Question

What should be true of a molecule being used as a molecular clock?
a) It has a consistent rate of neutral mutations from generation to generation.
b) It is a rare molecule that is not found in many living species that might be compared.
c) Its mutations always affect the phenotype, making it easier to observe the changes.
d) It serves an unnecessary function, making it less likely to be preserved over time.

Answer 1

It really helps if you tell us your tentative answer to the question, or if you tell us what part of the problem you don't understand....

Answer 2

i think is c. I'm not sure i dont really understand this question

Answer 3

I think it's A.

It's not C because by looking just at the outside of the organism, it's phenotype, it would be impossible to know exactly what mutations have occurred in what genes, which is what you need to know in order to compare DNA sequences of the same gene between different species.

Answer 4

Clear?

Answer 5

YES thank you !

Answer 6

I am going to say A as well. Molecular clock infers a rate which A addresses. Also, a classic example of a molecular clock concept uses cytochrome C in which the changes are neutral mutations - too much change and this vital protein does not work. This would not be an "easily observable phenotype" unless someone considers protein sequencing an easy endeavor. Also, mitochondrial DNA is used to trace human ancestry because of its a higher mutation rate than nuclear DNA. Of course, consistent is an interesting word here. If there is punctuated equilibrium at play, it may not be a consistent rate. However, a silent mutation can be found by DNA/protein sequencing so I would not think there absolutely has to be a phenotype change to be seen. Go with A.