A group of cells that work together to perform a common function
Alveolar walls are thin to enable the quick passage of oxygen in and out of the lungs. The lungs works hand-in-hand with the heart and also is responsible in converting blood that's de-oxygenated into an oxygenated blood that is usable by the organ systems of the body. The alveolar walls are also designed to have thin membranes so that it can expand and constrict quickly allowing us to breather properly.
Answer:
Pollination, the transfer of pollen from flower-to-flower in angiosperms or cone -to-cone in gymnosperms, takes place through self-pollination or cross-pollination. ... The placement of male and female flowers on separate plants or different parts of the plant are also barriers to self-pollination.
Explanation:
Chromatin is remodeled and nucleosomes are repositioned, thereby making specific regions of the DNA available for transcription
