Scientists have learned that when a pregnant woman smokes, one of the chemicals absorbed, nicotine, can narrow the diameter of her blood vessels that lead to the placenta. Explain why narrowing the diameter of these blood vessels can result in low birth weight babies.

Which statement best describes the nature of science? a. science discoveries using the latest technology are the most valuable. b. scientific theories and laws are based on beliefs and popular opinion. c. scientific ideas change over time as new information is discovered. d. science is superior to other fields such as art, philosophy, and music. i think its c

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point

In general, characteristics that an organism survive and reproduce become more common in a population over time. what mechanism of evolution cause this change?