1 Transformation: bacteria simply absorb, across their cell membrane and cell wall, DNA that is floating around in the environment. 2  Conjugation: bacteria directly transfer DNA from one bacterium to another through structures called pilli. Transformation: bacteria simply absorb, across their cell membrane and cell wall, DNA that is floating around in the environment. 2  Conjugation: bacteria directly transfer DNA from one bacterium to another through structures called pilli.
Food begins its journey through the digestive system in the mouth, before being pushed by a series of involuntary muscle contractions through the esophagus, then the stomach, and then the small and large intestines.
The esophagus is a long, muscular tube that connects an animalâs stomach to its mouth. Distinct from the windpipe, which transports air into and out of the lungs, the esophagus usually carries food and water from the mouth to the stomach. However, during vomiting, the esophagus carries stomach acids and undigested food from the stomach back out through the mouth.