What is a cell?                                                                                                    The smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane.

What is the difference between a plant cell and an animal cell?                   Animal cells do not have a cell wall or chloroplasts but plant cells do. Animal cells are round and irregular in shape while plant cells have fixed, rectangular shapes.

Cell wall: It acts as a gatekeeper, because it determines what can come in and out of the cell in order to keep the cell protected.

Chloroplast: Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide gas to produce food for the plant.

Centriole: The centrioles are found in pairs and move towards the poles (opposite ends) of the nucleus when it is time for cell division.

Blood has three main functions: transportation, regulation and protection. Your nervous system contains millions of nerve cells, called neurons. Neurons are highly specialised to transmit messages from one part of your body to another. There are two categories of bone cells. Osteoclasts are in the first category. They resorb (dissolve) the bone. The other category is the osteoblast family, which consists of osteoblasts that form bone, osteocytes that help maintain bone, and lining cells that cover the surface of the bone. Muscle tissue in the heart makes the heart pump blood through out the body to provide nutrients to the body. The respitory system in a human provides oxygen to the body and its organs including the heart which pumps blood through out the body. The heart pumping blood is called the circulatory system which provides blood for the digestive system system which processes nutrients consumed by the body and eliminates left over waste. Parameciums are single celled organisms that have some features that are the same as regular, multi cell organisms but they also have different parts like the cilia wjich is how the cell moves.