Assertion: Members of a species are reproductively isolated from others belonging to other species.
Reason: Species is the basic taxonomic category.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that members of a species are reproductively isolated from members of other species. This means that individuals of different species cannot mate and produce viable offspring.
- For example, lions (Panthera leo) and tigers (Panthera tigris) are two different species. They cannot reproduce with each other, which supports the assertion.

2. **Analyzing the Reason**:
- The reason provided states that "species is the basic taxonomic category." This is indeed true as species is one of the fundamental levels of classification in biological taxonomy.
- The hierarchy of taxonomic categories includes: Species, Genus, Family, Order, Class, Phylum, and Kingdom.

3. **Evaluating the Truth of Both Statements**:
- Both the assertion and the reason are true statements. Members of a species are indeed reproductively isolated from other species, and species is a basic taxonomic category.

4. **Determining the Relationship**:
- Although both statements are true, the reason does not explain the assertion. The fact that species is a basic taxonomic category does not provide a reason for why members of a species are reproductively isolated from others.

5. **Conclusion**:
- Therefore, the final answer is that both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer:
Both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.

---