Forensic Biology and Serology

Forensic Biology and Serology

Forensic Biology and Serology Quiz Crafted by - 
Ms. Qurratul Ain Kausar Ansari
Assistant professor
Department of Forensic Science,
G H Raisoni University Amravati Maharashtra

Introduction to Forensic Biology and Serology
Forensic biology and serology is a branch of forensic science which deals with biological evidences and their examination. The examination of biological materials play an important role in connecting the criminal with the crime. Such biological specimens may be in the form of body fluids, stains or other material. Crime Laboratories routinely process evidence from criminal cases for the presence of biological fluids such as blood, semen, and saliva in order to obtain DNA profiles. Forensic Biology encompasses both Forensic Serology and DNA testing. Forensic biology division deals with the examination of biological fluids, skeletal remnants, diatoms, hair, seeds, maggots, vegetable fibres, wood etc. present in various items of evidentiary value in crime cases such as murder, attempt to murder, sexual assault and child abuse.

Let’s have a look on answers of the quiz questions along with their explanation.

Que1. The Ph of semen is in the range of
a) 7.35-7.50
b) 5.0-6.15
c) 8.03-9.00
d) None
Answer – a)7.35-7.50

Explanation - Semen or seminal fluid is an organic fluid which contains sperms or spermatozoa. It is a yellowish viscous fluid that is rich in fructose and other substances and makes up about 70% of human semen. They are slightly alkaline in nature which provides a protective environment for the sperms. The pH range of semen is normally  7.35-7.50.

Que2. The condition of low sperm count in male is  known as____
a) Aspermia
b) Oligospermia
c) Azoospermia
d) None
Answer – b) Oligospermia

Explanation - Oligospermia is a medical condition found in men, which is characterized by a low sperm count in their semen. To impregnate a woman, a healthy amount of sperm in a man's semen is usually necessary. As stated by WHO in the year 2009, if the sperm count is less than 15 million sperm per millilitre (mL), then the condition is called oligospermia.

Que3. In Christmas Tree staining the nuclei of spermatozoa present in head region turns into ____colour.
a) Blue-Green
b) Red
c) Pink
d) Green
Answer – b) Red

Explanation - The microscopic identification of spermatozoa is a method of confirming the presence of semen in an evidentiary stain. Spermatozoa are identified by either the presence of intact sperm cells displaying a head, midpiece and tail, or sperm heads showing an acrosomal cap. The microscopic examination can be enhanced by staining the slide using a differential stain known as “Christmas Tree Stain” which consists of two dyes: Nuclear Fast Red and picroindigocarmine. The red component known as Nuclear Fast Red dye  is a dye used for staining the nuclei of spermatozoa in the presence of aluminum ions. The green component, picroindigocarmine stains the neck and tail portion of the sperm. The acrosomal cap turns pink, the nucleus is red. The sperm tails stain green and the midpiece stains blue.

Que4. P30 KDa is a molecular weight of which protein?
a) PSA
b) Semenogelin I
c) Fibrinolytic
d) Semenogelin II.
Answer – a) PSA

Explanation - Like ACP, PSA (also known as p30 protein) is synthesized in the prostate under androgen control. It is present in seminal plasma at very much higher levels (>10 000×) than in any other body fluid. Due to its very low expression in other body fluids, it is routinely used as a clinical marker for the detection of prostate cancer. Given this specificity, PSA is accepted as a confirmatory marker for semen provided detected levels exceed the levels found in other body fluids.

Que5. The actual genetic section of sperm is its______
a) Neck
b) Tail
c) Middle Piece
d) Head(Nucleus)
Answer – d) Head(Nucleus)

Explanation - Head of the sperm is anterior, broad, flattened and oval structure. It consists of two parts, posterior large nucleus and anterior small cap-like acrosome. The nucleus consists of condensed DNA and basic proteins. Sperm cells contribute approximately half of the nuclear genetic information to the diploid offspring (excluding, in most cases, mitochondrial DNA). In mammals, the sex of the offspring is determined by the sperm cell: a spermatozoon bearing an X chromosome will lead to a female (XX) offspring, while one bearing a Y chromosome will lead to a male (XY) offspring.

Que6. Type  O blood group have ____ antibody on the surface of RBCs.
a) A
b) B
c) AB 
d) None
Answer – c) AB 

Explanation - ABO blood group system, the classification of human blood based on the inherited properties of red blood cells (erythrocytes) as determined by the presence or absence of the antigens A and B, which are carried on the surface of the red cells. Persons may thus have type A, type B, type O, or type AB blood. In group O the plasma contains both anti-A  and Anti-B antibodies, but the surface of the red blood cells does not contain A or B antigen. Since these antigens are not present , a person with any ABO blood type can receive O blood type.

Que7. The distribution of type  O blood in India is approximately_____
a) 7.74 % 
b) 37.13%
c) 32.26%
d) 22.88%
Answer – b)37.13%

Explanation - The most common ABO blood group type was Group B (38.6%) followed by group O (35.1%), group A (22.8%) and group AB (8.5%) respectively. The distribution of Rh(D) blood group type revealed 93.5% as Rh-positive and 6.5% as Rh-negative

 Que8. Study of interaction of antigen & antibodies found in blood is known as___
a) Histology
b) Biology
c) Serology
d) Gynecology
Answer – c) Serology

Explanation - Serology is the scientific study of serum and other body fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum. Such antibodies are typically formed in response to an infection (against a given microorganism),against other foreign proteins (in response, for example, to a mismatched blood transfusion), or to one's own proteins (in instances of autoimmune disease).

Que9. Another name for RBC's is__
a) Leukocytes
b) Erythrocytes
c) Platelets
Answer – b) Erythrocytes

Explanation - Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek erythros for "red" and kytos for "hollow vessel", with -cyte translated as "cell" in modern usage), are the most common type of blood cell and the vertebrate's principal means of delivering oxygen (O2) to the body tissues—via blood flow through the circulatory system. cell that contains hemoglobin and can carry oxygen to the body. Also called a red blood cell (RBC). The reddish color is due to the hemoglobin. Erythrocytes are biconcave in shape, which increases the cell's surface area and facilitates the diffusion of oxygen and carbon dioxide. Erythrocytes consist of hemoglobin—proteins that are responsible for the transportation of oxygen.

Que10. Where are blood cells made?
a) Bone Marrow
b) Heart
c) Liver
d) Brain
Answer –a) Bone Marrow

Explanation - Blood carries various substances that must be brought to one part of the body or another. Red blood cells are an important element of blood. Their job is to transport oxygen to the body's tissues in exchange for carbon dioxide, which is carried to and eliminated by the lungs. Red blood cells are formed in the red bone marrow of bones. Stem cells in the red bone marrow called hemocytoblasts give rise to all of the formed elements in blood. If a hemocytoblast commits to becoming a cell called a proerythroblast, it will develop into a new red blood cell. The formation of a red blood cell from hemocytoblast takes about 2 days. The body makes about two million red blood cells every second.

Que11. A stain can presumptively be identified as blood by ____
a) Amelogenin test
b) Kastle - Meyer test
c) Acid phosphatase test
d) Takayama test.
Answer –b) Kastle - Meyer test

Explanation - Phenolphthalein, a member of a class of indicators and dyes, is used in titrations of mineral and organic acids as well as most alkalis. The phenolphthalin assay for blood identification is also known as the Kastle–Meyer test. Kastle published a study in 1901, presenting the results of are action in which phenolphthalin, a colorless compound, is catalyzed by heme with hydrogenperoxide as the oxidant. The oxidized derivative is phenolphthalein, which appears pink under alkaline conditions.

Que12. Which of the following may be used for blood identification in dark room?
a) Kastle-Mayer test
b) LMG test
c) Luminol test 
d) Teichmann test
Answer – c) Luminol test

Explanation - Organic compounds whose oxidation products have chemiluminescent or fluorescent properties are utilized for testing. In the chemiluminescence assay, light is emitted as a product of a chemical reaction. In this category, luminol produces chemiluminescence when blood is present. Luminol is usually utilized as a chemiluminescent reagent. The oxidation reaction of luminol catalyzed by heme produces light in the presence of an oxidant. The light emitted from a positive reaction can only be observed in the dark, which limits the applications of luminol. The photo documentation of a luminol-enhanced pattern should be done immediately before it fades away.

Que13. In which year Teichmann documented a method in which formation of crystals in blood specimen takes place.
a) 1853
Answer –a) 1853

Explanation - Hematin Crystal Assay this assay is also known as the Teichmann crystal assay. In 1853, Teichmann documented a method of forming crystals of blood specimens. When blood specimens are treated with glacial acetic acid and salts, and subsequently heated, hematin chloride (ferriprotoporphyrin chloride), a prismatic brown-colored crystal, is formed . Hematin  is a heme derivative; its iron is in the ferric (Fe+3) state.

Que14. The crystals of pyridine ferroprotoporphyrin is formed in which blood assay____?
a) Hematin Crystal Assay
b)Takayama Crystal Assay
c) Benzidine test
d) Phenolphthalin Assay
Answer –  b) Takayama Crystal Assay

Explanation - Hemochromagens are heme derivatives in which the ferrous iron of the heme forms two bonds with nitrogenous bases. The method for forming hemochromagen crystals was documented in 1864..The Takayama crystal assay, published in 1912, has been the method preferred by many forensic laboratories. A bloodstain is treated with pyridine and glucose (a reducing sugar that is capable of reducing ferric ion) under alkaline conditions to form crystals of pyridine ferroprotoporphyrin.

Que15. The highest concentration of saliva is produced from______ gland
a) Parotids
b) Submandibular salivary gland
c) Sublingual gland 
d) Endocrine gland
Answer –  b) Submandibular salivary gland

Explanation - The human salivary glands produce 1.0–1.5 L of saliva daily. About 70% of saliva is produced from the submandibular salivary glands, 25% from the parotids, and 5% from the sublingual salivary glands. Although a continuous basal level of saliva secretion is maintained, a large amount of saliva is produced during eating. Saliva is largely water containing small quantities of electrolytes, proteins, antibodies, and enzymes.

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