Unicellular organisms are made up of only one cell that carries out all of the functions needed by the organism, while multicellular organisms use many different cells to function.
The white blood cell is called NEUTROPHIL. Neutrophils play important roles in the immune system; they move around the body via the blood stream and when they sense signals that foreign bodies are present, they move to the site of the infection and destroy them. They are among the first set of immune cells that defend the body against infection.
Fresh water is any body of water with a low salt concentration. Organisms in fresh water various challenges which includes; Osmotic concentration such that fresh water is permanently dilute and most cells cannot function at this concentration of ions. Varying temperatures, variation in oxygen levels and reproduction and life cycle due to permanence of habitat and physiological difficulty of regulating osmotic concentration in larvae and juveniles.
C. The digestive system breaks down food and the circulatory system transports the nutrients throughout the body.
The Digestive system is the system that helps the body digest food. It consists of the following organs: liver, stomach, gallbladder, large and small intestines, pancreas, rectum, and esophagus.
The Circulary system is the system that pumps blood through body. The blood contains all the nutrients and minerals the body needs. The system consists of the following organs: heart, blood vessels, blood, lymph, lymphatic vessels, and glands.