| A | B |
|---|
| nucleolus | a small dense region within the nucleus where ribosomes are assembled |
| nuclear membrane | a thick barrier that regulates materials that can enter and leave the nucleus |
| nondisjunction | a failure of chromosomes to separate correctly during the production of gametes |
| nitrogen cycle | a pathway for the movement of the element nitrogen among earth’s living organisms, waters, rocks and atmosphere |
| natural selection | survival of the fittest, a theory by Charles Darwin |
| mutation | change that affects the sequence of nitrogenous bases in DNA |
| monosaccharide | a single sugar molecule |
| molecular biology | the study of the cell’s chemical processes |
| monohybrid cross | a genetic cross in which only one trait is studied |
| multicellular | made of many cells |
| mutualism | a relationship mutually beneficial to both organisms |
| niche | the sum of all activities and interactions a species has, both with living and nonliving things that determine where it can survive and grow |
| nitrogen fixation | the process by which certain soil bacteria break down nitrogen gas and nitrogen found in dead organic matter into either nitrate or ammonia |
| nonrenewable resource | a resource that cannot be replaced, such as fossil fuels |
| nucleic acids | a large, complex molecule made of carbon, hydrogen, oxygen, nitrogen, and phosphorus |
