Nitrogen-based fertilizers break down into nitrates. when the nitrates enter the substrate, they are converted into nitrogen gas through which process?

The right answer is Denitrification.

Denitrification is a microbial process of alternative respiration. This biological phenomenon is operated by specific bacteria, satisfying their need for oxygen in hypoxic or anoxic soil, by a deoxygenation of nitrate ions. This phenomenon occurs in the soil, but not exclusively: it is also at work in certain sediments, in aquifers (to a certain extent and under certain conditions), in decaying organic matter (eg dead wood), or in the digestive system.

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

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