Q.45 Given below are two statements, one is labelled as Assertion (A) and other one
labelled as Reason (R).
Assertion (A) : The application of transgenic plants are in the delayed ripening,
production of bioplastic, plant as a bioreactor for the production of antibodies, etc.
Reason (R) : Agrobacteria that carries a recombinant plasmid with both a
selectable marker and a desired transgene are used to make plant transgenic.
In light of the above statements, choose the correct answer from the options given
below.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
3. (A) is true but (R) is false.
4. (A) is false but (R) is true.
Transgenic plants enable delayed ripening (Flavr Savr tomato), bioplastic production (PHA in corn), and antibody bioreactors (tobacco plants), making (A) true. Agrobacterium with recombinant Ti plasmid (selectable marker + transgene) is the primary method for dicot transgenics, making (R) true. However, (R) describes the method, not explaining the applications in (A), so correct answer: Option 2.
Correct Answer
Option 2: Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
(A) lists established applications:
-
Delayed ripening: Flavr Savr tomato (antisense polygalacturonase)
-
Bioplastic: Transgenic corn/Arabidopsis produce PHA polymers
-
Bioreactors: Tobacco/rice express human antibodies, vaccines
(R) describes Agrobacterium-mediated transformation—T-DNA with selectable marker (nptII/kanamycin resistance) + transgene integrates into plant genome.
Why option 2? (R) explains how transgenics are made, not why they’re applied to ripening/bioplastics/antibodies.
Key Applications
| Application | Example | Gene/Mechanism |
|---|---|---|
| Delayed Ripening | Flavr Savr Tomato | Antisense PG gene → slower softening |
| Bioplastic | PHA corn | Bacterial PHA synthase genes |
| Antibody Production | Tobacco | Human IgG genes in chloroplasts |
| Bioreactor | Rice | Vaccine antigens (e.g., cholera toxin B) |
Options Analysis
| Option | A Status | R Status | Explains? | Correct? | Reason |
|---|---|---|---|---|---|
| 1 | True | True | Yes | ❌ | R=method ≠ explains applications |
| 2 | True | True | No | ✅ | Perfect: both true, independent |
| 3 | True | False | N/A | ❌ | R true (standard method) |
| 4 | False | True | N/A | ❌ | A true (all applications exist) |
Method vs Application
R (METHOD): Agrobacterium → Plant Transgenic
↓
A (APPLICATIONS): Ripening/Bioplastic/Antibodies
R enables A but doesn’t explain specific uses.
Exam Traps
-
Assuming method=explanation → Wrong (option 1)
-
Forgetting bioplastics exist → Doubt (A)
-
Thinking particle bombardment obsolete → Doubt (R)
Memory Aid: “Agro MAKES transgenics; Applications are WHAT they DO.”
Pro Tip: In AR questions, test logical linkage not just truth values. Method ≠ Purpose.
