Questions Set-3: Forensic Biology

FORENSIC BIOLOGY

Q1. Urea suspected in urine stain is detected with

a.      Urease-bromothymol blue paper
b.      Litmus paper
c.       pH meter
d.      Colorimeter

ANSWER:

a. Urease- Bromothymol blue paper

EXPLANATION:

Urea, a compound found in urine, can be detected using a urease-bromothymol blue paper test.

Urease is an enzyme that catalyzes the hydrolysis of urea into ammonia and carbon dioxide.

Bromothymol blue is a pH indicator that changes color in the presence of ammonia.

Q2. Match the following:

LIST I		LIST II
A.	Phenolphthalein assay	I.	When oxidized and catalysed by heme, it emits an intense yellowish-green light
B.	Benzidine assay	II.	It is catalysed by heme with hydrogen peroxide as the oxidant
C.	Fluorescein assay	III.	These are heme derivatives in which ferrous iron of the heme forms two bonds with nitrogenous bases
D.	Hemochromagen crystal assay	IV.	It is catalysed by heme to produce blue to dark blue color.

Codes:

a.      A-II, B-III, C-I, D-IV
b.      A-I, B-III, C-IV, D-II
c.       A-II, B-IV, C-I, D-III
d.      A-IV, B-I, C-II, D-III

ANSWER:

c. A-II, B-IV, C-I, D-III

Q3. Identify the correct sequence in which techniques of DNA analysis have been developed

A.      D1S80
B.      HLA-DQ a
C.      STR
D.     mt DNA
Codes
a.      A, B, C, D
b.      B, C, A, D
c.       B, A, C, D
d.      C, A, B, D

ANSWER:

c. B, C, A, D

EXPLANATION:

HLA-DQ alpha was developed in the 1980s and was one of the earliest DNA typing techniques used in forensic analysis.

STR (Short Tandem Repeat) analysis gained prominence in the late 1980s and early 1990s. It became the standard method for DNA profiling in forensic science due to its high discrimination power and reliability.

D1S80 is another DNA marker used in forensic analysis. It was developed after STR analysis but before the use of mtDNA analysis became widespread.

mtDNA (mitochondrial DNA) analysis has been used in forensic analysis since the 1990s, but it became more prominent in the early 2000s. It is typically used when nuclear DNA is degraded or unavailable.

Q4. Assertion (A): the spliced mRNA form is produced which is used for protein synthesis.

Reason (R): because in splicing, the introns are removed and the exons are joined

a. Both A and R are correct and R is the correct explanation of A

b. Both A and R are correct but R is NOT the correct explanation of A

c. A is correct but R is false.

d. A is false but R is correct.

ANSWER:

a. Both A and R are correct and R is the correct explanation of A

EXPLANATION:

During RNA splicing, introns (non-coding regions) are removed from the pre-mRNA molecule, and the exons (coding regions) are joined together to form the mature mRNA molecule. This spliced mRNA contains only the coding regions necessary for protein synthesis.

Q5. The enzyme glyoxalase is present in

a.      Only blood
b.      Both blood and semen
c.       Only semen
d.      Only hair

ANSWER:

b. Both blood and semen

EXPLANATION:

Glyoxalase is an enzyme involved in the detoxification of methylglyoxal, a cytotoxic compound formed as a byproduct of metabolism. It plays a crucial role in protecting cells from the harmful effects of methylglyoxal.

The enzyme glyoxalase is found in various bodily fluids and tissues, including blood and semen. In blood, it is involved in detoxifying methylglyoxal to prevent cellular damage, while in semen, it may play a role in protecting sperm cells from oxidative stress and damage.

Q6. PCR techniques were invented by

a.      Alec Jeffery
b.      Karry Mullis
c.       John Buttler
d.      L. Kobilinsky

ANSWER:

b. Karry Mullis

Q7. Allele frequency in population genetics using DNA analysis is calculated to

a.      Counter the stutter bands
b.      Count the number of times each allele is observed
c.       Count the number of markers used
d.      Count the number of dyes used

ANSWER:

c. Count the number of times each allele is observed

EXPLANATION:

In population genetics using DNA analysis, allele frequency refers to the proportion of each allele within a population. It is calculated by counting the number of times each allele is observed in a sample population and then dividing by the total number of alleles observed.

Q8. Takayama test, ferrous ion from haemoglobin reacts with pyridine to produce

a.      Red rhombic crystals
b.      Red feathery crystals
c.       Red circular crystals
d.      Brown feathery crystals

ANSWER:

d. Brown Feathery crystals

EXPLANATION:

The Takayama test is used to detect the presence of bloodstains. In this test, ferrous ions from hemoglobin react with pyridine

Q9. Triangular cross section is seen in which type of hair

a.       Eyelashes
b.      Eyebrows
c.       Scalp hair
d.      Beard hair

ANSWER:

d. Beard hair

EXPLANATION:

Beard hair often has a triangular cross-section, which gives it a coarse and wiry texture. This triangular shape contributes to the stiffness and strength of beard hair, which is necessary to support the growth of facial hair. In contrast, eyelashes, eyebrows, and scalp hair typically have a more cylindrical or oval cross-section.

Q10. The hard outer layer of a pollen grain is made of

a.       Sporopollenin
b.      Chitin
c.       Silica
d.      Pectin

ANSWER:

a. Sporopollenin

EXPLANATION:

Sporopollenin is a complex organic polymer found in the outer layer of pollen grains as well as spores of ferns, fungi, and some other plants. It is highly resistant to decay and provides protection to the delicate reproductive cells inside the pollen grain. This outer layer helps pollen grains withstand various environmental conditions, such as desiccation, UV radiation, and microbial attack, allowing them to be transported from the male reproductive organ (anther) to the female reproductive organ (stigma) of flowers for pollination.