Biochemists have created an artificial cell membrane that they hope to insert into artificial red blood cells for future dehydration and transportation into outer space. When scientists stain natural cell membranes with a heavy metal, they can view the membranes with an electron microscope. The heavy metal stains the polar hydrophilic heads of phospholipid membranes. If the artificial membranes resemble natural membranes, what area(s), when viewed under a microscope, would appear stained?
A
B
C
D

12) several teeth were found in an area of flat land covered with trees and plants. the teeth were examined by a paleontologist, and it was determined that the teeth came from a shark. they found many other shark teeth in this area. however, the people who discovered the teeth were puzzled, because there was no source of water near where the fossils were found. what is the paleontologist's best explanation for why the teeth were found in this area? a) sharks used to live on flat land. b) this area was once covered with salt water. c) this area was once covered with freshwater. d) someone buried the shark teeth deep in the ground.