The process of aerobic respiration is a significant source of which of the following gases?

The process of aerobic respiration is a significant source of which of the following gases?
 
  A) carbon dioxide
  B) ammonia
  C) oxygen
  D) nitrogen
  E) methane

Question 2

Recent research with annual crops such as wheat, sunflower and sorghum in the Great Plains region suggests that, compared to continuous cropping, soil quality, crop productivity and farm profitability are likely to be greater when crops are grown in a field only every second year with the soil keep free of weeds in the non-crop year by repeated cultivation of herbicide application.
 
  Indicate whether the statement is true or false

Question 3

The bulk of gaseous interchange in soils takes place by ________.
 
  A) dissolution in water
  B) mass flow
  C) respiration
  D) partial pressure of N2
  E) diffusion

Question 4

Soil A has a redox potential of 400 mV, soil B -200 mV. Of the two soils, Soil A is more apt to be characterized by an abundance of ________.
 
  A) Fe2+ ions
  B) H+ ions
  C) S2- ions
  D) Mn2+ ions
  E) molecular oxygen