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my teacher assigned these worksheet questions, they are ungraded, but he said something might come up on the test really similar to this so I really want to get all of them right. I am pretty confident with all of them except for two, In the layer below a mass extinction that devastated the region, the paleontologist observed that shells of species A was present in small numbers over a widespread area whereas species B was abundant and found in a few restricted areas. Which of the following predictions about the fossil record in the layer above the mass extinction is the MOST likely to be supported by further excavations?

A.  

Species A survived because of its widespread range including some areas that were not as affected by mass extinction.

B.  

Species A survived because the low number of individuals meant that there was less competition for resources.

C.  

Species B survived because it was the more abundant and more individuals survived.

D.  

Species B survived because the population was concentrated in a few areas and had a higher chance of survival.

and

A scientist analyzes the vision receptor molecule in invertebrates and vertebrates. The results show that the genes for opsin, the protein part of the photoreceptor, share strong homology in the regions that code for domains involved in light response. Which of the following conclusions is the MOST likely?

A.  

The receptor molecules will be structurally different but respond to the same light cues.

B.  

The receptor molecule will be similar in invertebrates and vertebrates because of convergent evolution.

C.  

The receptor molecules will be different because invertebrates and vertebrates perceive visual cues in different environments.

D.  

The receptor molecules will be similar in invertebrates and vertebrates because they appeared early in evolution.

For the first one, I reasoned that it was most likely A, however, D caught my attention and now I am seriously doubting myself on it. This is due to the fact that the wide range of an organism might lend itself to higher survival, as some regions might better be protected or missed by harm, however, it could just as likely be D, in my opinion, as more animals might lend to quicker recuperation in any instance. For the second, I am pretty confident it is A, as homology means they come from the same source but may evolve to differ, but again, D is pretty tempting as it may be simply as it was an element that appeared early on and thus is present in both. I am only an undergrad premed, so not too savvy yet, but any help would be great.

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closed as too broad by Remi.b, David, WYSIWYG, iayork, kmm Apr 9 at 3:37

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Homework questions are off-topic on Biology unless you have shown your attempt at an answer. For more information see our homework policy. See also biology.meta.stackexchange.com/questions/3377/… Please edit your question to have an informative title, limit your question to a single specific question, and explain the reasoning behind your answer attempts rather than just your guesses and confidence. It would also be better to phrase your question as a conceptual question rather than multiple choice. $\endgroup$ – Bryan Krause Apr 6 at 0:30
  • $\begingroup$ Thank you for the reply, I explained my reasoning further and updated my title. But I didn't see anything about asking one single question in your links, thank you very much for them by the way, I am not being rude! I will totally cut it down if necessary $\endgroup$ – Nancy Apr 6 at 0:43
  • $\begingroup$ We really don't answer homework questions, as @BryanKrause stated very politely. Our goal, ado, is not to simply be an answer site, but rather a site that promotes self-learning with some expert help along the way :) I was about to close vote, but it's better after the edit. $\endgroup$ – anongoodnurse Apr 6 at 0:47
  • $\begingroup$ Thanks for taking the time to reply :) I totally understand that, I can add more to my question, I really want to completely grasp the topic, or I can rewrite it completely if you guys think that would be best. I would ask my prof but I wont be able to until a little while. $\endgroup$ – Nancy Apr 6 at 0:53
  • $\begingroup$ Your two questions are unrelated (other than the fact that both of them are parts of your homework). Therefore I am voting to close your question as broad. Your edit is good enough to make the question on-topic. I recommend that you ask two separate questions and rephrase your question titles accordingly. $\endgroup$ – WYSIWYG Apr 8 at 14:08
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The first question is poorly designed the only things with a high chance of surviving mass extinctions are organisms that occur in large numbers over a wide range of environments, without more detail neither A nor B would have a strong preference for survival compared to the other. Mass extinctions are too unpredictable, neither by itself gives you a large advantage.

It really depends on how they define terms the only organisms that occur over a truly wide range of environments that is both marine and terrestrial ones are tiny and thus have huge population numbers. the more localized the measure of widespread the less being widespread matters. for instance Ammonites occured in every marine environment in large numbers (so a wide range of local environments) but were completely wiped out because the ocean PH changed which hits every portion of the ocean equally.

The best you might be able to say is A might have a slight advantage because it is more of a generalists as it occurs in more environments but that use of the term "within a region" means it does not help much.

The second question is easy, if the genes are sequentially similar it is due to a common ancestor. since the sequence is part of the functional component then the ancestor likely used it for the same function, so D would be your best answer.

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