If you wanted to determine how closely related two modern day organisms are....?

Question

...which of the following would be good strategies?



A. Comparing embryo morphology
B. Doing radioactive dating
C. Looking for structural and genetic similarities
D. Comparing their fossil records

Answer 1

All of them.

A - Tells you many things, such as at what stage of development a certain folding of a layer of cells takes place. For example, this is what tells us that jellies and anemone's are very closely related (the cnidarians).
B and D are helpful when done *together*. The fossil development of both species, when compared to the time that it is happening, can tell us when the two branched off from each other.
C is the primary way to tell ... we compare details of physical structure, as well as molecule-by-molecule similarities and difference in the DNA. The molecular (DNA) information is so powerful that it can tell you not only that two organisms branched from the same ancestor, but it can tell you approxmately how long ago this occurred (in the thousands or millions of years).

So if you had to pick one "best" answer, it would be C ... but I would say that all of the above would be correct as well.

Answer 2

A is nice. Gives a lot of info about where creatures come from.
B is nonsense.
C Sure! A is just looking for similarities in the embroynic state, this is more comprehensive.
D Yep, if you know where an animal came from you can say something about common ancestors.

Answer 3

The answer would be C. By comparing structures, you are doing comparative anatomy. Genetic similarities include great similarities in amino acid sequence or DNA sequence.

Answer 4

particularly C - searching for structural (i.e. on a protein aspect) and genetic (i.e. gene sequence and shared homology) similarities. the second one section is fairly accomplished by technique of technique of genomic sequencing (noticeably now that the human genome has been completely sequenced). the first bit is more suitable efficient complicated, because the "proteome" of an organism isn't continually suitable conventional.