Hi I really need some help my teacher told me to redo my last 3 questions

1.
Explain what it means for a section of DNA to be considered a molecular clock. Be sure to discuss the importance of neutral mutations in this measure of time.

Be sure to answer this question in paragraph form using complete sentences.

*this is what I said* Natural mutations aren't harmful nor beneficial but they are invisible to natural selection. but mutations can still spread into a population

*this is my teacher's feedback*Essay Feedback

good, but how does it relate to the molecular clock?

2.
Snakes and worms have no legs and share a similar tube-like body structure. Describe how you could determine how closely related these two types of organisms are.

Be sure to answer this question in paragraph form using complete sentences.
*this is what i said*
The snakes and worms most likely have a common ancestor that had tube-like bodies and no legs.

* This is what my teacher said* Nice start, but how do we know and what could we do to check out to know more.

3
A certain segment of DNA can be used as a molecular clock. Its rate of mutation is one mutation per 15 million years. Examine the DNA segments from two different species:

Species A: GTTGAGCTAGTATGGACC
Species B: GATAAGCTAGTAAGGTCA

Using this example, explain how this information can be used to determine how long ago these two species shared a common ancestor.

Be sure to answer this question in paragraph form using complete sentences.

* this is what I said *
while comparing species a and b together I see that 1 mutation occurs every 15 million years and I noticed that they had to share the same ancestor 75 million years ago.

Essay Feedback

* this is what he said* good try, but please take another look, I got 5 mutations, and what do you need to do with that info to find how long they shared a common ancestor?