Ans.
Unicellular organisms are those organisms that are made up of a single cell, while multicellular organisms are made of up more than one cell. During 17th century, a scientist could distinguish between an unicellular and a multicellular organism by using simple microscope, developed by Antony Van Leeuwenhoek. In the mid-20th century and 21st Century, a scientist could make distinction between unicellular and multicellular organisms, by using advance microscopy techniques, such as electron microscopy and electron microscopy.
Answer:
The movement pushes food and liquid through your GI tract and mixes the contents within each organ. The muscle behind the food contracts and squeezes the food forward, while the muscle in front of the food relaxes to allow the food to move. The digestive process starts when you put food in your mouth.