Regulation of the expression of genes refers to different processes tge cells use to increase or decrease the production of some gene content. It involve Turing gene on and off so as to ensure that appropriate genes are expressed at the right times. This allow organism to respond to changes in their environment.
Gas exchange occurs at the alveoli in the lungs and takes place by diffusion. The alveoli are surrounded by capillaries so oxygen and carbon dioxide diffuse between the air in the alveoli and the blood in the capillaries.
