Multiple Choice Questions Test - VI (Basic Periodontology).

This is a self assessment test consisting of ten questions. Click evaluate to get result.

1. 2 hours after oral prophylaxis the pellicle on lingual surfaces of teeth is approximately,

Pellicle formation starts within seconds of a clean surface being exposed to the oral environment. An equilibrium between adsorption and desorption of salivary molecules occurs after 90–120 minutes. The thickness of the pellicle is influenced by the shear forces at the site of formation. After 2 hours, the pellicle on lingual surfaces is 20–80 nm thick whereas buccal pellicles can be 200–700 nm deep.

Reference: Oral Microbiology Fifth Edition Professor Philip D Marsh.

20–80 nm thick.
80-180 nm thick.
180-400 nm thick.
400-800 nm thick.
Correct Answer - option 1

2. A highly polymorphic peptide binding region for class-I and class-II MHC molecules are

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α1 - α2 for class-I and α1 – β2 for class II
α1 - α2 for class-I and α1 - β1 for class II
α2 – α3 for class-I and α1 - β1 for class II
α1 - α2 for class-I and α2 - β1 for class II
Correct Answer - option 2

3. TNF-α binds to two receptors which are,

Upon cleavage, the released TNF-α forms a bioactive homotrimer, which then exerts its effects in an

autocrine and/or paracrine manner. The pleiotropic actions of TNF-α are mediated through two distinct cell surface receptors: TNF-α receptor-I (TNFR-I /p55) and TNF-α receptor-II (TNFR-II/p75). Only TNFR1 contains a cytoplasmic death domain and may directly induce apoptosis. TNF-α induces leukocyte adhesion molecules on endothelial cells (ECs), which mediate 3 defined steps of the inflammatory response; namely, leukocyte rolling, firm adhesion, and transmigration.

Reference: Chandrashekharan et al. Tumor necrosis factor α (TNF-α) receptor-II is required for TNF-α induced leukocyte-endothelial interaction in vivo. Blood. 2007 March 1; 109(5): 1938–1944.

Type I TNF receptor (p45) and Type II TNF receptor (p65).
Type I TNF receptor (p55) and Type II TNF receptor (p75).
Type I TNF receptor (p55) and Type II TNF receptor (p65).
Type I TNF receptor (p65) and Type II TNF receptor (p75).
Correct Answer - option 2

4. Elastase is capable of degrading,

Human neutrophil elastase is found as two isozymes named E1 and E2. These isozymes degrade Type IV collagen, laminin, fibronectin, and heparan sulfate proteoglycan similarly to each other. The degradation of such basement membrane components by elastase may assist the extravasation of neutrophils in the process of inflammation. Only type V collagen, which is susceptible to neutrophil gelatinase, is resistant to elastase. This broad substrate specificity of the enzyme may also contribute to tissue destruction at the sites of inflammation.

Reference: Hideto Watanabe et al. Human Neutrophil Elastase: Degradation of Basement Membrane Components and Immunolocalization in the Tissue. J Biochem (1990) 108 (5): 753-759.

Elastin.
Collagen.
Fibronectin.
Any of above.
Correct Answer - option 4

5. The growth of P. Gingivalis is enhanced by metabolic products of

There is synergistic relationship among various micro-organisms in a biofilm. In dental plaque we can see this relationship among various micro-organisms. Most common of these are:

  • Protoheme produced by campylobacter rectus functions as a growth factor for P. Gingivalis.
  • Formate produced by Prevotella melaninogenica which stimulates the growth of C. Rectus.

Reference: Carranza`s Clinical Periodontology  By Michael G. Newman, Henry Takei, Perry R. Klokkevold, Fermin A. Carranza

Fusobacterium which produces protoheme.
Veillonella which produces succinates.
Compylobater rectus which produces protoheme.
Compylobater rectus which produces succinates.
Correct Answer - option 3

6. The main effect of the stimulation of Toll like receptors (TLRs) is,

Tissue macrophages, mast cells and immature dendritic cells are important in initiation of immune response. Stimulation of macrophages or mast cells through their Toll-like receptors leads to the synthesis and secretion of proinflammatory cytokines and lipid mediators, thereby initiating the inflammatory response that recruits both soluble immune components and immune cells from the blood. TLR stimulation of dendritic cells induces the initiation of an adaptive immune response.

Initiation of immune response by activating T-cells.
Synthesis and secretion of pro-inflammatory cytokines and lipid mediators.
Intracellular degradation of bacteria.
None of above.
Correct Answer - option 2

7. When a mutation increases to a level involving more than 1% of population, it is referred to as,

Genetic Polymorphism is a difference in DNA sequence among individuals, groups, or populations. When a mutation increases to a level involving more than 1% of population, it is referred to as Polymorphism. Sources include SNPs, sequence repeats, insertions, deletions and recombination. (e.g. a genetic polymorphism might give rise to blue eyes versus brown eyes, or straight hair versus curly hair). Genetic polymorphisms may be the result of chance processes, or may have been induced by external agents (such as viruses or radiation). If a difference in DNA sequence among individuals has been shown to be associated with disease, it will usually be called a genetic mutation. Changes in DNA sequence which have been confirmed to be caused by external agents are also generally called "mutations" rather than "polymorphisms."

Reference: PHRMA Genomics Lexicon.

Haplotype.
Genotype.
Polymorphism.
None of above.
Correct Answer - option 3

8. Candidate genes are,

Definition of Candidate gene: Any gene thought likely to cause a disease. The gene may be a candidate because it is located in a particular chromosome region suspected of being involved in the disease or its protein product may suggest that it could be the disease gene in question.

 

Those genes which influence some key aspect of the biology involved in the disease.
Nucleotide sequences that are located at intervals along the entire genome.
Both of above.
None of above.
Correct Answer - option 1

9. The initial rolling of leukocytes during trans-endothelial migration is mediated by,

Efficient leukocyte recruitment to sites of inflammation requires the selectin family of adhesion molecules. E-, P-, and L-selectin mediate leukocyte capture and rolling on the inflamed vessel wall. Selectin-mediated leukocyte capture and rolling has been a generally accepted prerequisite for firm leukocyte adhesion and subsequent transmigration. Firm leukocyte adhesion is mediated primarily through β2 (CD18)-integrins. β2-Integrins are a family of four hetero dimers, CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1), CD11c/CD18 (p150,95), and CD11d/CD18. LFA-1 is the predominant β2-integrin on lymphocytes and neutrophils. Neutrophils also express Mac-1. Both LFA-1 and Mac-1 can interact with intercelular cell adhesion-1 (ICAM-1) expressed on resting and inflamed endothelial cells.

Reference: S. Bradley Forlow And Klaus Ley. Selectin-independent leukocyte rolling and adhesion in mice deficient in E-, P-, and L-selectin and ICAM-1.  Am J Physiol Heart Circ Physiol 280: H634–H641, 2001.

E- selectins.
L- selectins.
P- selectins.
LFA-1.
Correct Answer - option 2

10. Higher gingipain (proteolytic) activity of P. Gingivalis has been observed in,

P. gingivalis becomes more proteolytic (e.g. higher gingipain activity) in response to an increase in haemin availability, and an increase in environmental pH results in further upregulation of gingipain activity. In contrast, a high temperature results in P. Gingivalis down regulating protease activity.

Reference: Philip D. Marsh, Annette Moter & Deirdre A. Devine Dental plaque biofilms: communities, conflict and control. Periodontology 2000, Vol. 55, 2011, 16–35.

Increased haemin availability.
Increased environmental pH.
Both of above.
None of above.
Correct Answer - option 3



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