Cells: Is the smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane. Microscopic organisms typically consist of a single cell, which is either eukaryotic or prokaryotic.

The Diffrence between plant cells and animal cells is that 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.

The nervous system is a complex collection of nerves and specialized cells known as neurons that transmit signals between different parts of the body.]

The Bones provide a framework for the attachment of muscles and other tissues.

The Blood supplies essential nutrients to cells, such as amino acids, fatty acids, and glucose


The outermost layer of the stomach surrounding the muscularis layer is the serosa – a thin serous membrane made of simple squamous epithelial tissue and areolar connective tissue. The serosa has a smooth, slippery surface and secretes a thin, watery secretion known as serous fluid.

How the body works

Your digestive and respiratory systems, at first glance, seem very separate in their activities. In reality, however, the systems work together intimately in several ways. The results of respiratory activity allow the digestive tract to function, and vice versa. Furthermore, the systems work together to provide energy to body cells.

Paramecium: How it works Paramecium, a one-celled organism that lives in water. It is common in stagnant ponds, where it feeds on yeasts and bacteria. The paramecium is 1/250 to 3/250 inch (0.1 to 0.3 mm) long. The body is transparent and slipper-shaped, has a groove like mouth, and is covered with cilia (tiny hairs) used for swimming. The paramecium contains internal structures that function somewhat like the organs of more complex organisms. It has two nuclei instead of the single nucleus found in most cells. Two contractile vacuoles forcibly expel excess water from the cell. Reproduction is by division of the cell; occasionally, division follows an exchange of nuclear material with another paramecium. Because of its relative simplicity, the paramecium is widely studied in introductory biology courses.  #Tackk