tricuspid valve is located between the right atrium and ventricle
Answer:Wildebeest are considered keystone species because their presence has myriad effects on the ecosystem, unlike those of any other species. Wildebeest are the "lawnmowers" of the Serengeti grassland. They keep grass short which in turn reduces the frequency of fires.
This has to do with SURFACE TO VOLUME RATIO. For a typical small cell, its surface area to the volume ratio get smaller as the cell grows. This implies that, if the cell grows beyond a certain limit, then the amount of nutrients that entered the cell will be limited, that is , nutrients will not be able to migrate into the cell as needed. To avoid this, the cell has to divide to reduce its surface to volume ratio.<span />
