The process by which a cell in culture acquires the ability to divide indefinitely, similar to the division of cancer cells ; or a change in genotype and phenotype due to the assimilation of external DNA by a cell . When the external DNA is from a member of a different species, transformation results in horizontal gene transfer:

The correct answer to fill in the blank is: transformation.

Explanation:

Transformation is a process that happens to a) cells when they change their phenotypes due to new genetic material, or b) cultured cells that keep having spontaneous phenotypic alterations due to the changes in their DNA.

Transformation can occur because spontaneously, or because of an infection with a transforming virus, gene transfection, exposure to chemical carcinogens or exposure to ionizing radiations.

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.