Which describes gas exchange in the respiratory system?
gas exchange happens through diffusion.
gas exchange removes oxygen from the body.
gas exchange occurs between the body’s cells and bronchi.
gas exchange protects the body against foreign invaders.

Pls me i need this ! each cell has genes activated depending on it's job and what kind of cell it is. it is the presence of that causes the repressor protein to fall off and unblock the gene on the lac operon. if a gene is turned on then it is being an additional circular chromosome found in some bacteria that is used in genetic engineering.