Gene therapy frequently utilizes retroviruses, which can be engineered to deliver approximately 8000 bases of single-stranded RNA. This RNA is reverse-transcribed into DNA, integrating into the host genome, thus enabling stable expression of therapeutic genes.
| List-I | List-II |
| A. Abscisic acid | I. Promotes female flowers in cucumber |
| B. Ethylene | II. Helps seeds to withstand desiccation |
| C. Gibberellin | III. Helps in nutrient mobilisation |
| D. Cytokinin | IV. Promotes bolting in beet, cabbage etc |
| List-I | List-II |
| A. ETS Complex I | I. NADH Dehydrogenase |
| B. ETS Complex II | IV. Succinate Dehydrogenase |
| C. ETS Complex III | II. Cytochrome bc1 |
| D. ETS Complex IV | III. Cytochrome C oxidase |