If one population dies out, all the populations that depend on that species for food may also die out. A change in one population affects the entire community because all the populations of a community depend on each other. A population is all the members of one type of organism living in an ecosystem.
I may be wrong but I think the answer is Photosynthesis.
For this question I'm not too sure what you're asking because cells that transport water are basically xylem cells and these cells are hollow with nothing in them, and they transport water against gravity because of transpiration pull, capillary action and root pressure.
The cells that I know of with many mitochondria for transport would be the phloem so that the mitochondria can carry out cellular respiration to release energy for the translocation of sucrose.
Jeffery Arnett is a physiologist who coined the term "emerging adulthood." This has previously been known as; delayed adulthood, transition age youth, youthhood, and the twixter years. He believes that the period between adolescence and adulthood is when the person reaches adulthood but doesn't have children, have sufficient funds, or have their own home. He believes it starts at 18 and ends around 25 years of age. He thinks this is when people are still looking for love, make money to spend on recreational activities, and trying to develop their own identities. This theory is highly controversial and has been contested by developmental psychologists.