Answer: Nervous system.
Explanation:
Nervous system is the system found in animals that consist of all nerves and specialized cellscalled neurons and function in receiving and transmitting information to all part of the body.
Nervous system is divided into two:
Peripheral and Central nervous system.
The peripheral system consist mainly of nerves which connect Central nervous system to the other part of the body.
Nerves that transmit signals to the brain are called motor or effetent., While those that transmit signals from the body to the brain are called afferent nerves.
The Central nervous system consist of the brain and spinal cord.
The substance is a compound because it's formed by two different elements.
Answer:
They digest without the use of teeth.
Explanation:
The food trickles from the crop into the bird's stomach (proventriculus or gizzard) where digestive enzymes are added to the mix and physical grinding of the food occurs. The gizzard is why chickens do not need teeth.