Which of the following is not a biogenous sediment?
a. manganese nodules
b. calcareous ooze
c. siliceous ooze
d. phosphate-rich material
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A. manganese nodules.

Biogenous sediment is sediment that is obtained from materials produced by marine plants or animals such as teeth, bones, shells, coral reefs and others. It comes from the hard parts of these dead animals and plants. Calcium and silica are the main biogenous sediments. For example, calcium carbonate is chief ingredient of coral reef. Teeth, bones and shells are made up of calcium. Silica is the outer cell wall of diatoms and protozoa and they are also useful for making shells of marine organisms. Phosphorous is also the component of organic matter deposited by the dead organisms.

Therefore, manganese nodules is not the part of biogenic sediment.

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.