________of cell cycle can vary from organism to organism and also from cell type to cell type.

Answer

To answer the question, we need to identify the term that describes the variability of the cell cycle across different organisms and cell types. Let's break it down step by step:

### Step-by-Step Solution:

1. **Understanding the Cell Cycle**: The cell cycle is a series of phases that a cell goes through to divide and replicate. It includes stages such as interphase (which consists of G1, S, and G2 phases) and mitosis.

2. **Variability of the Cell Cycle**: The question states that the aspect of the cell cycle can vary from organism to organism and from cell type to cell type. This indicates that we are looking for a term that reflects this variability.

3. **Factors Affecting Cell Cycle Duration**: The length of the cell cycle can differ based on several factors:
- The type of organism (e.g., single-celled organisms vs. multicellular organisms).
- The specific cell type (e.g., embryonic cells vs. mature somatic cells).

4. **Examples of Variability**:
- In certain single-celled organisms, the cell cycle can be very short, lasting only a few minutes (e.g., some fly embryos).
- In contrast, in humans, the average cell cycle duration is about 24 hours.
- Some specialized cells, like liver cells, can take much longer, sometimes years, to complete a cycle.

5. **Conclusion**: Based on the understanding that the duration of the cell cycle can vary significantly among different organisms and cell types, the correct term to fill in the blank is **"duration"** or **"length"** of the cell cycle.

### Final Answer:
The **duration** of the cell cycle can vary from organism to organism and also from cell type to cell type.

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