Nucleus is the largest organelle in the cell and contains all the cell's genetic information in the form of DNA. The presence of a nucleus is the primary factor that distinguishes eukaryotes from prokaryotes.
A coral reef is a complex [ecosystem] of calcium carbonate shells that are home to microbes, algae, invertebrates, and fishes, and its high productivity helps provide great species richness.
Answer:
Variations are caused by mutation. random mating between organisms.
Explanation:
