High-Frequency PYQ Topics in BT-01
| Year | Question Topic | Key Answer | Trap Answer |
|---|---|---|---|
| NEET 2018 | Source of Taq polymerase | Thermus aquaticus | E. coli (wrong!) |
| NEET 2019 | EcoRI recognition sequence | 5'-GAATTC-3' | 5'-AAGCTT-3' (HindIII, wrong!) |
| NEET 2020 | DNA migration direction in electrophoresis | Anode (+) | Cathode (−) wrong! |
| NEET 2021 | Type of ends produced by EcoRI | Sticky ends | Blunt ends (wrong!) |
| NEET 2022 | Why Taq used in PCR | Thermostable (survives 94°C) | Has proofreading (wrong!) |
| NEET 2023 | Temperature of PCR annealing step | 50-65°C | 72°C (extension temp, wrong!) |
| NEET 2023 | Insertional inactivation in pBR322 | Foreign DNA into tetR | Foreign DNA into ampR (wrong!) |
| NEET 2024 | Ti plasmid source and use | A. tumefaciens; plant transformation | E. coli; wrong! |
| NEET 2025 | Selectable markers in pBR322 | ampR and tetR | ampR and lacZ (wrong — lacZ is pUC, not pBR322) |
Question Type Distribution (BT-01)
| Type | Frequency | Key Areas |
|---|---|---|
| Direct factual (recall) | 50% | Enzyme sources, temperatures, sequences |
| Application (diagram interpretation) | 25% | Gel patterns, plasmid maps |
| Assertion-Reason | 15% | PCR steps, electrophoresis principles |
| Multi-step reasoning | 10% | Insertional inactivation protocol, restriction analysis |
Most-Tested Single Facts:
- EcoRI recognition sequence = 5'-GAATTC-3' (tested 3 times in 5 years)
- Taq polymerase source = Thermus aquaticus (tested every 2 years)
- DNA migrates to anode in electrophoresis (tested 4 times in 7 years)
- pBR322 selectable markers = ampR and tetR (tested yearly)
- PCR temperatures: 94/50-65/72 (tested every year in some form)