user69: As announced in these upcoming changes to the vote to close system, we will soon be able to give custom off-topic reasons to users:

Off-topic closures will include feedback on what specifically is off-topic for that site.

Each site will have a list of its own specific pre-selected “Off-Topic” reasons
Each closer will either select one of the site's standard reasons from the list (for instance, “Recipe requests are off-topic, although recipe replacements, etc. are allowed”),
  or,
Closers can enter a free-form reason ("Your question appears to be about 'Cat Grooming', which is off-topic for Stack Overflow.")
Free-form reasons will be presented as comments, but the close dialogue will refer the reader to the comments for more info
Free-form reasons picked by closers will be available to subsequent close-voters on that question as one of the selections from the list
  These lists will be determined by the communities, and moderators will be able to update them, subject to review by each other, their community, and the SE team


Each person will be able to write their own custom feedback, however as a community we can decide on three pre-written templates.
So now we have to decide on what to have as our pre-written close notices.
Based on the advice given to moderators by the Stack Exchange team (please read in full), we need to decide on what are the most common reasons we are closing questions as off topic for, how to word them and which resources we should link to on meta (which seems like a good time as well to widen our meta knowledge base).  
If you have a suggestion for an off topic close reason, post it below.  We have a wide scope of mark-down available for formatting (no headings!) so feel free to be creative and the top three at any point in the future will be considered for activation on the site. 
Please remember the following:

Your goal here is to communicate clearly with the people whose questions are being closed, with the people who are closing questions and with the people who will later read those questions and wonder why they were closed.
At a bare minimum, off-topic reasons should identify a specific topic considered inappropriate. If you're struggling to be specific, find an example of a question that is off-topic and discuss the factors that make it inappropriate for the site.
Whenever possible, try to explain why a given topic is not allowed - this is your chance to answer the inevitable question once rather than repeating it every time a question must be closed.
Provide resources that will aid askers in solving their problems: either instructions for asking the question in a more suitable fashion, links to a different site where the question may be considered on-topic.
Be as concise as possible. Save lengthy explanations and examples for meta FAQs that can be discussed and refined over time, and then include links to these in the off-topic reasons. Don't depend on anyone following these links though; keep critical information and guidance in the reason text itself.


user3059: I'll leave it to someone else to flesh this out better:

The premise of your question relies on factually incorrect
  information, and thus, your question cannot be answered in its current form.


user69: 
Homework questions are off-topic on Biology unless you have shown your attempt at an answer.  For more information, see our homework policy.


user1590: Shopping questions... "Where can I buy X cheaply?" or "Where can I buy a good model of X?" are not biological in nature, and are thus off-topic.  For more details, please see this Biology meta answer and this blog post by Jeff Atwood.

user69: 
Personal medical questions are off-topic on Biology.  We can not safely answer questions for your specific situation and you should always consult a doctor for medical advice.


The community team have pre-populated the field with 

Requests for medical advice are off-topic here.  You should contact a qualified medical professional instead 

Is this acceptable or should we change to our own wording?  

69: <p>As announced in <a href="https://meta.stackexchange.com/questions/184154/closing-changes-on-hold-unclear-too-broad-opinion-based-off-topic-reasons/184567">these upcoming changes</a> to the vote to close system, we will soon be able to give custom off-topic reasons to users:</p>

<blockquote>
  <h3>Off-topic closures will include feedback on what specifically is off-topic for that site.</h3>
  
  <ul>
  <li>Each site will have a list of its own specific pre-selected “Off-Topic” reasons</li>
  <li>Each closer will either select one of the site's standard reasons from the list (for instance, “Recipe requests are off-topic, although recipe replacements, etc. are allowed”),
  or,</li>
  <li>Closers can enter a free-form reason ("Your question appears to be about 'Cat Grooming', which is off-topic for Stack Overflow.")</li>
  <li>Free-form reasons will be presented as comments, but the close dialogue will refer the reader to the comments for more info</li>
  <li>Free-form reasons picked by closers will be available to subsequent close-voters on that question as one of the selections from the list
  These lists will be determined by the communities, and moderators will be able to update them, subject to review by each other, their community, and the SE team</li>
  </ul>
</blockquote>

<p>Each person will be able to write their own custom feedback, however as a community we can decide on three pre-written templates.</p>

<p><strong>So now we have to decide on what to have as our pre-written close notices.</strong></p>

<p>Based on the <a href="https://meta.stackexchange.com/a/185097/176080">advice given to moderators by the Stack Exchange team</a> (please read in full), we need to decide on what are the most common reasons we are closing questions as off topic for, how to word them and which resources we should link to on meta (which seems like a good time as well to widen our meta knowledge base).  </p>

<p><strong>If you have a suggestion for an off topic close reason, post it below.  We have a wide scope of mark-down available for formatting (no headings!) so feel free to be creative and the top three at any point in the future will be considered for activation on the site.</strong>  </p>

<p>Please remember the following:</p>

<blockquote>
  <p>Your goal here is to communicate clearly with the people whose questions are being closed, with the people who are closing questions and with the people who will later read those questions and wonder why they were closed.</p>
  
  <p>At a bare minimum, <strong>off-topic reasons should identify a specific topic considered inappropriate</strong>. If you're struggling to be specific, find an example of a question that is off-topic and discuss the factors that make it inappropriate for the site.</p>
  
  <p>Whenever possible, <strong>try to explain why a given topic is not allowed</strong> - this is your chance to answer the inevitable question once rather than repeating it every time a question must be closed.</p>
  
  <p><strong>Provide resources that will aid askers in solving their problems</strong>: either instructions for asking the question in a more suitable fashion, links to a different site where the question may be considered on-topic.</p>
  
  <p><strong>Be as concise as possible</strong>. Save lengthy explanations and examples for meta FAQs that can be discussed and refined over time, and then include links to these in the off-topic reasons. Don't depend on anyone following these links though; keep critical information and guidance in the reason text itself.</p>
</blockquote>
 3059: <p>I'll leave it to someone else to flesh this out better:</p>

<blockquote>
  <p>The premise of your question relies on factually incorrect
  information, and thus, your question cannot be answered in its current form.</p>
</blockquote>
 69: <blockquote>
  <p><strong>Homework questions</strong> are off-topic on Biology <strong>unless you have shown your attempt at an answer</strong>.  For more information, see our <a href="https://biology.meta.stackexchange.com/a/267/69">homework policy</a>.</p>
</blockquote>
 1590: <p><strong>Shopping questions</strong>... "Where can I buy X cheaply?" or "Where can I buy a good model of X?" are not biological in nature, and are thus off-topic.  For more details, please see <a href="https://biology.meta.stackexchange.com/questions/424/questions-related-to-biological-models-for-educational-purpose/430#430">this Biology meta answer</a> and <a href="http://blog.stackoverflow.com/2010/11/qa-is-hard-lets-go-shopping/">this blog post by Jeff Atwood</a>.</p>
 69: <blockquote>
  <p><strong>Personal medical questions</strong> are off-topic on Biology.  We can not safely answer questions for your specific situation and you should <strong>always consult a doctor for medical advice</strong>.</p>
</blockquote>

<hr>

<p>The community team have pre-populated the field with </p>

<blockquote>
  <p>Requests for medical advice are off-topic here.  You should contact a qualified medical professional instead </p>
</blockquote>

<p>Is this acceptable or should we change to our own wording?  </p>
