The main purpose is communication. like when you stub your toe , your nervous system communicates to your brain to react and have pain
Answer:the possession of feathers
Explanation:birds are warm blooded animals , that possess feathers.these feathers cover their bodies and used for flight and warmth.their forelimbs are modified into wings,which fold into a Z shape at rest.feathers grow from the skin follicles and are replaced by scales on their legs.they possess oil gland to dress the feathers.
Other features of birds include
1) beaks with no teeth
2) fully ossified bones with air cavities
3)females with left ovary and oviducts only
The operon is effectively the center of transcriptional control. In addition to its main structural genes, the operon houses an operator and a promoter. In front of the promoter lies a regulatory gene that produces repressor proteins. When a repressor is in its active state, it binds to the operator.
Hope this helped.
Check out this website http://science.jrank.org/pages/3421/Hummingbirds-Biology-hummingbirds.html
