Spring scale A is attached to the floor and a rope runs vertically upward, loops over an ideal pulley, and runs down on the other side to a 281-N weight. Scale B is attached to the ceiling and the pulley is hung below it. Ignore the weights of the rope, pulley, and scales.

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.