What explains the presence in living humans of DNA sections which are identical to DNA found in Neanderthals who lived 40 000 years ago?

It can be explained by hybridization among human and neanderthal ancestral populations.

Explanation:

Next-generation sequencing (NGS) technologies coupled with bioinformatics tools have enabled to confirm admixture between Neanderthals and humans. The technique to identify admixture events consists in discovering nucleotide regions from neanderthal genomes that could be inserted in human genomes, thereby the observed sequence homology must be statistically significant (e-value). This emergent research field is known as paleogenomics.

answer: all : )

explanation:

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.