Chapter 17, Problem 17A

Summary Introduction

Introduction:

A molecular clock is a model that is used by systematics to compare DNA sequences from two different species to estimate how long the species have been evolving since they diverged from a common ancestor. Biologists use molecular clocks to compare DNA sequences or amino acid sequences of genes that are shared by different species.

Answer to Problem 17A

Correct answer:

The correct answer is option D. the time of divergence

Explanation of Solution

Explanation/justification for the correct answer:

Option D. the time of divergence − The rate of mutation in a molecular clock is affected by many factors such as type of mutation, location of gene within the genome, the type of protein that the mutation affects and the population in which mutation occurs. It is not affected by time of divergence of species.

Hence this is the correct option.

Explanation for incorrect answer:

Option A. type of mutation − The rate of mutation in a molecular clock is affected by type of mutation. It is not affected by time of divergence of species. Hence this is not the correct option.

Option B. location of gene in genome- The rate of mutation in a molecular clock is affected by location of gene in genome. It is not affected by time of divergence of species. Hence this is not the correct option.

Option C. the protein affected − The rate of mutation in a molecular clock is affected by the type of protein that the mutation affects. It is not affected by time of divergence of species. Hence this is not the correct option.