With order of magnitude question? the rate of motion of the earth at its equator is about 1,038 mi/h because of its rotation. from this information, estimate the earth's circumference using an order-of-magnitude estimate. question 21 options: 2,000 mi 20,000 mi 200,000 mi 2,000,000 mi

The rotation of Earth is equivalent to one day which is comprised of 24 hours. To determine the number of miles in Earth's circumference, one simply have to multiply the given rate by the appropriate conversion factor and dimensional analysis. This is shown below.
 
                  C = (1038 mi/h)(24 h/1 day)
                   C = 24,912 miles

From the given choices, the nearest value would have to be 20,000 mile. The answer is the second choice. 

How is it possible that phylogenies based on sequences from nuclear genomes and organellar genomes (i.e., chloroplasts and mitochondria) from the same group of species yield phylogenetic trees with different branching orders?   answer :   the genome of the endosymbiont is more closely related to members of the group in which it originally evolved, while the nuclear genome of the engulfing organism has its own evolutionary trajectory.