A chromosome having more than two chromatids is called as…………….

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Chromatids**: Chromatids are the two identical halves of a duplicated chromosome. When a chromosome is replicated, it consists of two sister chromatids joined at a region called the centromere.

2. **Definition of Polytene Chromosomes**: A chromosome that has more than two chromatids is referred to as a polytene chromosome. Polytene chromosomes are characterized by the presence of multiple chromatids (often hundreds or thousands), which are formed through repeated rounds of DNA replication without cell division.

3. **Discovery and Characteristics**: Polytene chromosomes were first discovered by the scientist Balbiani in 1881. They are notably larger than typical chromosomes and can be observed under a light microscope due to their size and the banding patterns they exhibit.

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