Question

Which of the following best describes an example of how genetic codes of organisms have been used to help hierarchically classify living things?

Answer 1

The common nucleic acid sequences of polar bears and black bears can be deduced from their classification in the same genus, Ursus.

Viruses contain DNA which is used to classify which hosts they will infect into a Linnaean taxonomy of viruses.

Since kangaroos and opossums both have developed pouches to carry their young, it proves that they share DNA sequences and belong to the same species.

Even though Eubacteria and Archaeabacteria look similar, differences in their ribosomal RNA led to their classification into different domains.

Answer 2

Again, process of elimination will really, really help you with these multiple choice questions. :) Do any of the options strike you as being likely? Do any of them strike you as being unlikely?

Answer 3

im just not sure. Im taking a pretest, so the answers that I get wrong won't matter based on my score.

Answer 4

Cool. The idea behind this question is that if two different species have really similar genetic codes, then they are closely related. If they have really different genetic codes, then they are really distantly related. And one of your four options really emphasizes this....

Answer 5

but all of the answer choices are very similar. Which one should I chose?

Answer 6

OK, let's go through the possible answers one by one.

The first one says that if you look at two species that you know are closely related, you can tell what exact similarities and differences they have in their genetic code.

I don't like it. First of all, it requires that you assume the species are closely related, which is the opposite of what the question is asking you. And second of all, there is no way of looking at two closely related organisms, without knowing the genetic codes of either, and using similarities in how they look to predict how the genetic codes are different...

What is your opinion of the second option?

Answer 7

I guess I could eliminate the second option because they say something about virisus.

Answer 8

I agree.

Similarly, I don't like the third. It says that if two organisms look similar, they must be closely related. There are many cases where very distantly related organisms share a common environment and are subject to the same evolutionary pressures, so they start to look the same.

Which leaves the fourth and final option standing. :)

Answer 9

i understand.

Answer 10

its D.

Answer 11

Cool. Honestly, learning to us process of elimination as a test taking strategy is probably more important than learning the actual science. Even if you don't know what it is, if you can eliminate a couple of the options - like the one about viruses - and then guess, it makes the odds that you will guess correctly much better.

Thanks for your patience working through the problem. :)

Answer 12

Thanks. :D