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20. In a forward genetic screen to investigate the heat stress response in Arabidopsis, a team of researchers identified an uncharacterized gene 'x' that shows some sequence homology to alpha-subunit of heterotrimeric G-protein. Since a typical alpha-subunit of heterotrimeric G-protein localizes at the membrane in a eukaryotic cell, researchers sought to validate whether the protein coded by gene 'x' localizes to membrane in tobacco protoplasts. To achieve this, they cloned the gene in fusion with GFP at its N-terminus, under the control of the CaMV promoter; however, upon expression of this GFP-gene 'x' fusion construct, they did not observe any membrane localization of GFP- signal in tobacco protoplasts. Based on this, they made a few assumptions: A. N-terminally tagging of protein 'X' with GFP may block membrane localization of protein X B. Tagging of protein 'X' with GFP may alter the conformation of protein X because of its bigger size C. Tobacco protoplasts are a heterologous system for the expression of gene 'x' and thus, the protein X does not localize to the membrane D. Gene 'x' is not getting transcribed because of the wrong promoter choice Which one of the following options represents all correct assumptions? (1) A and B only (2) B and D only (3) C and D only (4) A, B and C

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Why a GFP–fusion protein may fail to show expected membrane localization

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November 29, 2025
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In a forward genetic screen to investigate the heat stress response in Arabidopsis, a team of researchers identified an uncharacterized gene ‘x’ that shows some sequence homology to alpha-subunit of […]

19. Given below are schematic representations of the T- DNA regions of four constructs that are to be used for Agrobacterium — mediated transformation to silence an endogenous plant gene represented as XYFP that is expressed constitutively in the plant. M: Selectable marker gene expression cassette LB Left Border RB: Right Border Which of the four constructs depicted above could be used to silence the target gene XYFP? (1) A and B only (2) B and D only (3) A and C only (4) C and D only

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Choosing RNAi constructs to silence a constitutively expressed plant gene (XYFP)

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November 29, 2025
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Given below are schematic representations of the T- DNA regions of four constructs that are to be used for Agrobacterium — mediated transformation to silence an endogenous plant gene represented […]

18. In a breeding experiment; two homozygous parental lines (P1 and P2) were crossed to produce F1 hybrids. Due to an experimental error, seeds of these hybrids got mixed up with the seeds of two other germplasm lines (P3 and P4) and hybrid seeds derived from them. A marker-based fingerprinting exercise was performed using six randomly selected seeds (F1-F6) from the mixed material and the four parental lines. Results of this analysis are shown below: Based on the above data, which one of the following options represents the correct set of parents and their F1 progeny? (1) P1 X P2 = F3 (2) P3 X P4 = F2 (3) P1 X P2 = F1 (4) P3 X P4 = F6

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Using DNA fingerprint bands to identify true F₁ hybrids in a mixed seed lot

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November 29, 2025
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In a breeding experiment; two homozygous parental lines (P1 and P2) were crossed to produce F1 hybrids. Due to an experimental error, seeds of these hybrids got mixed up with […]

17. Some of the following transgenic approaches could be used for functional characterization of endogenous genes in plants: (A) Transformation using a binary vector containing a strong enhancer element and lacking the right border of T-DNA (B) Transformation using a binary vector containing a promoter-less reporter gene sequence and a selection maker gene cassette within the T-DNA. (C) Transformation using a binary vector containing only a strong enhancer element and a selection marker gene cassette within the T-DNA. (D) Transformation using a binary vector lacking a reporter gene as well as both the left and right borders of T-DNA. Which one of the following combinations can be used? (1) A and B only (2) B and C only (3) C and D only (4) A and D only

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Transgenic strategies for functional characterization of endogenous plant genes

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November 29, 2025
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Some of the following transgenic approaches could be used for functional characterization of endogenous genes in plants: (A) Transformation using a binary vector containing a strong enhancer element and lacking […]

16. In a gene stacking experiment, a transgenic plant generated using bar as a selection marker was crossed with another transgenic line containing hpt as the selection marker. Analysis of the F1 progeny of this cross showed that 50% of the progeny was resistant to both selection agents (Basta and hygromycin) while the remaining 50% of the progeny was resistant to only hygromycin. Which one of the following statements is a possible explanation of the above results? (1) Both the transgenic lines used as parents for the cross are single-copy events that are homozygous for the transgenes. (2) The Basta-resistant transgenic plant is a single- copy, homozygous event and the hygromycin- resistant plant is a double-copy event that is homozygous for two unlinked copies of the transgene. (3) The bar containing transgenic plant is a hemizygous single-copy event and the hpt containing transgenic plant is a homozygous, single-copy event (4) Both the transgenic plants used as parents for the cross are hemizygous, single-copy

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Explaining a 1:1 segregation of double resistance in a gene stacking cross

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November 29, 2025
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In a gene stacking experiment, a transgenic plant generated using bar as a selection marker was crossed with another transgenic line containing hpt as the selection marker. Analysis of the […]

15. A single copy homozygous transgenic plant containing the transgene 'A' for fungal resistance was subsequently re-transformed with another gene ' B' for conforming resistance to salt stress. The selection marker genes used for both the transformation experiment were different. Transgenic plant obtained following the retransformation experiment were screened for salt stress resistance and single copy event were identified by southern hybridization. These single copy event were self - pollinated. In the event of the two T-DNA (containing the A and B transgenes) getting integrated in unlinked location in all transgenic plants, the phenotypic ratios among the T1 progeny would be: (1) 3 (fungal resistant + salt- stress resistant): 1(fungal resistant) (2) 1 (fungal resistant): 2 (fungal resistant + salt resistant): 1(salt- stress resistant) (3) 3 (salt -stress resistant): 1 (fungal resistant) (4) 1 (fungal resistant) :1(salt- stress resistant): 1(fungal resistant+ salt stress resistant)

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Segregation of two independent transgenes for fungal and salt-stress resistance

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November 29, 2025
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A single copy homozygous transgenic plant containing the transgene ‘A’ for fungal resistance was subsequently re-transformed with another gene ‘ B’ for conforming resistance to salt stress. The selection marker […]

14. Which one of the following statements is correct? (1) If a transgenic plant heterozygous for an insert segregates into 1:1 ratio for the transgenic phenotype on back-crossing then it contains two unlinked copies of the insert. (2) ANOVA allows a plant breeder to test whether measurements from three or more treatments show statistically significant differences. (3) Comparative genomics allows scientists to identify regions of collinearity but not synteny between different species. (4) For genetic mapping of a quantitative trait in plants, an RIL mapping population comprising of individuals that are heterozygous at most loci is preferred.

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Understanding ANOVA, segregation ratios, synteny vs collinearity, and RILs in plant genetics

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November 29, 2025
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Which one of the following statements is correct? (1) If a transgenic plant heterozygous for an insert segregates into 1:1 ratio for the transgenic phenotype on back-crossing then it contains […]

13. Which one of the following statements related to genetic transformation of plants is correct? (1) Negative selection markers need to be expressed only under strong constitutive promoter development of transgenic plants (2) A transgenic plant containing two linked copies of the transgene in heterozygous condition would segregate in a 3:1(transgenic: non- transgenic) ratio for the transgenic phenotype on pollination. (3) Agrobacterium -mediated transfer of T-DNA into a host plant does not require host plant proteins. (4) In a binary vector system of Agrobacterium tumefaciens, the oncogenes are located on the Helper plasmid.

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Key facts about plant transformation, segregation, and Agrobacterium binary vectors

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November 29, 2025
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Which one of the following statements related to genetic transformation of plants is correct? (1) Negative selection markers need to be expressed only under strong constitutive promoter development of transgenic […]

12. ATO transgenic plant containing a transgene for herbicide resistance shows two bands on Southern blot analysis using a probe that is internal to the restriction sites used for genomic DNA digestion. However, it segregates in a 3: 1 ratio for herbicide resistance: sensitivity in the T1 progeny obtained by self- pollination. Which one of the following statements is correct? (1) The T0 plant is a single-copy event (2) The T0 plant is a double-copy event and the two transgene copies are tightly linked (3) The T0 plant is a double-copy event and the two transgene copies are integrated in two different chromosomes (4) The T0 plant contains two unlinked copies of the transgene, both of which are truncated versions of the herbicide resistance gene.

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Interpreting Southern blot and segregation data for herbicide‑resistant transgenic plants

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November 29, 2025
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ATO transgenic plant containing a transgene for herbicide resistance shows two bands on Southern blot analysis using a probe that is internal to the restriction sites used for genomic DNA […]

11. Given below are four statements regarding genetic transformation of plants in the laboratory: (A) Plants incapable of sexual reproduction cannot be transformed by Agrobacterium tumefaciens (B) Integration of transgene in organellar (chloroplast) genome occurs primarily by homologous recombination (C) An enhancer trap construct used in Agrobacterium- mediated transformation would contain a functional coding sequence of a reporter gene and a minimal promoter (D) A T0 transgenic plant containing two unlinked copies of a selection marker gene (hpt) and one copy of the passenger gene (gfp) would segregate in a 1 : 1 ratio for hygromycin resistance: sensitivity in the backcrossed progeny grown on selection media Which one of the combinations of above statements are correct? (1) A and D (2) B and C (3) A and C (4) B and D

CSIR NET Life Science Previous Year Questions and Solution on applied biology

Key facts about plant transformation, chloroplast integration, enhancer traps, and segregation of marker genes

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November 29, 2025
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Given below are four statements regarding genetic transformation of plants in the laboratory: (A) Plants incapable of sexual reproduction cannot be transformed by Agrobacterium tumefaciens (B) Integration of transgene in […]

Why a GFP–fusion protein may fail to show expected membrane localization

Choosing RNAi constructs to silence a constitutively expressed plant gene (XYFP)

Using DNA fingerprint bands to identify true F₁ hybrids in a mixed seed lot

Transgenic strategies for functional characterization of endogenous plant genes

Explaining a 1:1 segregation of double resistance in a gene stacking cross

Segregation of two independent transgenes for fungal and salt-stress resistance

Understanding ANOVA, segregation ratios, synteny vs collinearity, and RILs in plant genetics

Key facts about plant transformation, segregation, and Agrobacterium binary vectors

Interpreting Southern blot and segregation data for herbicide‑resistant transgenic plants

Key facts about plant transformation, chloroplast integration, enhancer traps, and segregation of marker genes

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