A researcher attempts to use a segment of ribosomal RNA as a molecular clock to calculate the date of the last common ancestor of two species. He finds that the two species diverged from a common ancestor 150 million years ago. These particular species have abundant fossil records that strongly suggest that these species diverged 100 million years ago. Which of the following answer choices best describes a reason for the discrepancy in the date of the last common ancestor of these species?

A. Ribosomal RNA is not a reliable molecular clock and should not be used for dating.
B. The neutral mutation rate used in calculating the last common ancestor date may not have been accurate.
C. It is highly likely that the two organisms did not share a common ancestor, so the results are invalid.
D. A large portion of the ribosomal RNA is not vital to survival, so it is not likely to be well preserved.

B

Explanation:

It is B because the mutation rate should not have been accurate if it showes that they diverged 150 million years ago. But the abundant fossil records show that it diverged 100 million years ago.

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water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.