How does oxygen move from the respiratory system to the circulatory system? a. by pumping through the heart b. by circulating in an artery c. by moving across a synapse d. by diffusion across a capillary wall

Which plant has a visible leaf modification that will it conserve water in extremely dry environments?

What have we learned from fossil evidence about evolution? a) it is an abrupt change. b)the process is observable. c) it takes place during one lifetime only. d)the most complex traits are always selected.

The transport tubes for food coming down the plants are called?