user46241: I'm new to the biology SE but I thought that I could help answering questions about my research expertise (biophysics / neuroscience).
But I`m surprised about the questions of the type:
Can mitochondria become cancerous?
Can GMO cause Mad Cow disease and wipe out humanity?
Is it theoretically possible to safely eliminate most viruses in the atmosphere, hence preemptively cure all the viral diseases?
Should such questions be allowed?
These are similar to asking a "What if ___?" question. Are these questions not considered to be off-topic? 

user9943: Thanks for your question. 
I'll first quickly glance over your examples; 

Can mitochondria become cancerous?

Yes, it's hypothetical, but I think it is a potentially interesting question, as it has its foundations in the coupling of cell division and distribution of these mitochondria among the two daughter cells. I think it's a good question and I actually upvoted it.

Can GMO cause Mad Cow disease and wipe out humanity?

Heavily downvoted and closed in the meantime because primarily opinion-based, and I totally agree. 

Is it theoretically possible to safely eliminate most viruses in the atmosphere, hence preemptively cure all the viral diseases?

Opinion based and I closed it as such, thanks for the pointer.
So I think overall such opinion based questions should be closed, but carefully, as there might be interesting questions hidden below the post. The mitochondrion question can simply be re-phrased as

Why do mitochondrial tumors not exist? 

Or the likes and that is not a hypothetical question at all. 

46241: <p>I'm new to the biology SE but I thought that I could help answering questions about my research expertise (biophysics / neuroscience).</p>

<p>But I`m surprised about the questions of the type:</p>

<p><a href="https://biology.stackexchange.com/questions/77666/can-mitochondria-become-cancerous">Can mitochondria become cancerous?</a></p>

<p><a href="https://biology.stackexchange.com/questions/77637/can-gmo-cause-mad-cow-disease-and-wipe-out-humanity">Can GMO cause Mad Cow disease and wipe out humanity?</a></p>

<p><a href="https://biology.stackexchange.com/questions/77602/is-it-theoretically-possible-to-safely-eliminate-most-viruses-in-the-atmosphere">Is it theoretically possible to safely eliminate most viruses in the atmosphere, hence preemptively cure all the viral diseases?</a></p>

<p>Should such questions be allowed?</p>

<p>These are similar to asking a "What if ___?" question. Are these questions not considered to be off-topic? </p>
 9943: <p>Thanks for your question. </p>

<p>I'll first quickly glance over your examples; </p>

<blockquote>
  <p>Can mitochondria become cancerous?</p>
</blockquote>

<p>Yes, it's hypothetical, but I think it is a potentially interesting question, as it has its foundations in the coupling of cell division and distribution of these mitochondria among the two daughter cells. I think it's a good question and I actually upvoted it.</p>

<blockquote>
  <p>Can GMO cause Mad Cow disease and wipe out humanity?</p>
</blockquote>

<p>Heavily downvoted and closed in the meantime because <em>primarily opinion-based</em>, and I totally agree. </p>

<blockquote>
  <p>Is it theoretically possible to safely eliminate most viruses in the atmosphere, hence preemptively cure all the viral diseases?</p>
</blockquote>

<p>Opinion based and I closed it as such, thanks for the pointer.</p>

<p>So I think overall such opinion based questions should be closed, but carefully, as there might be interesting questions hidden below the post. The mitochondrion question can simply be re-phrased as</p>

<blockquote>
  <p>Why do mitochondrial tumors not exist? </p>
</blockquote>

<p>Or the likes and that is not a hypothetical question at all. </p>
