Which is global ecosystem ? To make its study easier it is divided into how many categories ? -

Explanation

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

1. **Understanding Global Ecosystem**: A global ecosystem refers to the largest scale of ecological organization, encompassing all the Earth's ecosystems. It includes all living organisms and their physical environment, functioning together as a unit.

2. **Categories of Global Ecosystem**: To facilitate the study of the global ecosystem, it is divided into several categories. The most common classification divides the global ecosystem into **biomes**.

3. **Number of Categories**: Generally, biomes are categorized into **terrestrial** and **aquatic** ecosystems. Terrestrial ecosystems include forests, grasslands, deserts, and tundras, while aquatic ecosystems encompass freshwater and marine environments.

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