29. How do living things contribute to the water cycle?
a. evaporation c. precipitation
b. condensation d. transpiration
30. Nutrients move through an ecosystem in
a. energy pyramids. c. biogeochemical cycles.
b. ecological pyramids. d. the water cycle.
31. If people take the subway instead of driving cars, which of the following will be reduced?
a. Water c. Oxygen
b. Carbon Dioxide d. All of the above
32. Which of the following statements is true?
A. The biogeochemical cycle does not involve biological organisms.
B. An element stays stuck in one place and does not travel around earth.
C. Humans are never part of a biogeochemical cycle.
D. Humans help recycle phosphorus when they eat plants.​