How do fish obtain oxygen? a- oxygen diffuses across their skin. b- their body cells break down water molecules (h2o) and release the oxygen. c- they inhale oxygen at the surface of the water. d- they take in oxygen gas dissolved in the water through their gills.

Which of the following is an advantage of using embryonic stem cells in medical research? a. the use of embryonic stem cells is much less expensive than the use of adult stem cells. o b. no living tissue is damaged when scientists use embryonic stem cells. o c. embryonic stem cells are able to differentiate into a wider range of cells than adult stem cells. d. there is no controversy surrounding the use of embryonic stem cells.