The cell membrane is semi permeable in nature, that is, it allows the passage of some substances while it disallows some substances. Small and non polar molecules pass quite easily through the cell membrane but large and polar molecules can not do this.
The substances which can easily pass through the cell membranes make use of passive transports such as diffusion and facilitated diffusion to enter the cells while substances which can not pass through the cell membranes on their own make use of active transport. Examples of active transport are endocytosis and ectocytosis,
These alveoli are the smallest types of lung tissue, and one of the most important. In addition to being the primary means by which oxygen enters and carbon dioxide escapes the bloodstream, these small pouches of air are also the reason why the lungs do not totally collapse when a person breathes out. This is because they contain a cell that secretes a special chemical to lower the surface temperature to prevent lung collapse. The alveoli also contain other cells that secrete chemicals to attack and remove any foreign objects in the lungs, such as dust, dirt and other debris.
In addition to making up alveolar sacs, alveoli also form alveolar ducts. It is estimated that there are more than 300 million alveoli in the human lungs, all of which are located in either alveolar ducts or sacs that are found at the end of the smaller passageways, or bronchioles, in the lungs.
SHORT ANSWER:
Alveolar sacs contain tiny pouches called alveoli, whose primary function is gas diffusion. These clusters of alveoli have thin walls that allow oxygen to pass easily from the lungs into the bloodstream and carbon dioxide to flow from the blood to the lungs so it can exit the body.
Answer:
ur answer is A
Explanation:
just took the test good luck :)
I think it’s A, begins to change :))
Answer:
B.
Explanation:
They take up the host organelles to reproduce more viruses inside.
