They often respond to Quorum sensing which is determined by the cell density. Bacteria cells secrete molecules that can be detected by other bacteria, Quorum sensing allows bacteria to sense the concentration of these signalling molecules to monitor the local density of cells. It used by bacteria to coordinate certain behaviors , such as the production of biofilms.
Answer:
The alveolar walls and capillary walls share a membrane. That's how close they're getting. This allows oxygen and carbon dioxide to readily pass from the respiratory system to the circulation. Oxygen molecules bind to red blood cells as they return to the heart.
C, population, is not a formal taxonomic category
If the membrane of a cell were no longer selectively permeable then "<span>The cell would die as it would not be able to regulate which substances could enter and leave", since a selectively permeable membrane allows both things to enter and leave for the cell's survival. </span>
