Answer:

• An organelle is a specialized subunit within a cell that performs a specific function. Examples of organelles include the mitochondria, which generate energy for the cell, the ribosomes, which make proteins, and the endoplasmic reticulum, which helps transport proteins and lipids.

• Eukaryotic cells are cells that have a membrane-bound nucleus and other membrane-bound organelles. Prokaryotic cells, on the other hand, do not have a membrane-bound nucleus or organelles. Eukaryotic cells are typically larger and more complex than prokaryotic cells. Eukaryotic cells are found in organisms such as plants and animals, while prokaryotic cells are found in organisms such as bacteria and archaea.

• The nucleus is a membrane-bound organelle that is found in eukaryotic cells. It is the control center of the cell and contains the genetic material in the form of DNA. The nucleus is responsible for controlling the cell's growth and reproduction, as well as responding to signals from the environment. It also plays a role in controlling the cell's metabolism and in the production of proteins.