Fill up the blank
Changes in our surroundings that make us respond to them, are called_______

Explanation

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

1. **Understanding the Question**: The question asks us to fill in the blank regarding changes in our surroundings that prompt a response.

2. **Identifying Key Terms**: The key terms in the statement are "changes in our surroundings" and "respond to them". These indicate that we are looking for a term that describes these changes and the reactions they provoke.

3. **Defining the Concept**: The changes in our environment that lead to a reaction or response from an organism are known as "stimuli".

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