Which are the external conditions required for seed gemination

Options

A. Oxygen , carbon dioxide and suitable temperature
B. Oxygen, light and suitable temperature
C. Light ,moisture and suitable temeperature
D. Oxygen , moisture and suitable temperature

Answer

### Step-by-Step Solution:

1. **Water**: The first external condition required for seed germination is water. Water is essential as it helps dissolve stored food materials within the seed. It also activates enzymes that are crucial for the germination process. Additionally, water helps to remove growth inhibitors that may be present in the seeds.

2. **Air (Oxygen)**: The second condition is air, specifically the presence of oxygen. Oxygen is vital for metabolic activities that occur in the seeds. These metabolic processes, facilitated by enzymes, require oxygen to break down the stored food materials and support the growth of the seed.

3. **Temperature**: The third condition necessary for germination is a suitable temperature. Enzymatic activity and metabolic processes are highly dependent on temperature. If the temperature is too high, enzymes may degrade, halting metabolic activity. Conversely, if the temperature is too low, enzyme activity slows down significantly, which can also impede germination. Therefore, a stable and appropriate temperature is crucial for successful seed germination.

### Summary of External Conditions Required for Seed Germination:
- **Water**: Dissolves food and activates enzymes.
- **Air (Oxygen)**: Essential for metabolic processes.
- **Temperature**: Must be stable and suitable for enzyme activity.