Attention Users: Hover over to the main page of Forensic Serology MCQs for more systematic learning and solving MCQs for NTA UGC NET/JRF Forensic Science Exams preparation.
1. As per the base-pairing rule, which of the following is correct?
- A-G
- C- T
- T- G
- G- C
Answer and Explanation
Answer: (4) G- C
Explanation: The base-pair combinations are Adenine (A) — Thymine (T), and Cytosine (C) — Guanine (G). Always remember AT Goal Course.
2. The complementary base pairs among four nucleotides (A, T, G, C) areas
- A ≡ G and T = C
- A = C and G ≡ T
- A = T and G ≡ C
- All of the above
Answer and Explanation
Answer: (3) A = T and G ≡ C
Explanation: In DNA, the complementary base pairs are;
-> A = T: Adenine (A) and Thymine (T) forms two single hydrogen bonds (not a single double bond)
-> G ≡ C: Guanine (G) and Cytosine (C) forms three single hydrogen bonds.
Note: “=” and “≡” don’t represent a double bond and triple bond respectively but the number of hydrogen bonding.
3. DNA is a(n):
- Ester
- Polymer
- Enzyme
- Protein
Answer
Answer: (2) Polymer
4. Ultraviolet rays are known to damage DNA on its exposure due to
- Breaking of bonds between G and C
- Formation of thymine-thymine dimers
- Formation of primer-dimer
- Extension of non-coding regions
Answer and Explanation
Answer: (2) Formation of thymine-thymine dimers
Explanation:
-> Ultraviolet rays cause thymine base pairs to bond together into pyrimidine lesion (thymine dimer).
-> This results in the disruption in strands, which fails to reproduce.
-> That’s why 99.9% don’t reproduce, but less than 0.1% (because of reproducing ability) can cause sunburn or even skin cancers.
5. STR markers are presently preferred for forensic DNA analysis for the reasons given below, except
- It is abundant in the genome
- It is radioactive based
- It is highly amenable
- It is highly polymorphic
Answer
Answer: (2) It is radioactive based
6. Different forms of the same gene or marker are called:
- Genetic linkage
- Linkage equilibrium
- Alleles
- Locus
Answer
Answer: (3) Alleles
7. Genes that exist as alternate expressions at a particular locus is known as
- Loci
- Antigen
- Allele
- Phenotype
Answer and Explanation
Answer: (3) Allele
Explanation: Definition in simpler terms
-> Loci: plural form of locus, is a specific, fixed position on a chromosome where a particular gene or genetic marker is located.
-> Allele is a variant form of a gene located at the same position of genetic locus, on a chromosome. Humans have two alleles (are called diploid organisms) one from each parent.
-> Phenotype: are the observable characteristics of traits (height, hair color, etc.) passed between generations.
-> Genotype: genetic markup of organisms that are passed between generations.
-> Mechanism:
(1) Specific position along a chromosome= locus.
(2) Each locus is occupied by = a gene
(3) Genes in allelic form= allele
(4) Complete set of alleles= genotype
8. Structure of DNA, carrier of the genetic blueprint of all biological organisms has been reported by:
- Alec Jeffreys
- Muller
- Crick & Watson
- E.M. Southern
Answer and Explanation
Answer: (3) Crick & Watson
Explanation: In the early 1950s, Watson and Francis H.C. Crick determined the double-helix structure of DNA, the molecule containing human genes.
Reference: The Discovery of the Double Helix, 1951-1953
9. Age of bloodstain can be determined by, except:
- Colour change
- DNA
- Globulin/Albumin ratio
- Protein patterns
Answer
Answer: (2) DNA
10. The genetic markers are seen close together on the same chromosome exhibit:
- Genetic linkage
- Homozygosity
- Genetic concordance
- Independent segregation
Answer
Answer: (1) Genetic linkage
11. Short fragments of DNA labeled with a radioactive tag are known as:
- Probes
- Primers
- STR’s
- SSR’s
Answer
Answer: (1) Probes
12. DNA can be isolated from
- RBC
- WBC
- Seminal fluid
- Pure water
Answer
Answer: (2) WBC
13. Which of the following cells are not useful for DNA analysis?
- Spermatozoa
- Vaignal cells
- Red blood cells
- Buccal mucosal cells
Answer
Answer: (3) Red blood cells
14. Which of the following is used in the PCR reaction mixture?
- Ca++
- Mg++
- Li++
- Na++
Answer and Explanation
Answer: (2) Mg++
Explanation: PCR is a premixed, ready-to-use solution containing Taq DNA polymerase, dNTPs, MgCl2, and reaction buffers at optimal concentrations for efficient amplification of DNA templates by PCR. (Source)
15. The first technique that was adopted for forensic DNA analysis was:
- PCR
- STR
- RFLP
- HLA DQAI
Answer and Explanation
Answer: (3) RFLP
Explanation:
-> Restriction fragment length polymorphism (RFLP) was invented in 1984 by the English scientist Alec Jeffreysa.
-> It uses a variation of homologous DNA sequences (polymorphisms). This technique is used to distinguish individuals, populations, or species.
16. A change in one base of an amino acid sequence may produce a change, called:
- A Tetrad
- A zygote
- A point mutation
- Independent assortment
Answer and Explanation
Answer: (3) A point mutation
Explanation:
-> Tetrad: In meiosis, two homologous chromosomes formed a foursome.
-> Zygote: a fertilized egg cell produced by the union of a female gamete (egg or ovum) and a male gamete (sperm).
-> Independent assortment theory: When reproductive cells develop, different genes independently separate from one another.
17. The law of _____________ states that different segregating gene pairs behave independently due to recombination where genetic material is shuffled between generations.
- Probability
- Mendelian inheritance
- Independent assortment
- Segregation
Answer and Explanation
Answer: (3) Independent Assortment
Explanation:
-> Law of Independent Assortment states that during a dihybrid cross (crossing of two pairs of traits), an assortment of each pair of traits is independent of the other.
-> Mendelian laws state that the individuals possess two alleles that get inherited by each of the parents.
-> Segregation: separation of pairs of alleles at meiosis and their independent transmission via separate gametes.
18. The ___________controls the movement of the chromosome during cell division.
- Centromere
- Telomere
- Chromatin
- Allele
Answer and Explanation
Answer: (1) Centromere
Explanation:
-> Telomeres are the ends of eukaryotic chromosomes that contain specific DNA-protein complexes that are required to maintain chromosome integrity during the cell division cycle.
-> Chromatin is a substance within a chromosome consisting of DNA and protein.
-> Allele is a variant form of a gene.
19. Two arms composed mainly of DNA and held together by centromere is a
- Chromosome
- Protein
- Cell
- Gene
Answer
Answer: (1) Chromosome
20. Analysis of short tandem repeats is a kind of
- DNA test
- Psychometric test
- Respiratory test
- Physiological test
Answer and Explanation
Answer: (1) DNA test
Explanation:
-> Psychometric tests: used to objectively measure an individual’s personality traits, aptitude, intelligence, abilities, and behavioral style
-> Psychological test: used to measure an individual’s mental and/or. behavioral characteristics.
Note: Jump to the main page of Serology MCQs in Forensic Science.