What is cell, cell membrane, nucleus …

Cell: The basic structural unit of a living organism is called cell. All living beings are made up of cells. Some organisms are made up of a single cell or of a few numbers of cells. Some other organisms are made up of numerous cells.
Cell Membrane: Cell membrane is also called plasma membrane. It makes the boundary of a cell. It is composed of protein and lipid. It is porous and allows various materials to pass through it.
Cytoplasm: A jelly-like substance is present between the cell and nucleus. It is called cytoplasm. Different cell organelles are present in the cytoplasm. Examples of cell organelles are; mitochondria, Golgi body, ribosomes, lysosomes, chloroplast, etc.
Nucleus: This is a spherical structure which is present inside the cell; usually at the centre of the cell. Nucleus is surrounded by a double membrane called nuclear membrane. A dot-like structure; called nucleolus is present inside the nucleus. Nucleus contains chromosomes which are thread-like structures. Genes are present on chromosome. They are responsible for transferring characters from parents to their offspring.