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10. A transgenic plant having a homozygous single-copy insertion for trait A was re- transformed by Agrobacterium-mediated transformation with a gene conferring trait B. Given below are a few statements regarding the above experiment: A. All T0 transgenic plants obtained after re- transformation would be single copy events for both traits, A and B. B. T1 progeny generated by self-pollination of single- copy transgenic plants obtained by retransformation would segregate in a 3:1 ratio for trait A. C. Plant selection marker genes used for transformation experiments for both traits, A and B should be necessarily identical. Different selection marker genes cannot be used. D. 25% of T1 progeny generated by self-pollination of single-copy transgenic plants obtained by retransformation would be homozygous for both traits, A and B. Which one of the following options represents all INCORRECT statements? (1) A, C and D (2) A, B and C (3) D only (4) A and C only

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

Retransformation of a single-copy transgenic plant – segregation of traits A and B

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November 29, 2025
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A transgenic plant having a homozygous single-copy insertion for trait A was re- transformed by Agrobacterium-mediated transformation with a gene conferring trait B. Given below are a few statements regarding […]

9. Given below are some statements that are associated with transgenic plants. Each statement has a blank space indicated by '_______'. A. A transgenic plant with two functional copies of a transgene can segregate in a _______ ratio for the transgenic phenotype on self-pollination if the two genes are linked. B. The _______ system can be used for removal of marker genes from transgenic plants. C. The endogenous plant gene,_____, can be used to engineer resistance to imidazolinone herbicides. D. Variations in transgene expression levels between five independent transgenic lines generated using the same T-DNA construct can be due to _______ Which one of the following options has the correct sequence of terms that can be used to fill in the blanks in the above statements (from A to D) such that all statements become true? (1) A-9:3:3:1; B-Cre/loxP: C-ALS: D-codon usage of the transgene (2) A-3:1; B-FLP/FRT; C-bar; D-copy number of transgene (3) A-3:1; B-Cre/loxP: C-ALS; D-position effect (4) A-1:2:1; B-FLP/FRT; C-EPSPS; D-position effect

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

Key concepts in transgenic plant genetics and marker removal

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November 29, 2025
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Given below are some statements that are associated with transgenic plants. Each statement has a blank space indicated by ‘_______’. A. A transgenic plant with two functional copies of a […]

8. A To transgenic plant contains two unlinked copies of the T- DNA of which one is functional and the other is silenced. Segregation of the transgenic to non-transgenic phenotype would occur in a (i) Ratio in progeny obtained by backcrossing and in a (ii) Ration in F1 progeny obtained by self- pollination. Fill in the blanks with the correct combination of (i) and (ii) from the options given below: (1) (i) — 3:1 and (ii)— 15 : 1 (2) (i)— 1:1 and (ii) -- 3 : l (3) (i)—3:1 and (ii) —3:1 (4) (i) —1:1 and (ii) -15 : 1

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

Segregation ratios for a transgenic plant carrying two unlinked T-DNA copies

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November 29, 2025
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A To transgenic plant contains two unlinked copies of the T- DNA of which one is functional and the other is silenced. Segregation of the transgenic to non-transgenic phenotype would […]

7. Given below is a schematic representation of a Southern blot performed to identify single copy integration events of the T-DNA among six transgenic plants (T1 — T6). Which one of the following options represent potential single copy events? (1) T1, T5 and T6 (2) T2 and T3 (3) T4 only (4) T1 only

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

Identifying single-copy T-DNA insertions from a Southern blot (T₁–T₆ lines)

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November 29, 2025
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Given below is a schematic representation of a Southern blot performed to identify single copy integration events of the T-DNA among six transgenic plants (T1 — T6). Which one of […]

6. Given below is a schematic representation of the T-DNA region of a binary vector used for genetic transformation of plants. LB: Left Border, RB: Right Border, M: Marker gene, P: Passenger gene, pA: poly-adenylation signal, Pr1: promoter of M gene Pr2: Promoter of P gene, E: Restriction enzyme (sites) used for digestion of genomic DNA for Southern blotting, Probe 1 and Probe 2: probes used for Southern blotting. Transgenic plants generated using the above construct were subjected to Southern hybridization following digestion of genomic DNA with restriction enzyme 'E', to identify true single copy integration events from LB and RB flanks of the DNA. Based on the above information, the following statements are made: (A) Single copy events from the LB flank identified using Probe 1 would show two hybridization bands on THE Southern blot. (B) Single copy events from the RB flank identified using Probe 2 would show a single hybridization band on the Southern blot. (C) For true single copy events, one hybridization band would be of the same length for each of the two probes used for hybridization. (D) True single copy events would show two bands each for copy number on the left border and right border flanks. (E) There would be no similar hybridization band obtained using Probe 1 and Probe 2. Which one of the following options represents only correct statements? (1) A, B and D (2) C, D and E (3) B, C and E (4) A, C and D

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

Using Southern blot with LB/RB probes to detect true single-copy T‑DNA insertions

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November 29, 2025
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Given below is a schematic representation of the T-DNA region of a binary vector used for genetic transformation of plants. LB: Left Border, RB: Right Border, M: Marker gene, P: […]

5. Given below is a schematic representation of the T- DNA region of a transgene construct and the Southern blot analysis (using Pst l digested genomic DNA) of five independent transgenic lines (labelled as A to E) developed using the construct. The probe used for hybridization is shown as a black box below the construct (UT: Untransformed Plant) Based on the above data, which one of the following options gives the correct list of single insertion transgenic events? (1) B and C only (2) A, B and E only (3) A and B only (4) E only

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

Identifying single-copy T-DNA insertions from Southern blot patterns

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November 29, 2025
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Given below is a schematic representation of the T- DNA region of a transgene construct and the Southern blot analysis (using Pst l digested genomic DNA) of five independent transgenic […]

4. Genomic DNA of transgenic plants (P1, P2 and P3) obtained by transforming with binary vector A whose map is depicted below, was digested with BamH I and Sal I and hybridized with genomic fragment X Pattern obtained in Southern hybridization is shown below Based on the above, which of the following interpretation is correct: (1) All the plants (P1, P2 and P3) contains two copies of the transgene (2) P1, P3 contains one and P2 contains two copies of the transgene (3) P1 contains two, whereas P2 and P3 contains one copy of transgene each (4) P1 and P2 contains two and P3 contains one copy of the trangene

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

Using Southern blot patterns to estimate transgene copy number in plants

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November 28, 2025
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Genomic DNA of transgenic plants (P1, P2 and P3) obtained by transforming with binary vector A whose map is depicted below, was digested with BamH I and Sal I and […]

3. A transgenic plant is developed with the following T- DNA construct In order to analyze the nature of integration, genomic DNA digested with EcoRl was used for Southern hybridization using either probe A or B. The result obtained is as The following conclusions were made: A. There are two copies of the T-DNA cassette integrated at one loci and a third copy at another loci. B. There are two copies of the T-DNA cassette integrated at one loci. C. Complete T-DNA cassette has been integrated in all cases. D. In one T-DNA cassette there is a truncation towards the RB E. In one T-DNA cassette there is a towards the LB F. The arrangement of the T-DNA cassettes integrated at the same loci is G. The arrangement of the T-DNA cassette integrated at the same loci is Which of the above are correct? (1) B, E and G (2) B, D and F (3) A, D and F (4) B, C and F

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

Interpreting Southern blot patterns to infer T-DNA copy number, truncation and arrangement

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November 28, 2025
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A transgenic plant is developed with the following T- DNA construct In order to analyze the nature of integration, genomic DNA digested with EcoRl was used for Southern hybridization using […]

2. Given below are a few approaches/techniques used in the analysis of plants: A. Phenotype linked to the marker gene. B. PCR using primers specific to the host genome. C. Southern hybridization D. PCR using transgene-specific primers. Which one of the following combination of approaches/ techniques can be used to differentiate between transgenic and non-transgenic plants of a particular variety if the site of insertion is unknown? (1) B and C only (2) A and D only (3) A, C and D (4) A, B and C

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

How to distinguish transgenic from non-transgenic plants when the insertion site is unknown

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November 28, 2025
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Given below are a few approaches/techniques used in the analysis of plants: A. Phenotype linked to the marker gene. B. PCR using primers specific to the host genome. C. Southern […]

1. During transgenesis, the location of the genes and their number integrated into the genome of the transgenic animal are random. It is often necessary to determine the copy number of genes and their tissue-specific transcription. The following are the possible methods used for the determination. A. Polymerase Chain Reaction (PCR) B. Southern blot hybridization C. Reverse Transcriptase PCR D. Western blot Choose the correct set of combinations. (1) A and B (2) B and C (3) B and D (4) A and D

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

Methods to determine copy number and tissue-specific expression in transgenic animals

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November 28, 2025
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During transgenesis, the location of the genes and their number integrated into the genome of the transgenic animal are random. It is often necessary to determine the copy number of […]

Retransformation of a single-copy transgenic plant – segregation of traits A and B

Key concepts in transgenic plant genetics and marker removal

Segregation ratios for a transgenic plant carrying two unlinked T-DNA copies

Identifying single-copy T-DNA insertions from a Southern blot (T₁–T₆ lines)

Using Southern blot with LB/RB probes to detect true single-copy T‑DNA insertions

Identifying single-copy T-DNA insertions from Southern blot patterns

Using Southern blot patterns to estimate transgene copy number in plants

Interpreting Southern blot patterns to infer T-DNA copy number, truncation and arrangement

How to distinguish transgenic from non-transgenic plants when the insertion site is unknown

Methods to determine copy number and tissue-specific expression in transgenic animals

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