A transverse section of the truck of a tree shows concentric rings which are known as growth rings. How are these rings formed ? What is the significance of these rings ?

Explanation

### Step-by-Step Solution:

1. **Understanding Growth Rings**:
- Growth rings, also known as annual rings, are concentric circles found in the transverse section of a tree trunk. They are formed due to the secondary growth of the tree.

2. **Formation of Growth Rings**:
- The formation of these rings is associated with the activity of the cambium, a layer of meristematic tissue that is responsible for secondary growth, which increases the trunk's diameter.
- Cambial activity varies with seasons. In spring, the cambium is more active, leading to the production of a larger amount of xylem (wood) cells, which results in the formation of light-colored rings.
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