If more women have the trait than men, this rules out sex-linked recessive. A sex-linked dominant trait would be more commonly seen in women than in men (75% vs 50% assuming two alleles each with an allele freq of 0.5) but the question said the trait is predominantly in women indicating that few men have it. This suggests to me that there is a complex inheritance pattern involved. One possibility is co-dominance or incomplete dominance, in which two copies of the X must be inherited for a particular phenotype to appear. However, it is hard to see how this would work for disease phenotype. Also, this probably wouldn't work because of X-inactivation. Perhaps a male specific lethal? Alternatively, the disease is more likely to appear in women because of interactions with other genes. In this case the disease gene could be on any chromosome.
I think this is an interesting thought question and could work well as a short answer/essay question for advanced students but not as a MC question.
If there is simply a mistake in the question (should be more men have the trait), I would say that the question is weak because many students will be able to answer from memorized information and still not understand why. Perhaps give data on a sex-lined trait and have the students analyze to determine an answer? |a|b|a|a|A: This question deals more with how "mutation" is defined rather than asking students "to able to compare different types of mutations and describe how each can affect genes, mRNAs, and proteins." B: no scientific info provided. C: Yes though I would change the last sentence to "Is this change a mutation?" |c|a|a|b|I'm not sure if this addresses processes that affect allele frequency rather than why/how the allele appeared. |b|a|a|a|Good question. |d|c|a|b|The information provided with the question deals with translation. However, the question is asking about RNA production - transcription. These changes described in the possible answers would affect protein production, not RNA production. If the question was meant to ask about protein production, answer b or c could be correct. B would introduce a premature stop. C would introduce a new start codon which could potentially be used to start translation of a new peptide. Also, why include the DNA sequence if it is not needed. The DNA sequence shown is not the complement of the RNA shown. Just show the RNA sequence unless you want the students to determine what the RNA should be from its DNA complement. I would consider this to be what my students refer to as a "trick" question. The question asks one thing but the information provided addresses something else. |c|a|a|a|This would be a challenging question as the mutation does not directly result in a shorter peptide, but rather indirectly by introducing a stop codon downstream as a result of a frame-shift|d|a|a|a||d|a|a|a||e|a|a|a||b|a|a|a||c|a|a|b|Perhaps include offspring from the affected daughter from the F-1 generation. |b|a|a|a||c|a|a|a||c|a|a|a||a|a|a|a||d|a|a|a||c|a|a|a||b|a|a|a||c|a|a|b|Identifying the mutation in affected individuals would be best but could be confounded if the trait is recessive. Heterozygotes would have the allele but not the disease. Good students might pick up on this. Perhaps have test for the presence or absence of the dominant (?) normal allele? |c|c|a|a|Good question but doesn't address the learning goal stated: "Students should be able to justify the value of studying genetics in organisms other than humans."|b|a|a|a||e|b|b|b|Good idea for a question in that it address a complicated issue: how do you define phenotype? As the physical manifestation of a trait or at the level of protein production and activity? . For a classic mendelian trait, you would expect to see increased function in the protein. However, the answer would depend on the trait being examined and how the gene is responsible for expressing this trait. A new function, though unlikely, could cause a dominant trait. Also, the question doesn't completely rule out incomplete- or co-dominance. Indeed, at the protein level, increased function of a protein could be viewed as incomplete dominance when average protein function is compared between homo- and heterozygotes. Consider flower color in mendel's peas (purple/white) and in snapdragons (Red/white/pink). Similar mechanism at the protein level but different physical manifestation at the organismal level. |c|a|a|a||e|b|a|b|Not enough information is provided to draw an accurate conclusion. It is possible that chromosomal fusions occurred that reduced the total number of chromosomes in the new species. However, it is also perfectly possible that the overall phenotype displayed by both species is selectively advantageous and that they are not closely related. |a|a|a|a|| 18:36:13|04-14-2008|428|Steven Wasserman|UCSD|c|c|a|a||a|c|a|a|I think this focuses on semantics, not science. Would it be a mutation if it were not replicated? Do I care if students can answer such questions?|c|c|a|a|What does the fact that mutations are random have to do with "processes that can influence the frequency of alleles?"|c|c|a|a|The problem is whether one wants to consider intragenic complementation. I dislike the wording for that reason.|d|c|a|a|This is a classic trick question. I am stopping here, because I have not found one of the first five questions useful.|not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered|| 18:52:08|04-14-2008|13608|Jiro Yasuhara|University of California, Berkeley|c|b|a|b|My first impression was that this question was unnecessarily tricky in a non-productive way. But on second thought, it may not be so bad a question. They will first jump to X chromosome because of the sex-specificity, but hopefully they will then realize it can not be explained by simple Mendelian law. I feel that students who get it will get it, but those who don't will be left confused and won't gain much even after they are told the correct answer. |a|a|a|a|Here is something else that could be taught in more advanced courses: even 'synonymous' mutations are not always neutral and could have unpredictable but potentially grave consequences on gene expression. 1. There is preferred codon usage unique to every organism. An unfavored codon, even if it is synonymous, could substantially slow down or even halt translation at the ribosome. 2. Exons not only encode protein sequence but also contain splicing signals. Mutations in the coding sequence, synonymous or not, could result in aberrant splicing and thus dramatically alter the protein product. |c|a|a|a||b|a|b|b|Strictly speaking, in rare cases, situations like a) are known to exist. It's called interallelic complementation. (So students who answered c) should also get credit) Aside from this caveat, complementation is such an important concept and I thought this was a good question. Minor criticisms: I thought the word "offspring" could mean all subsequent generations including F2, F3... You should be more specific. Also, I thought you might need to specify that both "mutant lines" are homozygous for the respective mutations.|d|a|a|not_answered||c|a|a|a||d|a|a|a|This is a good question that makes you think. I'm not sure if it's appropriate to call colorblindness a disease. It might offend them! |d|a|a|a|An interesting deviation on this topic is the individual-to-individual transmission of the tumor in Tasmanian Devils. Another topic for an advanced genetics course.|e|a|a|a||b|c|b|c|This question really doesn't make sense. If this is talking about alleles at single nucleotide position, then the correct answer is b). Or is this talking about polymorphisms in four different positions? Then you can actually generate many more than four "variants" of the gene by recombining different "alleles". |c|a|a|a||b|a|a|a||c|a|a|a||c|a|a|b|I would say "carrier for the mutation" not "carrier for the disease".|a|a|a|a||d|a|a|a||c|a|a|a||b|b|a|a|This is another question that's kind of tricky but not very rewarding.|c|b|a|a|The most definitive choice is still not definitive enough to me.|c|b|b|b|Nucleotide sequence similarity and amino acid sequence similarity are not simply comparable. I don't think this is particularly a good question. |b|a|a|b|recombination 'with' each other, or 'between' each other?|e|a|a|a||c|b|a|b|The question is too involved for addressing a simple concept. Reading about the dashed line etc. will just confuse students and they will get little reward for their investment. |e|a|a|a||a|a|a|a|| 18:52:52|04-14-2008|976|Dominique Bergmann|Stanford University|c|a|a|a||a|b|a|b|This is a bit of a "definition" question. I might re-order the answers to make students read through them all before deciding|c|b|a|a|I'm not certain that this addresses how allelic frequencies are established.|b|a|a|a||d|a|a|a|I got this one wrong by reading too quickly--having the sedond question immediately follow it caused me to go back to this one and revise my answer|c|a|a|a||d|a|a|b|I liked this question a lot. But shouldn't mutant gene be mutant allele?|d|a|a|a||e|a|a|a||b|a|a|a||c|a|a|a||b|a|a|a||b|a|a|a||b|a|a|a||a|a|a|a||d|a|a|b|choice c is something that my students would try to argue was correct (though it isn't)|c|a|a|a||b|b|a|a|I feel like there should be a follow up question here to reinforce the idea that Dom alleles don't alway correlate with the same type of phenotype.|c|a|a|a||c|a|a|a||b|a|a|a||e|a|a|a||c|a|a|b|"under what conditions" is a odd phrase here. it makes it sound conditional.|e|a|a|a||a|a|a|a|| 08:10:36|04-16-2008| 12:04:06|04-17-2008|2846|Rob Brooker|University of Minnesota|not_answered|a|a|a||a|a|a|b|The fourth word should be base not nucleotide.|c|b|a|a|The question is more about the origin of mutation rather that allele frequencies.|b|b|a|b|Two things. First, I'm assuming that the goal is for students to get the concept of complementation, which is very high level for a pre-test. Second, the term "line" may be so unfamiliar to the students that they won't understand the question. |d|b|a|a|One of the substitutions should have created a stop codon, which still would not affect the length of the mRNA. This is a missed opportunity to probe students understanding.|c|a|a|a||d|a|a|a||d|a|a|a||e|a|a|a|Very good question! I'm stealing it.|b|a|b|a|The number of variants you refer to are probably those that cause cancer. I'm sure there are lots more than 4 in the human population. SNPs are very common in a gene of this size.|c|a|a|a||b|a|a|a||c|a|a|a||c|a|a|a||a|a|a|b|I think it's really bad to call this the "breast cancer gene". The normal function of the gene isn't to cause breast cancer. I would call it " a gene named BRCA1 that is associated with breast cancer," or something to that effect. |d|a|a|a||c|a|a|a||b|a|a|a||c|a|a|a||a|b|a|a|I'm assuming that DNA is the correct answer because intron sequences and wobble bases are more variable than amino acid sequences. I guess I'm thinking that students will assume that mRNA and DNA are or could be the same since you haven't said the gene contains introns. Maybe you should add that idea to the question. Also, I think the learning goal is more about gene evolution. |b|c|a|c|As a pre-test, this question has a lot of problems. First, you haven't described the testcross. Second, I don't think students will know what "recombinants" are. |e|a|a|a||c|a|a|a|I think this is an awefully high level question for a pre-test.|e|a|a|a||a|a|a|a|Good question....especially for a pre-test.| 14:48:31|04-17-2008|18|mindy test||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered|| 00:16:21|04-20-2008|5714|Susan Strome|UCSC|c|b|not_answered|a|I think this is meant to probe if they know that an inherited disease that primarily affects MEN is more likely to be on the X. If that is the goal, it seems like a round-about way to ask the question.|a|b|b|b|It doesn't seem like this tests your learning goal. Were you after c or d? If so, then I don't think those statements are accurate.|c|a|a|a||not_answered|b|a|c|The answer I would like most is "probably have mutations in different genes" or "probably have mutations in different genes, but more info is needed to be certain" (certain that it is not intragenic complementation).|d|a|a|a||c|a|a|a||d|a|a|a||d|a|a|b|I wonder if genetic predispositions will confuse students. If the man was genetically m/+ (as in brca1/+ for breast cancer or Rb/+ for retinoblastoma) and a mutation arose in his other allele in 1 cell to cause cancer, then he could pass on the m allele to his children.|e|a|a|a|Good question, and I bet lots of students miss it.|b|a|a|a||c|a|a|a|I like it|b|b|a|b||c|a|a|a||c|a|a|a|Good question|a|a|a|a||d|a|a|a|This doesn't strike me as being in the top tier of concepts students should know.|c|a|a|a|Good question|b|a|a|a|Good question|c|a|a|a||c|a|a|a||b|a|a|a||e|b|a|b||c|a|a|a||e|b|a|b||a|a|a|a|| 11:13:08|04-21-2008|1204|Andrew Singson|Rutgers University|c|a|a|a|There are several questions that have the open ended solution. One drawback to this type of question, especially if the answer is C, is that it leaves me a little uneasy.|a|a|a|a|My response to all of these questions is that they do test the learning goal, the information is scientifically accurate and the question is written clearly enough for me to (think I) understand what is being asked. All of the questions in this assessment are very good.|c|a|a|a||b|a|a|a||d|a|a|a||c|a|a|a||d|a|a|a||d|a|a|a||e|a|a|a||b|a|a|a||c|a|a|a||b|a|a|a|I note that in many questions a partial understanding of a concept can be dangerous.|c|a|a|a||b|a|a|a||a|a|a|a||d|a|a|a||c|a|a|a||b|a|a|a||c|a|a|a||c|a|a|a||b|a|a|a||e|a|a|a||c|a|a|a||e|a|a|a||a|a|a|a|| 16:53:07|04-23-2008|3821|Kim McClure|UCSF|c|a|a|a||a|a|a|a||c|not_answered|not_answered|not_answered||c|a|a|a||d|a|a|a||c|a|a|a|Difficult to look back and forth at question and data presented above in previous question.|d|a|a|a||d|a|a|a||e|a|a|a||b|a|a|a||a|a|a|a||b|a|a|a||d|a|a|a||b|a|a|a||a|a|a|a||d|a|a|a||c|a|a|a||c|a|a|a||c|a|a|a||c|a|a|a||not_answered|not_answered|not_answered|not_answered||e|a|a|a||b|a|a|a||a|a|a|a||c|a|a|a|| 12:24:24|04-29-2008|7|||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered||not_answered|not_answered|not_answered|not_answered|| 13:24:39|04-29-2008|3114|Phil Meneely|Haverford College|c|b|a|a|It does not test modes of inheritance but instead tests knowledge of modifications of the phenotype. A disease that affects women much more than men is most likely to be sex-limited or sex-influenced, and could be either X-linked or autosomal. |a|b|a|b|In a strict sense, a change in the nucleotide sequence is a mutation so I guess this is correct but I am not wild about this method of testing the concept.|c|a|b|a|Other than the fact that it seems unlikely that a single mutation would affect tooth length and thus nutrition without affecting any other aspect of fitness, this seems OK. |b|a|a|a|Good example of a complementation test. |d|a|a|b|I think that a question about a mutation at a splice acceptor or a splice donor site might test this better. |c|a|a|a||d|a|a|a||d|a|a|a||e|a|a|a||b|a|a|a||c|a|a|a||b|a|a|a||c|a|a|a||c|a|a|a||a|a|a|a||d|a|a|a||c|a|a|a||b|a|a|a||c|a|a|a||c|a|a|a||b|a|a|a||e|b|a|b|I am not sure this really addresses the learning goal since any of the ansewrs could be true. It does not really test what they know about why a mutation is dominant. |c|b|a|b|I think this could have been asked quantitatively just as easily, but this is OK. |e|b|a|b|Again, when the answer is is "all of the above" or "none of the above", you are not really asking the student to distinguish between possible answers. |not_answered|a|a|a|Assuming that the crossovers occurred distally to the gene in each case or that these are being tested before crossovers have occurred. | 01:19:23|05-16-2008|1221|Ryan Joseph|University of California, San Francisco|a|a|a|a||a|a|a|a|Question does get the point across that any change in DNA sequence is a mutation, regardless of the phenotypic effect.|c|a|a|a|Good combination question to demonstrate students' knowledge that beneficial mutations are rare (and generally originate from one individual), and to make sure they do not mix the selection process with Lamarkian-style logic.|c|a|a|a|This question might be a little difficult if not much time was spent in class discussing intragenic complementation or intergenic non-complementation.|b|a|a|a|Nice way to test lots of concepts in one question.|c|a|a|a|I like this question--it effectively tests if they really understand the concept of frameshift mutations.|d|a|b|b|The question does not rule out the possibility that both parents could be carriers for an autosomal recessive color blind gene. Maybe the question should be changed slightly to say: "which of the following descriptions provide the best possible explanation for how the daughter inherited..."|d|b|b|c|The question does not account for the possibility that the gene causing the skin cancer is an oncogene or allele with a tendency to be easily mutated and cause cancer. Having such an oncogene/susceptible allele means the kids would inherit a predisposition to receive cancer from their father, even though the critical mutation itself occurs in somatic tissue (much like in Retinoblastoma). Maybe the question can be clarified with a phrase like: "the mutation responsible occurred in a gene in a single skin cell that has not previously been associated with cancer development."|e|a|a|a|Good test of the concept that all cells contain all genes.|b|a|a|b|Could add a "assuming no duplication events have occurred" as a stipulation to cut down on objections from the students.|c|a|a|a|Difficult but good pedigree question.|b|a|a|a||c|a|a|a||c|a|a|a|Although some students might find it difficult, this is a very important question to ask with regard to probabilities in genetics.|a|a|a|a||d|a|a|a|Good way to test if they know that human X-inactivation is random.|c|a|a|a||b|a|a|a|Good way to make sure students understand the concept of dominance and recessiveness, when true-breeding strains are crossed to generate heterozygotes.|c|a|a|a||d|b|a|b|The question might cause some confusion because it doesn't clarify if introns are included when comparing DNA sequences, which would likely result in DNA sequences being less similar than mRNA or protein sequences.|b|a|a|a|Use of the word probably in the question above is good/important.|e|a|a|a||c|a|a|a||a|a|a|a|Good question to test if they "unlearned" a lot of common misconceptions and assumptions about genomes.|a|a|a|a||