Define the following:
PAR

Explanation

### Step-by-Step Text Solution:

1. **Definition of PAR**:
- PAR stands for Photosynthetically Active Radiation. It is a term used in the field of biology and ecology to describe a specific range of light wavelengths that are utilized by plants for photosynthesis.

2. **Spectral Range**:
- The spectral range of PAR is defined as the waveband of solar radiation that falls between 400 to 700 nanometers. This range encompasses the visible spectrum of light, which is crucial for the process of photosynthesis in autotrophic organisms.

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