An amino acids between the two species, there are twenty positions along the sixty amino acids sequence that are identical between the aphid and the bacterium Pantoea. A computer can be used to compare these quences from the rest of the species to the aphid sequence.
Answer:
D. They define geological periods because scientists use them as reference points for tracking the history of the earth.
Explanation:
Catastrophic events related to changes in geological timeline are very useful in defining geological periods.
These events have very significant appearance in the geological record and can be used to determine the history of the earth.
The catastrophic events usually culminates into extinction cycles or termination of some organisms from the earth surface.
Geologists use these events that are often wide spread to delineate geological periods.
Microbes that live stably in and on the human body are called, <u>human </u><u>microbiome.</u>
<span>C) The age of a fossil can be determined by examining the rock strata in which the fossil is found.
[ Age can be determine, that's why Scientists can predict an event on Geographical scale, so evolution could be studied ]
Hope this helps!</span>
