user389: This is a good question. Are we obliged to answer it?

user66: Good question? Yes.
The question is clearly formatted and clearly presents the attempts for finding an answer. So, this is a perfectly valid question for the SO in general and SO.Biology in particular.
Obliged? No.
Nobody is obliged to answer any questions. If you feel you can answer it -- just go ahead. But SO is a community project and everything is purely volunatarily.
Restrictions on homework questions
Referencing to the comment by Mad Scientist I see the following options possible:
Answer proposal: Every "homework" question is expected to have a suggested answer from the asker, which can be right or wrong, but it should be comprehensive enough to show the presence of some basic knowledge on the topic.
Staging:
The answer is given 3-7 days after the question was asked. Given this rule it becomes useful to ask questions for the classes that take place in shorter than a week.

389: <p><a href="https://biology.stackexchange.com/q/1627/389">This</a> is a good question. Are we obliged to answer it?</p>
 66: <p><strong>Good question? Yes.</strong></p>

<p>The question is clearly formatted and clearly presents the attempts for finding an answer. So, this is a perfectly valid question for the SO in general and SO.Biology in particular.</p>

<p><strong>Obliged? No.</strong>
Nobody is obliged to answer any questions. If you feel you can answer it -- just go ahead. But SO is a community project and everything is purely volunatarily.</p>

<p><strong>Restrictions on homework questions</strong>
Referencing to the comment by <a href="https://biology.meta.stackexchange.com/users/6/mad-scientist">Mad Scientist</a> I see the following options possible:</p>

<p><em>Answer proposal</em>: Every "homework" question is expected to have a suggested answer from the asker, which can be right or wrong, but it should be comprehensive enough to show the presence of some basic knowledge on the topic.</p>

<p><em>Staging</em>:
The answer is given 3-7 days after the question was asked. Given this rule it becomes useful to ask questions for the classes that take place in shorter than a week.</p>
