Bio Test

Biogeochemical Cycles

Suppose nitrification slows down, but nitrogen fixation continues. Which form of nitrogen would you expect to build up, and which would become less available, assuming everything else stays the same?

Ammonium would tend to build up, and nitrate would become less available because less ammonium is being converted into nitrate.

How are evaporation and transpiration similar? How does replacing a forest with pavement affect transpiration and surface runoff?

Both add water vapor to the atmosphere. Evaporation occurs at surfaces such as lakes and soil. Transpiration releases water vapor from plants. Replacing trees with pavement reduces transpiration and generally increases surface runoff.

How do weathering and decomposition both supply phosphate to the soil? Where does the phosphorus come from in each case?

Weathering releases phosphate from rock. Decomposition recycles phosphorus from dead organisms or waste, making phosphate available again.

Compare how carbon and phosphorus enter a plant. What form does each center in, and what part of the plant takes it in?

Plants take in CO₂ through stomata, mainly in their leaves, and absorb dissolved phosphate through their roots.

If decomposers became much less active, what would happen to the carbon and phosphorus in dead leaves? Where would each normally go as the leaves break down?

Both would stay in the dead leaves longer. As leaves decompose, some carbon normally returns to the air as CO₂, and phosphorus is recycled into the soil as phosphate.