Which pair of substances are used to induce shoot formation and root formation respectively during organogenesis ?

Options

A. Hydrogen peroxide and chlorine
B. Auxins and cytokinins
C. Cytokinins and auxins
D. Ethylene and abscisic acid.

Answer

To solve the question regarding which pair of substances are used to induce shoot formation and root formation respectively during organogenesis, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Organogenesis**: Organogenesis is the process by which different organs of a plant (such as roots and shoots) are formed from undifferentiated tissue known as callus.

2. **Identify the Role of Plant Hormones**: In organogenesis, specific plant hormones are crucial for inducing the formation of shoots and roots. The two main hormones involved are auxins and cytokinins.

3. **Determine the Function of Cytokinins**: Cytokinins are plant hormones that promote cell division and are primarily responsible for shoot formation. They help in the development of shoots from the callus.

4. **Determine the Function of Auxins**: Auxins are another class of plant hormones that are essential for root formation. They stimulate the growth of roots from the callus.

5. **Match the Hormones to Their Functions**: Based on the roles of these hormones:
- Cytokinins induce shoot formation.
- Auxins induce root formation.

6. **Select the Correct Pair**: The question asks for the pair of substances that induce shoot formation and root formation respectively. Therefore, the correct answer is:
- Cytokinins for shoot formation.
- Auxins for root formation.

### Conclusion:
The correct pair of substances used to induce shoot formation and root formation respectively during organogenesis is **Cytokinins (for shoot formation) and Auxins (for root formation)**.