Question

uestions 4 through 6 are based on the following information and graphic.
the processes that circulate nitrogen between the atmosphere, land, and organisms are
called the nitrogen cycle.

1. nitrogen - fixing bacteria are found both in the

soil and on the roots of legumes like peas
and beans. from where do these bacteria
get nitrogen?
a. ammonia and ammonium
b. the air and rainwater in the soil
c. animals and animal wastes
d. animal wastes and decaying plants

1. which of the following statements is a con-

clusion about the nitrogen cycle rather than a
detail in the diagram?
a. nitrogen oxides dissolve in rainwater.
b. nitrogen - fixing bacteria are found both
in the soil and on the roots of legumes.
c. the recycling of nitrogen through the
biosphere involves many complex
processes.
d. nitrite bacteria turn ammonia and
ammonium into nitrites.

1. to increase the nitrogen content of the soil,

many farmers spread synthetic fertilizers
containing nitrogen compounds. what might
an organic farmer, who does not use syn-
thetic fertilizers, do to improve the fertility of
the soil?
a. switch to crops requiring more potassium
b. compost with plant and animal wastes
c. plant more nonleguminous plants
d. switch to crops requiring more nitrogen

Explanation:

4.

The diagram shows that nitrogen - fixing bacteria fix nitrogen from the air and in rain. Option B is correct as it aligns with the nitrogen - fixing bacteria's source of nitrogen from the air and rainwater (nitrogen oxides dissolve in rain which is part of the nitrogen cycle for these bacteria). Options A (ammonia and ammonium are products in the cycle after nitrogen fixation), C (animals and animal wastes are part of decomposition but not the source for nitrogen - fixing bacteria's initial nitrogen), and D (animal wastes and decaying plants are for decomposers, not the direct source for nitrogen - fixing bacteria) are incorrect.

Options A, B, and D are details from the diagram (nitrogen oxides dissolving in rain, location of nitrogen - fixing bacteria, and nitrite bacteria's role). Option C is a conclusion about the nitrogen cycle as it generalizes the complexity of the recycling process involving many steps (fixation, assimilation, decomposition, etc.) shown in the diagram, rather than just stating a specific detail.

Option B is correct. Composting with plant and animal wastes (as shown in the diagram, decomposers break down these wastes) adds nitrogen - rich organic matter to the soil. Option A (switching to potassium - requiring crops doesn't add nitrogen), Option C (non - leguminous plants don't fix nitrogen like legumes with nitrogen - fixing bacteria), and Option D (switching to nitrogen - requiring crops would deplete soil nitrogen if not replenished properly without synthetic fertilizers) are incorrect.

Answer:

B. the air and rainwater in the soil

5.