user22057: Current homework policy is to allow questions where the user has shown evidence of trying to answer the question. This is reasonable if there is a definite biological question, the answer to which may be of more general interest. And that is the crux: this site should be about explaining or discussing biology of general interest.
However if a student posts an MCQ there is no general biological question involved. An MCQ is designed (often badly) to test a student's understanding of a concept. It may be amusing for the more knowledgeable of us to see what trick an instructor is trying to play, and to demonstrate our ‘cleverness’ in answering, but in doing so we are going against the objectives of Biology StackExchange and discouraging anyone seriously interested in Biology to participate. As a quite recent contributor (more used to the standards of Stack Overflow) this is certainly the impression I get from the toleration of such questions.
I propose that the policy on homework questions be changed so that any MCQ posted on Biology StackExchange be automatically disallowed. 
This need not prevent the topic being aired if there is one and the poster has shown some evidence of effort. The moderator could edit the question appropriately, removing it from the MCQ format. Consider the hard case of:

Which of the following lacks DNA? a) An Enucleated ovum b) Mature RBC c) A mature spermatozoan d) Hair root

where the poster says that he thinks the answer may be a) or b) and explains his uncertainty (showing effort).
One could rephrase the question in the form:

Are there any cells in the human body that lack DNA? I can think of two but I'm not sure...

PS
And if this does not appear to qualify as a question, then I am asking “Is there support for this suggestion and, if so, how can the policy be changed to implement it.” 

user3827: As answers are supposed to be well researched and citing sources, a bad multiple choice question might still prompt an interesting, well structured answer explaining not only which is the right choice and why but also why the wrong choices are wrong. 
Determining what could have been the 'pitfall' or 'trick' the instructor was trying to play can actually help the student and other people struggling with the underlying biology. For example with the example you were using there was a wonderful comment explaining, why the enucleated ovum is wrong and how someone could be mislead, effectively teaching people not to forget about mitochondrial DNA. 
Re-formating the question with the "I can think of two..." option actually might prompt less valuable answers, as they will not explain, why the other two options given are wrong. 
If we allow homework questions (of course with an attempt to answer), because they can lead to a nice collection of basic answers useful for people who might not generally contribute to the site but ended up here via google, I guess allowing multiple choice questions serves the same purpose.
If the question is clearly stated and all options are given, the problem is more in the quality and extend of answers (maybe only explaining what is right, not what is wrong) than in the question. You can quite often learn more if you are told what is wrong and why, then just memorising what is right.

22057: <p>Current homework policy is to allow questions where the user has shown evidence of trying to answer the question. This is reasonable if there is a definite biological question, the answer to which may be of more general interest. And that is the crux: this site should be about explaining or discussing biology of general interest.</p>

<p>However if a student posts an MCQ there is no general biological question involved. An MCQ is designed (often badly) to test a student's understanding of a concept. It may be amusing for the more knowledgeable of us to see what trick an instructor is trying to play, and to demonstrate our ‘cleverness’ in answering, but in doing so we are going against the objectives of Biology StackExchange and discouraging anyone seriously interested in Biology to participate. As a quite recent contributor (more used to the standards of Stack Overflow) this is certainly the impression I get from the toleration of such questions.</p>

<p><em>I propose that the policy on homework questions be changed so that any MCQ posted on Biology StackExchange be automatically disallowed.</em> </p>

<p>This need not prevent the topic being aired if there is one and the poster has shown some evidence of effort. The moderator could edit the question appropriately, removing it from the MCQ format. Consider the hard case of:</p>

<blockquote>
  <p>Which of the following lacks DNA? a) An Enucleated ovum b) Mature RBC c) A mature spermatozoan d) Hair root</p>
</blockquote>

<p>where the poster says that he thinks the answer may be a) or b) and explains his uncertainty (showing effort).</p>

<p>One could rephrase the question in the form:</p>

<blockquote>
  <p>Are there any cells in the human body that lack DNA? I can think of two but I'm not sure...</p>
</blockquote>

<p>PS</p>

<p>And if this does not appear to qualify as a question, then I am asking “Is there support for this suggestion and, if so, how can the policy be changed to implement it.” </p>
 3827: <p>As answers are supposed to be well researched and citing sources, a bad multiple choice question might still prompt an interesting, well structured answer explaining not only which is the right choice and why but also why the wrong choices are wrong. </p>

<p>Determining what could have been the 'pitfall' or 'trick' the instructor was trying to play can actually help the student and other people struggling with the underlying biology. For example with the example you were using there was a wonderful comment explaining, why the enucleated ovum is wrong and how someone could be mislead, effectively teaching people not to forget about mitochondrial DNA. </p>

<p>Re-formating the question with the "I can think of two..." option actually might prompt less valuable answers, as they will not explain, why the other two options given are wrong. </p>

<p>If we allow homework questions (of course with an attempt to answer), because they can lead to a nice collection of basic answers useful for people who might not generally contribute to the site but ended up here via google, I guess allowing multiple choice questions serves the same purpose.</p>

<p>If the question is clearly stated and all options are given, the problem is more in the quality and extend of answers (maybe only explaining what is right, not what is wrong) than in the question. You can quite often learn more if you are told what is wrong and why, then just memorising what is right.</p>
