Which of the following best describes why deforestation increases the risk of floods in an area? a)trees catch leaves and retain rain water. b)trees block the free flow of water. c)deforestation increases precipitation. d)tree roots improve soil water retention.

Which statement is true for bacteria a. bacteria have complex internal structures b. all bacteria are spiral in shape c. all bacteria cause disease in animals d. bacteria break down some foods

Why do mountaineers become breathless as they reach high altitudes

An adult inhales about 6.0×10−4 m3 of fresh air during a breath. only 20% of fresh air is oxygen. assume the pressure in the lungs is 1.0×105 paand the air is at a temperature of 300 k. how many oxygen molecules are in each breath? a. 1.4x10^23 b. 2.9x10^21 c. 4.9x10^-4 d. 2.9 x10^25