DBT-BET-JRF : Previous Solved Questions

DBT-BET-JRF Questions

1. Deoxy position of deoxyribose in DNA is a

(A) 1st Carbon

(B) 3rd Carbon

(C) 2nd Carbon

(D) 5th Carbon

Ans: 2nd position

More about, log on to:DNA

2. Which of the following transgenic crops occupies the largest area in the world?

(A) Herbicide tolerant soybean

(B) Herbicide tolerant maize

(C) Insect resistant cotton

(D) Insect resistant potato

Ans: Herbicide tolerant soybean

3. The gene responsible for dwarfing character in rice is

(A) Tift 23A

(B) Norin 10

(C) Dee-geo-woo-gen

(D) Opaque 2

Ans: Dee-geo-woo-gen

4. Aroma in rice is due to

(A) Acetyl choline

(B) 4-benzyl pyrroline

(C) 2-ethyl pyrroline

(D) 2-acetyl-1-pyrroline

Ans:2-acetyl-1-pyrroline

Read more about: Aroma in Rice

5. Rifampicin is a specific inhibitor of

(A) Bacterial RNA polymerase

(B) RNA polymerase II

(C) RNA polymerase I

(D) RNA polymerase III

Ans: Bacterial RNA polymerase

Rifampin specifically inhibits bacterial RNA polymerase, the enzyme responsible for DNA transcription

More about, log on to: Protein Synthesis inhibitors

6. The Philadelphia chromosome is

(A) an example of gene amplification

(B) a product of a reciprocal translocation

(C) a characteristic of Burkitt's lymphoma

(D) an example of duplication

Ans: a product of a reciprocal translocation

Deletion of one arm of chromosome 21.
Clinical symptoms: Chronic granulocytic leukemia

7. Independently folded functional unit of a protein is called a

(A) motif

(B) fold

(C) domain

(D) module

Ans:domain

8. Most predominant antibody in serum is

(A) IgG

(B) IgD

(C) IgE

(D) IgA

Ans: IgG

IgG: Most abundant immunoglobulin, produce in the late primary response after IgM production, predominant in secondary immune response, the one and only Ig that cross placenta.
IgA: Secretory antibody, Heaviest antibody and second most abundant
IgM: Macroimmunoglobulin, pentamer, does not cross placenta, also known as natural antibody, first produced antibody upon infection.
IgD: Present on surface of B-cells and in serum.
IgE: which is responsible for allergic reactions, mediate hyper sensitivity. These are concentrated in mucous membrane, skin and lungs.

9. Scrapie is caused by

(A) Fungal protein

(B) Bacterial protein

(C) Plant lipoprotein

(D) Prion

Ans:Prion

Prion : infectious proteinaceous particles

Creutzfeld-Jacob Disease: The prion protein (PrP) is an infectious protein that converts non infectious (PrP) into infectious form, which precipitates. PrP is implicated as the causative agent of the transmissible spongioform encephalopathies, including Creutzfeld-Jacob Disease.

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10. Which one of the following organisms is used in Ames test?

(A) E. coli

(B) Streptococcus aureus

(C) Pseudomonas aerogenosa

(D) Salmonella typhimurium

Ans: Salmonella typhimurium

The Ames test

A simple and effective way to test whether a chemical is mutagenic or not.
This test uses a strain of Salmonella bacteria that has a defective histidine synthesizing gene.
The mutagenicity of the carcinogen can be quantified by counting the number of bacterial colonies that grow on a medium lacking histidine.

11. Which one of the following antibiotics attaches to 50S ribosome and inhibits peptidyl-transferase activity?

(A) Penicillin

(B) Chloramphenicol

(C) Trimethoprim

(D) Amphotericin

Ans: Chloramphenicol

More about, log on to : Mode of action of inhibitors

12. In a population of 200 individuals which is at equilibrium, the frequency of one of the alleles under study is 0.11. What is the expected frequency of heterozygous individual?

(A) 0.89

(B) 0.0979

(C) 0.1958

(D) 0.842

Ans: 0.1958

p+q=1

Take the given frequency as frequency of allele p=0.11

then q=1-0.11=0.89

Heterozygous means 2 pq ie 2x0.11x0.89=0.1958

Key points: p+q=1, p²+2pq+q²=1

For more, log on to:Population Genetics

13. To produce plants that are homozygous for all traits, the best choice is

(A) cell suspension culture

(B) callus culture

(C) anther/ pollen culture

(D) plant organ culture

Ans: anther/pollen culture

Anther culture: It is a technique by which the developing anthers at a precise and critical stage are excised aseptically from unopened flower bud and are cultured on a nutrient medium where the microspores within the cultured anther develop into callus tissue or embryoids that give rise to haploid plantlets either through organogenesis or embryogenesis.

14. Dye injected into a plant cell might be able to enter an adjacent cell through

(A) tight junction

(B) plasmodesma

(C) microtubule

(D) desmosome

Ans: plasmodesmata

cytoplasmic bridges lined with a plasma membrane that connects adjacent cells.
Functions: cell to cell communication and transport

15. If you want to use a plant tissue culture as a chemical factory for vitamins, which of the following will you choose?

(A) Suspension cultures

(B) Callus cultures

(C) Organ cultures

(D) Anther/pollen cultures

Ans: suspension culture

16. Yellow mosaic of legumes is caused by Mung bean yellow mosaic virus which belongs to

(A) Potexvirus group

(B) Potyvirus group

(C) Carlavirus group

(D) Geminiviruses group

Ans: Geminiviruses group (ss DNA viruses)

Yellow mosaic disease of legumes is caused by whitefly (Bemisia tabaci Genn.) transmitted by geminiviruses belonging to the family Geminiviridae and genus Begomovirus.

17. Antibodies which can cross placenta and are involved in allergic reactions, respectively are

(A) IgG and IgA

(B) IgM and IgE

(C) IgG and IgE

(D) IgD and IgM

Ans: IgG and IgE

IgG: Most abundant immunoglobulin, produce in the late primary response after IgM production, predominant in secondary immune response, the one and only Ig that cross placenta.
IgA: Secretory antibody, Heaviest antibody and second most abundant
IgM: Macroimmunoglobulin, pentamer, does not cross placenta, also known as natural antibody, first produced antibody upon infection.
IgD: Present on surface of B-cells and in serum.
IgE: which is responsible for allergic reactions, mediate hyper sensitivity. These are concentrated in mucous membrane, skin and lungs.

For More: Immunology Notes

18. cis-trans isomerization of the peptide bond preceding an amino acid X is known to be critical in the folding of proteins by slowing down the folding reaction. The amino acid X is

(A) isoleucine

(B) tryptophan

(C) proline

(D) Histidine

Ans:proline

Folding of proline containing polypeptides is catalyzed by peptidyl prolyl cis trans isomerase that catalyze the conversion of X-proline peptide bonds between their cis and trans conformation.
prolyl cis-trans isomerase is an accessory protein involved in protein folding.

More about, log on to : Amino acids , Protein folding

19. Which one of the following repetitive motifs is responsible for the formation of triple helix in collagen?

(A) Ala-X-Y

(B) Gly-X-Y

(C) Cys-X-Y

(D) Pro-X-Y

Ans: Gly-X-Y

Collagen consists of three polypeptide chains. It contains a repeating tripeptide sequence of Gly-X-Y, where X is often proline and Y is often hydroxy proline.

20. Pyrosequencing derives its name from the fact that

(A) the bases are detected by pyrolysis

(B) it uses enzyme apyrase to detect the bases

(C) it detects pyrophosphate released during base incorporation

(D) it generates pyrograms as output

Ans: it detects pyrophosphate released during base incorporation

More about, visit the page : Pyrosequencing

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