Observe the relationship between the first two words and then fill in the suitable word at the fourth place :
centriole : 9 + 0 :: cilia: …….

Explanation

To solve the analogy presented in the question, we need to analyze the relationship between the first two terms: "centriole" and "9 + 0".

1. **Understanding Centrioles**: Centrioles are cylindrical structures found in eukaryotic cells, and they are made up of microtubules. The arrangement of microtubules in centrioles is characterized as "9 + 0", meaning there are 9 triplets of microtubules arranged in a circle, with no microtubules in the center.

2. **Understanding Cilia**: Cilia are hair-like structures that protrude from the surface of some eukaryotic cells. They are also composed of microtubules, but their arrangement differs from that of centrioles.

3. **Identifying the Arrangement of Cilia**: The structure of cilia is characterized by a "9 + 2" arrangement. This means that there are 9 outer doublets of microtubules surrounding 2 central microtubules.

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