Under normal circumstances, carbon dioxide is excreted from the the body by lungs.
Human beings have a pair of lungs that are spongy in nature and located on the sides of the chest. They are surrounded by pleura which is a layer of thin tissue. The cells in the body require oxygen. The primary function of the lungs is to transport oxygen from the air we breathe to the cells of the body and excrete carbon dioxide received in exchange for oxygen from the cells. Alveoli are present within the lung parenchyma where the exchange of gases takes place with the blood capillaries. Carbon dioxide is then exhaled from the lungs.
The lungs also serve as a means for the absorption and excretion of water and other pharmacological agents and also protect the body from unfavorable substances.
An aloe vera plant possessing a trait for extra thick leaves survives very long droughts in deserts, while and aloe vera plant that doesn't have thick leaves doesn't.
Hox genes are also called Homeotic genes. In which they act as dictators on specific areas of an organism's body on when or where it should be developed. When these genes are overactivated or inactivated it may cause genetic disorders.
