The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, though some have three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that .

 it was known that, in the last common ancestor bilaterians used to have 4 Hox genes. Most extant cnidarians are having 2 Hox genes, though some of them have 3 Hox genes.

On the basis of these observations, some researchers have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that

the radial symmetry of extant cnidarians are actually the secondary derived, but not an ancestral trait .

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.

compost can be added to topsoil as a:

pesticide