Final answer:
A cell's growth is limited because it is genetically programmed to divide a finite number of times and mutations accumulate that can inhibit division. Cell contact inhibition is a key regulatory mechanism, and plant growth is similarly regulated by environmental conditions and resource availability.
Step-by-step explanation:
Two reasons why a cell's growth is limited are as follows: First, cells are programmed to divide only a set number of times, which is part of their intrinsic cellular mechanisms like the Hayflick limit. Second, as cells grow and divide, mutations accumulate within their DNA, and cells harboring damaged DNA may cease to divide to prevent the further spread of mutations, which is also a protective measure against cancer. Moreover, normal cells exhibit contact inhibition, meaning they will stop growing once they fill their available space and come in contact with other cells, whereas cancer cells may not have this regulation and continue to divide uncontrollably.
Just as in cells, plant growth can also be limited by various factors, such as environmental conditions and resource availability. While both cells and plants need resources like nutrients for growth, there are mechanisms in place that regulate the process. These regulatory mechanisms hint at a complex interplay between genetic programming, resource availability, and environmental signaling in determining growth limitations.