The absorbed substances finally reach the tissues which utilise them for their activities. This process is called

Answer

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

1. **Understanding the Question**: The question asks about the process by which absorbed substances reach the tissues and are utilized for various activities.

2. **Identifying the Process**: The process that describes how absorbed substances are integrated and utilized by living organisms is known as "assimilation."

3. **Defining Assimilation**: Assimilation is the process through which living organisms incorporate nutrients from their environment. This involves integrating these nutrients into their biological systems.

4. **Utilization of Nutrients**: Once the nutrients are assimilated, they are converted into forms that can be used for energy and other metabolic activities. This is crucial for the growth, repair, and maintenance of tissues.

5. **Importance in Organisms**: Assimilation is essential not only for animals but also for plants. For example, nitrogen absorption and assimilation in plants is a vital process that supports their growth and development.

6. **Conclusion**: Therefore, the correct answer to the question is "assimilation."

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