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Study the cycle shown below and select the option which gives correct words for all the four blanks A, B, C and D.
A
A – Nitrification, B – Ammonification, C – Animals, D – Plants
B
A – Denitrification, B – Ammonification, C – Plants, D – Animals
C
A – Nitrification, B – Denitrification, C – Animals, D – Plants
D
A – Denitrification, B – Nitrification, C – Plants, D – Animals
Detailed Solution
The figure is the nitrogen cycle, showing atmospheric $N_2$, the soil nitrogen pool ($NH_3 \rightarrow NO_2^- \rightarrow NO_3^-$) and the biomass.
A is the arrow from nitrate in the soil back to atmospheric $N_2$: reduction of nitrate to nitrogen by bacteria such as $Pseudomonas$ and $Thiobacillus$ is denitrification.
B is the arrow from decaying biomass to $NH_3$: decomposition of the organic nitrogen of dead plants and animals into ammonia is ammonification.
C receives nitrate/ammonia from the soil by 'uptake': these are the plants.
D is the group that obtains its nitrogen from plants and returns it to the decaying biomass: the animals.
Hence A – denitrification, B – ammonification, C – plants, D – animals.
A is the arrow from nitrate in the soil back to atmospheric $N_2$: reduction of nitrate to nitrogen by bacteria such as $Pseudomonas$ and $Thiobacillus$ is denitrification.
B is the arrow from decaying biomass to $NH_3$: decomposition of the organic nitrogen of dead plants and animals into ammonia is ammonification.
C receives nitrate/ammonia from the soil by 'uptake': these are the plants.
D is the group that obtains its nitrogen from plants and returns it to the decaying biomass: the animals.
Hence A – denitrification, B – ammonification, C – plants, D – animals.