Which small structures of cell work like oars?

Answer

### Step-by-Step Solution

1. **Identify the Structures**: The small structures in cells that function similarly to oars are called **cilia**. The singular form of cilia is **cilium**.

2. **Function of Cilia**: Cilia are responsible for movement. They can either move the cell itself or help in the movement of surrounding fluids. This is analogous to how oars propel a boat through water.

3. **Structure of Cilia**: Under an electron microscope, cilia are observed to be covered by a plasma membrane. Inside, they contain a core structure known as the **axoneme**.

4. **Microtubule Arrangement**: The axoneme of cilia is characterized by a specific arrangement of microtubules known as the **9+2 arrangement**. This means there are nine pairs of microtubules arranged in a circle around two central microtubules.

5. **Connections and Sheath**: The central microtubules are connected by bridges and are enclosed by a sheath. This structural organization is crucial for the movement capabilities of cilia.

6. **Peripheral Tubules**: The peripheral microtubules in cilia are referred to as **doublets**, and they are connected by radial spokes, which help in the coordinated movement of cilia.

### Final Answer
The small structures of the cell that work like oars are called **cilia**.

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