How does nicotine and carbon monoxide and tar enter peoples lung answer?

Which property is used to identify the origin of an igneous rock? color density hardness crystal size

Gram-negative bacteria have a cell wall that is! and does not accept the stain, making itappear

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.