Examining a dolphin highlights its evolutionary history. Early in dolphin development, both fore and hind limb buds form. While the forelimb buds continue to develop into , the hind limb buds . The that are normally active in the hind limb buds of four-limbed animals are . A change leading to the silencing of a trait during development may have been an important milestone in cetacean evolution.

Two students are working together on an experiment that measures the effect of different liquid fertilizers on the thickness of plants’ stems. which is most likely to result in the greatest amount of error in their scientific experiment? a.one student measures the plant stem widths by using calipers. the other student measures the widths of the same plant stems again by using a different pair of calipers. b.one student measures the plant stem widths by using calipers. the other student types the measurements as they are taken into a computer spreadsheet. c.one student weighs liquids for the experiment by using a calibrated scale. the other student weighs liquids for the experiment by using a different calibrated scale.