1 and HV2) with the mother, siblings and other maternal relatives. When no direct reference sample of a missing person exists, mtDNA from a maternal relative can be compared with remains, which also preserve mtDNA well because each cell holds many copies.

Paternity testing needs inheritance from the father, which mtDNA cannot show. 'Race recognition' is not a forensic use of these markers, and species identification relies on conserved mitochondrial genes rather than the human polymorphic markers the question describes.

Discuss in Forum

73.

FUT3 gene name belongs to which of the following blood group system ?

A.Lewis
B.Kell
C.Duffy
D.MNS

Exam Year(s)

MH SET - 2025, SET Exam - 2025,

Answer: A

FUT3 belongs to the Lewis blood group system.

The FUT3 gene encodes a fucosyltransferase (the Lewis enzyme) that adds fucose to precursor chains, producing the Le^a and Le^b antigens. The antigens are made in secretions and adsorbed onto red cells from plasma, which is unusual among blood groups.

The other systems have different genes: Kell is encoded by KEL, Duffy by ACKR1 (formerly DARC), and MNS by GYPA and GYPB.

Discuss in Forum

74.

How many antigens are present in Diego blood group system ?

A.25
B.02
C.49
D.21

Exam Year(s)

MH SET - 2025, SET Exam - 2025,

Answer: D

The Diego system has 21 antigens, according to the figure the key uses.

The Diego system (ISBT symbol DI, system number 010) is carried on band 3, the red-cell anion exchanger AE1 encoded by SLC4A1. It includes the high-incidence antigen Di(b) and the low-incidence Di(a), which is common in East Asian and South American Indigenous populations. Standard references such as the NCBI Blood Groups and Red Cell Antigens text count 21 antigens.

The ISBT list has grown since then, and recent reviews give 22 or 23, so the number depends on the year of the source. Of the options, 25 and 49 are too many and 02 is far too few, so 21 is the only one that matches the published figure.

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75.

What do you mean by the term Teratospermia ?

A.Low sperm
B.No sperm
C.Sperm with abnormal morphology
D.Immobile and dead sperms

Exam Year(s)

MH SET - 2025, SET Exam - 2025,

Answer: C

Teratospermia means sperm with abnormal morphology.

The prefix comes from the Greek teras, a monster or malformation. In a semen analysis it describes a sample in which the proportion of normally shaped sperm falls below the reference value (abnormal heads, midpieces or tails).

The other terms are separate conditions: a low sperm count is oligospermia, no sperm in the ejaculate is azoospermia, and immobile sperm is asthenospermia (with dead sperm, necrospermia).

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